1540 lines
53 KiB
Plaintext
1540 lines
53 KiB
Plaintext
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I T T Y B I T T Y C O M P U T E R S
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TINY BASIC User Manual
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Congratulations! You have received the first of what we hope
|
||
is a long line of low cost software for hobby computers. We are
|
||
operating on a low margin basis, and hope to make a profit on
|
||
volume. Please help us to stay in business by respecting the
|
||
Copyright notices on the software and documentation.
|
||
If you are in a hurry to try TINY BASIC, Appendix C will tell
|
||
you how to get on the air. Then come back and read the rest of this
|
||
manual --- most of it is useful information.
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The TINY BASIC interpreter program has been extensively tested
|
||
for errors ("bugs"), but it would be foolish to claim of any program
|
||
that it is guaranteed bug-free. This program does come with a
|
||
"Limited Warranty" in that any errors discovered will be corrected in
|
||
the first 90 days. Catastrophic bugs will be corrected by
|
||
automatically mailing out corrected versions to all direct mail
|
||
customers and local dealers. Minor bugs will be corrected by
|
||
request. In any case this warranty is limited to replacement of the
|
||
Program Tape and/or documentation, and no liability for consequential
|
||
damages is implied.
|
||
If you think you have found a bug, make a listing of the
|
||
program that demonstrates the bug, together with the run input and
|
||
output. Indicate on the listing what you think is wrong and what
|
||
version number you are running and your serial number (on the tape
|
||
leader). Mail this to:
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ITTY BITTY COMPUTERS
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P.0. Box 6539
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San Jose, CA 95150
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We will try to be responsive to your needs.
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||
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----------
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(C) Copyright 1976 by Tom Pittman. All rights reserved.
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"Itty Bitty" is a Trademark of the ITTY BITTY COMPUTERS Company.
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1
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||
TINY BASIC was conceived by the dragons at the People's
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||
Computer Company (PCC), a non-profit corporation in Menlo Park CA.
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and its implementation defined by Dennis Allison and others in the
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PCC newspaper and an offshoot newsletter. The implementation of this
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||
program follows the philosophy defined there. The reader is referred
|
||
to PCC v.4 Nos 1-3 for a discussion of the inner workings of this
|
||
software.
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||
In keeping with the "small is good" philosophy, TINY BASIC
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||
employs the two level interpreter approach (with its consequent speed
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cost) so that the whole system occupies only 2K of program memory
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(exclusive of user program; some versions are slightly larger).
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||
With 1K of additional RAM small but useful user programs (50 lines or
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||
less) may be accommodated. A system with 4K of RAM can contain the
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||
interpreter and about 100 lines of user program.
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TINY BASIC is offered in several versions for each processor.
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One is designed to be used with an arbitrary operating system, and
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executes out of low memory (e.g. 0100-08FF for the 6800). The other
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||
versions are configured for unusual memory requirements of particular
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||
operating systems. All are "clean" programs, in that they will
|
||
execute properly from protected memory (such as PROM). Direct
|
||
addressing is used for interpreter variables as much as possible, so
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||
memory Page 00 is largely dedicated. In all cases the user programs
|
||
are placed at the end of that part of lower memory used by TINY, and
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||
they may occupy all the remaining contiguous memory. Appendix D is a
|
||
a summary of the important low-memory addresses.
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||
TINY BASIC is designed to be I/O independent, with all input
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and output funneled through three jumps placed near the beginning of
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||
the program. In the non-standard versions these are preset for the
|
||
particular operating system I/O, so the discussion to follow is
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||
primarily concerned with the standard versions. For this
|
||
discussion, it is assumed that the interpreter begins at hex address
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0100, though the remarks may be applied to other versions with an
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appropriate offset.
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||
Location 0106 is a JMP to a subroutine to read one ASCII
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character from the console/terminal. Location 0109 is a JMP to a
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||
subroutine to type or display one ASCII character on the
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console/terminal. In both cases the character is in the A
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accumulator, but the subroutine need not preserve the contents of the
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other registers. It is assumed that the character input routine will
|
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simultaneously display each character as it is input; if this is not
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||
the case, the JMP instruction in location 0106 may be converted to a
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JSR, so that each character input flows through the output subroutine
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(which in this case must preserve A) before being fed to TINY.
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Users with terminals using Baudot or some other non-ASCII code should
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||
perform the character conversion in the Input and Output subroutines.
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||
If your console is a CRT and/or you have no need to output or
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||
display extra pad characters with each Carriage Return and Linefeed,
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||
you may intercept these in the output routine to bypass their
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display. Each input prompt by TINY is followed by an "X-ON"
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character (ASCII DC1) with the sign bit set to 1 (all other
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characters except rubout are output with the sign bit set to 0) so
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these are also readily detected and deleted from the output stream.
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Appendix C shows how to perform these tests.
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A third subroutine provided by you is optional, and gives TINY
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2
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a means to test for the BREAK condition in your system. Appendix C
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||
shows how this subroutine may be implemented for different types of
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||
I/O devices. If you choose to omit this subroutine, TINY will assume
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that a BREAK condition never happens; to include it, simply replace
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locations 010C-010E with a JMP to your subroutine, which returns with
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the break condition recorded in the Carry flag (1 = BREAK, 0 = no
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||
BREAK). The Break condition is used to interrupt program execution,
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||
or to prematurely terminate a LIST operation. Tiny responds to the
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||
Break condition any time in the LIST, or just before examining the
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next statement in program execution. If a LIST statement included
|
||
within a program is aborted by the Break condition, the Break
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||
condition must be held over to the next statement fetch (or repeated)
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||
to stop program execution also.
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||
All input to Tiny is buffered in a 72 character line,
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||
terminated by a Carriage Return ("CR"). Excess characters are
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||
ignored, as signaled by ringing the console/terminal bell. When the
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CR is typed in, Tiny will echo it with a Linefeed, then proceed to
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process the information in the line. If a typing error occurs during
|
||
the input of either a program line or data for an INPUT statement,
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||
the erroneous characters may be deleted by "backspacing" over them
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||
and retyping. If the entire line is in error, it may be canceled
|
||
(and thus ignored) by typing the "Cancel" key. The Backspace code is
|
||
located near the beginning of the program (location 010F), and is
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set by default to "left-arrow" or ASCII Underline (shift-O on your
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Teletype). To change this to the ASCII Standard Backspace code (or
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anything else you choose), the contents of location 010F may be
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changed to the desired code. Similarly the Cancel code is located at
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memory address 0110, and is set by default to the ASCII Cancel code
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(Control-X). Four characters which may not be used for line edits
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||
(Backspace or Cancel) are DC3 (hex 13), LF (0A), NUL (00), and DEL
|
||
(FF). These codes are trapped by the TINY BASIC input routines
|
||
before line edits are tested.
|
||
When Tiny ends a line (either input or output), it types a CR,
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||
two pad characters, a Linefeed, and one more pad character. The pad
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||
character used is defined by the sign bit in location 0111, and is
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||
set by default to the "Rubout" or Delete code (hex FF; Location 0111
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||
Bit 7 = 1) to minimize synchronization loss for bit-banger I/O
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||
routines. The pad character may be changed to a Null (hex 00) by
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||
setting the sign of location 0111 to 0. The remainder of this byte
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||
defines the number of Pad characters between the CR and linefeed.
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||
More than two pad characters may be required if large user programs
|
||
are to be loaded from tape (see comments on Tape Mode, below).
|
||
TINY BASIC has a provision for suppressing output (in
|
||
particular line prompts) when using paper tape for loading a program
|
||
or inputting data. This is activated by the occurrence of a Linefeed
|
||
in the input stream (note that the user normally has no cause to type
|
||
a Linefeed since it is echoed in response to each CR), and disables
|
||
all output (including program output) until the tape mode is
|
||
deactivated. This is especially useful in half-duplex I/O systems
|
||
such as that supported by Mikbug, since any output would interfere
|
||
with incoming tape data. The tape mode is turned off by the
|
||
occurrence of an X-OFF character (ASCII DC3, or Control-S) in the
|
||
input, by the termination of an executing program due to an error, or
|
||
after the execution of any statement or command which leaves Tiny in
|
||
the command mode. The tape mode may be disabled completely by
|
||
replacing the contents of memory location 0112 with a 00.
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||
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||
3
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||
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||
Memory location 0113 is of interest to those 6800 users with
|
||
extensive operating systems. Normally Tiny reserves 32 bytes of
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||
stack space for use by the interpreter and I/O routines (including
|
||
interrupts). Up to half of these may be used by Tiny in normal
|
||
operation, leaving not more than 16 bytes on the stack for I/O. If
|
||
your system allows nested interrupts or uses much more than ten or
|
||
twelve stack bytes for any purpose, additional space must be
|
||
allocated on the stack. Location 0113 contains the reserve stack
|
||
space parameter used by Tiny, and is normally set to 32 (hex 20). If
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||
your system requires more reserve, this value should be augmented
|
||
accordingly before attempting to run the interpreter.
|
||
All of these memory locations are summarized in Appendix D.
|
||
Note that there are no Input or Output instructions or interrupt
|
||
disables in the interpreter itself; aside from the routines provided
|
||
for your convenience (which you may connect or disconnect), your
|
||
system has complete control over the I/O and interrupt structure of
|
||
the TINY BASIC environment.
|
||
|
||
TINY BASIC is designed to use all of the memory available to it
|
||
for user programs. This is done by scanning all the memory from the
|
||
beginning of the user program space (e.g. 0900 for the standard 6800
|
||
version) for the end of contiguous memory. This then becomes the
|
||
user program space, and any previous contents may be obliterated.
|
||
If it is desired to preserve some part of this memory for machine
|
||
language subroutines or I/O routines, it will be necessary to omit
|
||
the memory scan initialization. This is facilitated in TINY BASIC by
|
||
the definition of two starting addresses. Location 0100 (or the
|
||
beginning of the interpreter) is the "Cold Start" entry point, and
|
||
makes no assumptions about the contents of memory, except that it is
|
||
available. Location 0103 is the "Warm Start" entry point, and
|
||
assumes that the upper and lower bounds of the user program memory
|
||
have been defined, and that the program space is correctly
|
||
formatted. The Warm Start does not destroy any TINY BASIC programs
|
||
in the program space, so it may be used to recover from catastrophic
|
||
failures. The lower bound is stored in locations 0020-0021 and the
|
||
upper bound is in locations 0022-0023. When using the Warm Start to
|
||
preserve memory, you should be sure these locations contain the
|
||
bounds of the user space. Also when using the Warm Start instead of
|
||
the Cold Start, the first command typed into TINY should be "CLEAR"
|
||
to properly format the program space.
|
||
|
||
|
||
STATEMENTS
|
||
|
||
TINY BASIC is a subset of Dartmouth BASIC, with a few
|
||
extensions to adapt it to the microcomputer environment. Appendix B
|
||
contains a BNF definition of the language; the discussion here is
|
||
intended to enable you to use it. When TINY issues a line prompt (a
|
||
colon on the left margin) you may type in a statement with or without
|
||
a line number. If the line number is included, the entire line is
|
||
inserted into the user program space in line number sequence, without
|
||
further analysis. Any previously existing line with the same line
|
||
number is deleted or replaced by the new line. If the new line
|
||
consists of a line number only, it is considered a deletion, and
|
||
nothing is inserted. Blanks are not significant to TINY, so blanks
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||
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||
|
||
4
|
||
|
||
imbedded in the line number are ignored; however, after the first
|
||
non-blank, non-numeric character in the line, all blanks are
|
||
preserved in memory.
|
||
The following are valid lines with line numbers!
|
||
|
||
123 PRINT "HELLO"
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||
456 G O T O 1 2 3
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||
7 8 9 PRINT "THIS IS LINE # 789"
|
||
123
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||
32767 PRINT "THIS IS THE LARGEST LINE #"
|
||
1PRINT"THIS, IS THE SMALLEST LINE #"
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||
10000 TINY BASIC DOES NOT CHECK
|
||
10001 FOR EXECUTABLE STATEMENTS ON INSERTION.
|
||
|
||
0 Is not a valid line number.
|
||
|
||
If the input line does not begin with a line number it is
|
||
executed directly, and must consist of one of the following statement
|
||
types:
|
||
|
||
LET GOTO REM
|
||
IF...THEN GOSUB CLEAR
|
||
INPUT RETURN LIST
|
||
PRINT END RUN
|
||
|
||
These statement types are discussed in more detail in the pages
|
||
to follow.
|
||
Note that all twelve statement types may be used in either the
|
||
Direct Execution mode (without a line number) or in a program
|
||
sequence (with a line number). Two of the statements (INPUT and RUN)
|
||
behave slightly differently in these two operating modes, but
|
||
otherwise each statement works the same in Direct Execution as within
|
||
a program. Obviously there is not much point in including such
|
||
statements as RUN or CLEAR in a program, but they are valid.
|
||
Similarly, a GOSUB statement executed directly, though valid, is
|
||
likely to result in an error stop when the corresponding RETURN
|
||
statement is executed.
|
||
|
||
|
||
EXPRESSIONS
|
||
|
||
Many of these statement types involve the use of EXPRESSIONS.
|
||
An Expression is the combination of one or more NUMBERS or VARIABLES,
|
||
joined by OPERATORS, and possibly grouped by Parentheses. There are
|
||
four Operators:
|
||
+ addition
|
||
- subtraction
|
||
* multiplication
|
||
/ division
|
||
These are hierarchical, so that in an expression without parentheses,
|
||
multiplication and division are performed before addition and
|
||
subtraction. Similarly, sub-expressions within parentheses are
|
||
evaluated first. Otherwise evaluation proceeds from left to right.
|
||
Unary operators (+ and -) are allowed in front of an expression to
|
||
denote its sign.
|
||
|
||
|
||
5
|
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|
||
A Number is any sequence of decimal digits (0, 1, 2, ... 9),
|
||
denoting the decimal number so represented. Blanks have no
|
||
significance and may be imbedded within the number for readability if
|
||
desired, but commas are not allowed. All numbers are evaluated as
|
||
16-bit signed numbers, so numbers with five or more digits are
|
||
truncated modulo 65536, with values greater than 32767 being
|
||
considered negative. The following are some valid numbers (note
|
||
that the last two are equivalent to the first two in TINY):
|
||
|
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0
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100
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||
10 000
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||
1 2 3 4
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32767
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65536
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||
65 636
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||
|
||
A Variable is any Capital letter (A, B, ... Z). This variable
|
||
is assigned a fixed location in memory (two bytes, the address of
|
||
which is twice the ASCII representation of the variable name). It
|
||
may assume any value in the range, -32768 to +32767, as assigned to
|
||
it by a LET or INPUT statement.
|
||
The following are some examples of valid expressions:
|
||
A
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123
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1+2-3
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B-14*C
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||
(A+B)/(C+D)
|
||
-128/(-32768+(I*1))
|
||
(((((Q)))))
|
||
|
||
All expressions are evaluated as integers modulo 65536. Thus
|
||
an expression such as
|
||
N / P * P
|
||
may not evaluate to the same value as (N), and in fact this may be
|
||
put to use to determine if a variable is an exact multiple of some
|
||
number. TINY BASIC also makes no attempt to discover arithmetic
|
||
overflow conditions, except in the case of an attempt to divide by
|
||
zero (which results in an error stop). Thus all of the following
|
||
expressions evaluate to the same value:
|
||
-4096
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||
15*4096
|
||
32768/8
|
||
30720+30720
|
||
|
||
TINY BASIC allows two intrinsic functions. These are:
|
||
RND (range)
|
||
USR (address,Xreg,Areg)
|
||
Either of these functions may be used anywhere an (expression) is
|
||
appropriate.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
6
|
||
|
||
FUNCTIONS
|
||
|
||
|
||
RND (range)
|
||
|
||
This function has as its value, a positive pseudo-random number
|
||
between zero and range-1, inclusive. If the range argument is zero
|
||
an error stop results.
|
||
|
||
|
||
|
||
USR (address)
|
||
USR (address,Xreg)
|
||
USR (address,Xreg,Areg)
|
||
|
||
This function is actually a machine-language subroutine call to
|
||
the address in the first argument. If the second argument is
|
||
included the index registers contain that value on entry to the
|
||
subroutine, with the most significant part in X. If the third
|
||
argument is included, the accumulators contain that value on entry to
|
||
the subroutine, with the least significant part in A. On exit, the
|
||
value in the Accumulators (for the 6800; A and Y for the 6502)
|
||
becomes the value of the function, with the least significant part in
|
||
A. All three arguments are evaluated as normal expressions.
|
||
It should be noted that machine language subroutine addresses
|
||
are 16-bit Binary numbers. TINY BASIC evaluates all expressions to
|
||
16-bit binary numbers, so any valid expression may be used to define
|
||
a subroutine address. However, most addresses are expressed in
|
||
hexadecimal whereas TINY BASIC only accepts numerical constants in
|
||
decimal. Thus to jump to a subroutine at hex address 40AF, you must
|
||
code USR(16559). Hex address FFB5 is similarly 65461 in decimal,
|
||
though the equivalent (-75) may be easier to use.
|
||
For your convenience two subroutines have been included in the
|
||
TINY BASIC interpreter to access memory. If S contains the address
|
||
of the beginning of the TINY BASIC interpreter (256 for standard
|
||
6800, 512 for standard 6502, etc.), then location S+20 (hex 0114) is
|
||
the entry point of a subroutine to read one byte from the memory
|
||
address in the index register, and location S+24 (hex 0118) is the
|
||
entry point of a subroutine to store one byte into memory.
|
||
Appendix E gives examples of the USR function.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
7
|
||
|
||
STATEMENT TYPES
|
||
|
||
|
||
PRINT print-list
|
||
PR print-list
|
||
|
||
This statement prints on the console/terminal the values of the
|
||
expressions and/or the contents of the strings in the print-list.
|
||
The print-list has the general form,
|
||
item,item... or item;item...
|
||
The items may be expressions or alphanumeric strings enclosed in
|
||
quotation marks (e.g. "STRING"). Expressions are evaluated and
|
||
printed as signed numbers; strings are printed as they occur in the
|
||
PRINT statement. When the items are separated by commas the printed
|
||
values are justified in columns of 8 characters wide; when semicolons
|
||
are used there is no separation between the printed items. Thus,
|
||
PRINT 1,2,3
|
||
prints as
|
||
1 2 3
|
||
and
|
||
PRINT 1;2;3
|
||
prints as
|
||
123
|
||
Commas and semicolons, strings and expressions may be mixed in one
|
||
PRINT statement at will.
|
||
If a PRINT statement ends with a comma or semicolon TINY BASIC
|
||
will not terminate the output line so that several PRINT statements
|
||
may print on the same output line, or an output message may be
|
||
printed on the same line as an input request (see INPUT). When the
|
||
PRINT statement does not end with a comma or semicolon the output is
|
||
terminated with a carriage return and linefeed (with their associated
|
||
pad characters). To aid in preparing data tapes for input to other
|
||
programs, a colon at the end of a print-list will output an "X-OFF"
|
||
control character just before the Carriage Return.
|
||
|
||
Although the PRINT statement generates the output immediately
|
||
while scanning the statement line, output lines are limited to 125
|
||
characters, with excess suppressed.
|
||
|
||
While the Break key will not interrupt a PRINT statement in
|
||
progress, the Break condition will take effect at the end of the
|
||
current PRINT statement.
|
||
|
||
The following are some examples of valid PRINT statements:
|
||
PRINT "A=";A,"B+C=";B+C
|
||
PR (one blank line)
|
||
PRI (prints the value of I)
|
||
PRINT 1,","Q*P;",",R/42:
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
8
|
||
|
||
INPUT input-list
|
||
|
||
This statement checks to see if the current input line is
|
||
exhausted. If it is, a question mark is prompted with an X-ON
|
||
control character, and a new line is read in. Then or otherwise, the
|
||
input line is scanned for an expression which is evaluated. The
|
||
value thus derived is stored in the first variable in the input-list.
|
||
If there are more variables in the input-list the process is
|
||
repeated. In an executing program, several values may be input on a
|
||
single request by separating them with commas. If these values are
|
||
not used up in the current INPUT statement they are saved for
|
||
subsequent INPUT statements. The question mark is prompted only when
|
||
a new line of input values is required. Note that each line of input
|
||
values must be terminated by a carriage return. Since expressions
|
||
may be used as input values, any letter in the input line will be
|
||
interpreted as the value of that variable. Thus if a program sets
|
||
the value of A to 1, B to 2, and C to 3, and the following statement
|
||
occurs during execution:
|
||
INPUT X,Y,Z
|
||
and the user types in
|
||
A,C,B
|
||
the values entered into X, Y, and Z will be 1, 3, and 2,
|
||
respectively, just as if the numbers had been typed in. Note also
|
||
that blanks on the input line are ignored by TINY, and the commas are
|
||
required only for separation in cases of ambiguity. In the example
|
||
above
|
||
ACB
|
||
could have been typed in with the same results. However an input,
|
||
line typed in as
|
||
+1 -3 +6 0
|
||
will be interpreted by TINY as a single value (=58) without commas
|
||
for separators. There is one anomaly in the expression input
|
||
capability: if in response to this INPUT, the user types,
|
||
RND+3
|
||
TINY will stop on a bad function syntax error (the RND function must
|
||
be of the form, RND(x)); but if the user types,
|
||
RN,D+3
|
||
the values in the variables R, N, and the expression (D+3) will be
|
||
input. This is because in the expression evaluator the intrinsic
|
||
function names are recognized before variables, as long as they are
|
||
correctly spelled.
|
||
|
||
Due to the way TINY BASIC buffers its input lines, the INPUT
|
||
statement cannot be directly executed for more than one variable at a
|
||
time, and if the following statement is typed in without a line
|
||
number,
|
||
INPUT A,B,C
|
||
the value of B will be copied to A, and only one value (for C) will
|
||
be requested from the console/terminal. Similarly, the statement,
|
||
INPUT X,1,Y,2,Z,3
|
||
will execute directly (loading X, Y, and Z with the values 1, 2, and
|
||
3), requesting no input, but with a line number in a program this
|
||
statement will produce an error stop after requesting one value.
|
||
|
||
If the number of expressions in the input line does not match
|
||
the number of variables in the INPUT statement, the excess input is
|
||
|
||
9
|
||
|
||
saved for the next INPUT statement, or another prompt is issued for
|
||
more data. The user should note that misalignment in these
|
||
circumstances may result in incorrect program execution (the wrong
|
||
data to the wrong variables). If this is suspected, data entry may be
|
||
typed in one value at a time to observe its synchronization with
|
||
PRINT statements in the program.
|
||
There is no defined escape from an input request, but if an
|
||
invalid expression is typed (such as a period or a pair of commas) an
|
||
invalid expression error stop will occur.
|
||
|
||
Because Tiny Basic does not allow arrays, about the only way to
|
||
process large volumes of data is through paper tape files. Each
|
||
input request prompt consists of a question mark followed by an X-ON
|
||
(ASCII DC1) control character to turn on an automatic paper tape
|
||
reader on the Teletype (if it is ready). A paper tape may be
|
||
prepared in advance with data separated by commas, and an X-OFF
|
||
(ASCII DC3 or Control-S) control character preceding the CR (a
|
||
Teletype will generally read at least one more character after the
|
||
X-OFF). In this way the tape will feed one line at a time, as
|
||
requested by the succession of INPUT statements. This tape may also
|
||
be prepared from a previous program output (see the PRINT
|
||
statement).
|
||
|
||
|
||
|
||
|
||
|
||
LET var = expression
|
||
var = expression
|
||
|
||
This statement assigns the value of the expression to the
|
||
variable (var). The long form of this statement (i.e. with the
|
||
keyword LET) executes slightly faster than the short form. The
|
||
following are valid LET statements:
|
||
|
||
LET A = B+C
|
||
I = 0
|
||
LET Q = RND (RND(33)+5)
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
10
|
||
|
||
GOTO expression
|
||
|
||
The GOTO statement permits changes in the sequence of program
|
||
execution. Normally programs are executed in the numerical sequence
|
||
of the program line numbers, but the next statement to be executed
|
||
after a GOTO has the line number derived by the evaluation of the
|
||
expression in the GOTO statement. Note that this permits you to
|
||
compute the line number of the next statement on the basis of program
|
||
parameters during program execution. An error stop occurs if the
|
||
evaluation of the expression results in a number for which there is
|
||
no line. If a GOTO statement is executed directly, it has the same
|
||
effect as if it were the first line of a program, and the RUN
|
||
statement were typed in, that is, program execution begins from that
|
||
line number, even though it may not be the first in the program.
|
||
Thus a program may be continued where it left off after correcting
|
||
the cause of an error stop. The following are valid GOTO
|
||
statements:
|
||
GOTO 100
|
||
GO TO 200+I*10
|
||
G 0 T 0 X
|
||
|
||
|
||
|
||
|
||
|
||
|
||
GOSUB expression
|
||
|
||
The GOSUB statement is like the GOTO statement, except that TINY
|
||
remembers the line number of the GOSUB statement, so that the next
|
||
occurrence of a RETURN statement will result in execution proceeding
|
||
from the statement following the GOSUB. Subroutines called by GOSUB
|
||
statements may be nested to any depth, limited only by the amount of
|
||
user program memory remaining. Note that a GOSUB directly executed
|
||
may result in an error stop at the corresponding RETURN. The
|
||
following are some examples of valid GOSUB statements:
|
||
GOSUB 100
|
||
GO SUB 200+I*10
|
||
|
||
|
||
|
||
|
||
|
||
|
||
RETURN
|
||
|
||
The RETURN statement transfers execution control to the line
|
||
following the most recent unRETURNed GOSUB. If there is no matching
|
||
GOSUB an error stop occurs.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
11
|
||
|
||
IF expression rel expression THEN statement
|
||
IF expression rel expression statement
|
||
|
||
The IF statement compares two expressions according to one of
|
||
six relational operators. If the relationship is True, the statement
|
||
is executed; if False, the associated statement is skipped. The six
|
||
relational operators are:
|
||
= equality
|
||
< less than
|
||
> greater than
|
||
<= less or equal (not greater)
|
||
>= greater or equal (not less)
|
||
<>, >< not equal (greater or less)
|
||
|
||
The statement may be any valid TINY BASIC statement (including
|
||
another IF statement). The following are valid IF statements:
|
||
IF I>25 THEN PRINT "ERROR"
|
||
IF N/P*P=N GOTO 100
|
||
IF 1=2 Then this is nonsense
|
||
IF RND (100) > 50 THEN IF I <> J INPUT Q,R
|
||
|
||
|
||
|
||
|
||
|
||
|
||
END
|
||
|
||
The END statement must be the last executable statement in a
|
||
program. Failure to include an END statement will result in an error
|
||
stop after the last line of the program is executed. The END
|
||
statement may be used to terminate a program at any time, and there
|
||
may be as many END statements in a program as needed. The END
|
||
statement also clears out any saved GOSUB line numbers remaining, and
|
||
may be used for that purpose in the direct execution mode.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
REM comments
|
||
|
||
The REM statement permits comments to be interspersed in the
|
||
program. Its execution has no effect on program operation, except
|
||
for the time taken.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
12
|
||
|
||
CLEAR
|
||
|
||
The CLEAR statement formats the user program space, deleting
|
||
any previous programs. If included in a program (i.e. with a line
|
||
number) the program becomes suicidal when the statement is executed,
|
||
although no error results. If the Warm Start is used to initialize
|
||
the interpreter, this must be the first command given.
|
||
|
||
|
||
|
||
RUN
|
||
RUN,expression-list
|
||
|
||
The RUN statement is used to begin program execution at the
|
||
first (lowest) line number. If the RUN statement is directly
|
||
executed, it may be followed by a comma, followed by values to be
|
||
input when the program executes an INPUT statement.
|
||
If the RUN statement is included in a program with a line
|
||
number, its execution works like a GO TO first statement of the
|
||
program.
|
||
|
||
|
||
|
||
LIST
|
||
LIST expression
|
||
LIST expression,expression
|
||
|
||
The LIST statement causes part or all of the user program to be
|
||
listed. If no parameters are given, the whole program is listed. A
|
||
single expression parameter in evaluated to a line number which, if
|
||
it exists, is listed. If both expression parameters are given, all
|
||
of the lines with line numbers between the two values (inclusive) are
|
||
listed. If the last expression in the LIST statement evaluates to a
|
||
number for which there is no line, the next line above that number
|
||
which does exist (if any) is listed as the last line. Zero is not a
|
||
valid line number, and an error stop will occur if one of the
|
||
expressions evaluates to zero. A LIST statement may be included as
|
||
part of the program, which may be used for printing large text
|
||
strings such as instructions to the operator. A listing may be
|
||
terminated by the Break key.
|
||
If the terminal punch (or cassette recorder) is turned on for a
|
||
LIST operation, the tape may be saved to reload the program into TINY
|
||
at a later time.
|
||
The following are valid LIST statements:
|
||
LIST
|
||
LIST 75+25 (lists line 100)
|
||
LIST 100,200
|
||
LIST 500,400 (lists nothing)
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
13
|
||
|
||
A P P E N D I X A
|
||
|
||
ERROR MESSAGE SUMMARY
|
||
|
||
|
||
0 Break during execution
|
||
8 Memory overflow; line not inserted
|
||
9 Line number 0 not allowed
|
||
13 RUN with no program in memory
|
||
18 LET is missing a variable name
|
||
20 LET is missing an =
|
||
23 Improper syntax in LET
|
||
25 LET is not followed by END
|
||
34 Improper syntax in GOTO
|
||
37 No line to GO TO
|
||
39 Misspelled GOTO
|
||
40,41 Misspelled GOSUB
|
||
46 GOSUB subroutine does not exist
|
||
59 PRINT not followed by END
|
||
62 Missing close quote in PRINT string
|
||
73 Colon in PRINT is not at end of statement
|
||
75 PRINT not followed by END
|
||
95 IF not followed by END
|
||
104 INPUT syntax bad - expects variable name
|
||
123 INPUT syntax bad - expects comma
|
||
124 INPUT not followed by END
|
||
132 RETURN syntax bad
|
||
133 RETURN has no matching GOSUB
|
||
134 GOSUB not followed by END
|
||
139 END syntax bad
|
||
154 Can't LIST line number 0
|
||
164 LIST syntax error - expects comma
|
||
183 REM not followed by END
|
||
184 Missing statement type keyword
|
||
186 Misspelled statement type keyword
|
||
188 Memory overflow: too many GOSUB's ...
|
||
211 ... or expression too complex
|
||
224 Divide by 0
|
||
226 Memory overflow
|
||
232 Expression too complex ...
|
||
233 ... using RND ...
|
||
234 ... in direct evaluation;
|
||
253 ... simplify the expression
|
||
259 RND (0) not allowed
|
||
266 Expression too complex ...
|
||
267 ... for RND
|
||
275 USR expects "(" before arguments
|
||
284 USR expects ")" after arguments
|
||
287 Expression too complex ...
|
||
288 ... for USR
|
||
290 Expression too complex
|
||
293 Syntax error in expression - expects value
|
||
296 Syntax error - expects ")"
|
||
298 Memory overflow (in USR)
|
||
303 Expression too complex (in USR)
|
||
|
||
|
||
14
|
||
|
||
304 Memory overflow (in function evaluation)
|
||
306 Syntax error - expects "(" for function arguments
|
||
330 IF syntax error - expects relation operator
|
||
|
||
Other error message numbers may possibly occur if the
|
||
interpreter is malfunctioning. If this happens, check the program in
|
||
memory, or reload it, and try again.
|
||
|
||
Error number 184 may also occur if TINY BASIC is incorrectly
|
||
interfaced to the keyboard input routines. A memory dump of the
|
||
input line buffer may disclose this kind of irregularity.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
15
|
||
|
||
A P P E N D I X B
|
||
|
||
FORMAL DEFINITION OF TINY BASIC
|
||
|
||
|
||
line ::= number statement CR
|
||
statement CR
|
||
statement ::= PRINT printlist
|
||
PR printlist
|
||
INPUT varlist
|
||
LET var = expression
|
||
var = expression
|
||
GOTO expression
|
||
GOSUB expression
|
||
RETURN
|
||
IF expression relop expression THEN statement
|
||
IF expression relop expression statement
|
||
REM commentstring
|
||
CLEAR
|
||
RUN
|
||
RUN exprlist
|
||
LIST
|
||
LIST exprlist
|
||
printlist ::=
|
||
printitem
|
||
printitem :
|
||
printitem separator printlist
|
||
printitem ::= expression
|
||
"characterstring"
|
||
varlist ::= var
|
||
var , varlist
|
||
exprlist ::= expression
|
||
expression , exprlist
|
||
expression ::= unsignedexpr
|
||
+ unsignedexpr
|
||
- unsignedexpr
|
||
unsignedexpr ::= term
|
||
term + unsignedexpr
|
||
term - unsignedexpr
|
||
term ::= factor
|
||
factor * term
|
||
factor / term
|
||
factor ::= var
|
||
number
|
||
( expression )
|
||
function
|
||
function ::= RND ( expression )
|
||
USR ( exprlist )
|
||
number ::= digit
|
||
digit number
|
||
separator ::= , ! ;
|
||
var ::= A ! B ! ... ! Y ! Z
|
||
digit ::= 0 ! 1 2 ! ... ! 9
|
||
relop ::= < ! > ! = ! <= ! >= ! <> ! ><
|
||
|
||
|
||
|
||
16
|
||
|
||
|
||
A P P E N D I X C
|
||
|
||
IMPLEMENTING I/O ROUTINES
|
||
|
||
COSMAC
|
||
|
||
COSMAC TINY occupies the same space as 6800 TINY -- 0100-08FF.
|
||
Similarly, the general parameters occupy 0020-00B7, as defined in
|
||
the manual. However, COSMAC TINY also uses locations 0011-001F to
|
||
contain copies of interpreter parameters and other run-time data; do
|
||
not attempt to use these locations while running TINY.
|
||
|
||
Like all Itty Bitty Computer software, COSMAC TINY contains no I/O
|
||
instructions (nor references to Q or EF1-4), no interrupt enables or
|
||
disables, and no references to an operating system. The three jumps
|
||
(LBR instructions) at 0106, 0109, and 010C provide all necessary
|
||
I/O, as defined in the manual. If you are using UT3 or UT4, you may
|
||
insert the following LBR instructions, which jump to the necessary
|
||
interface routines:
|
||
|
||
.. LINKS TO UT3/4
|
||
0106 C0076F LBR UTIN
|
||
0109 C00776 LBR UTOUT
|
||
010C C00766 LBR UTBRK
|
||
|
||
If you are not using the RCA monitor, you must write your own I/O
|
||
routines. For this the standard subroutine call and return linkages
|
||
are used, except that D is preserved through calls and returns by
|
||
storing it in RF.1. Registers R2-RB and RD contain essential
|
||
interpreter data, and if the I/O routines make any use of any of
|
||
them they should be saved and restored. Note however, that R2-R6
|
||
are defined in the customary way and may be used to nest subroutine
|
||
calls if needed. R0, R1, RC, RE and RF are available for use by the
|
||
I/O routines, as is memory under R2. Both the call and return
|
||
linkages modify X and the I/O data character is passed in the
|
||
accumulator ("D", not RD).
|
||
|
||
After connecting TINY to the I/O routines, start the processor at
|
||
0100 (the Cold Start). Do not attempt to use the Warm Start without
|
||
entering the Cold Start at least once to set up memory from
|
||
0011-0023. Any register may be serving as program counter when
|
||
entering either the Cold Start or the Warm Start.
|
||
|
||
The USR function works the same way as described in the manual,
|
||
except that the second argument in the call is loaded into R8, and
|
||
the third argument is loaded into RA with the least significant
|
||
byte also in the Accumulator. On return RA.1 and the accumulator
|
||
contain the function value (RA.0 is ignored). The machine language
|
||
subroutine must exit by a SEP R5 instruction. USR machine language
|
||
subroutines may use R0, R1, R8, RA, RC-RF, so long as these do not
|
||
conflict with I/O routine assignments. TINY BASIC makes no internal
|
||
use of R0, R1, RC, or RE.
|
||
|
||
RCA Corporation funded the development of COSMAC TINY BASIC, and it
|
||
is by RCA's permission that it is made available.
|
||
|
||
17
|
||
If you do not have access to a monitor in ROM with ASCII I/O
|
||
built in, you will have to write your own I/O routines. Most likely
|
||
you have something connected to a parallel port for the keyboard
|
||
input; output may be some parallel port also, or you may want to
|
||
use the 1861 video display for a gross dot-matrix kind of text
|
||
display. For the moment, let's assume you have parallel ports,
|
||
Port C (N=1100) for input, and port 4 (N=0100) for output. Assume
|
||
also that EF4 controls both input and output. This is the situation
|
||
you would have if you took an ordinary ELF and used the hex input
|
||
and display with the single "input" button to step through the
|
||
characters. You need for this configuration, two routines, which
|
||
might look something like this:
|
||
0106 C0 00E0 LBR KEYIN
|
||
0109 C0 00E7 LBR DISPL
|
||
...
|
||
00E0 3FE0 KEYIN BN4 *
|
||
00E2 E2 SEX 2
|
||
00E3 6C INP 4
|
||
00E4 37E4 B4 *
|
||
00E6 68 LSKP
|
||
00E7 3FE7 DISPL BN4 *
|
||
00E9 E2 SEX 2
|
||
00EA 73 STXD
|
||
00EB 52 STR 2
|
||
00EC 64 OUT 4
|
||
00ED 37ED B4 *
|
||
00EF D5 SEP 5
|
||
Of course if you have a keyboard on Port F you will change
|
||
the INP instruction to match; if the keyboard pulls EF3 down, then
|
||
you must change the first pair of BN4/B4 instructions to BN3/B3
|
||
instructions and change the LSKP to a NOP (C4 or E2). If your
|
||
input comes from some device that already displayed the character
|
||
typed, then change the LSKP to a Return (D5).
|
||
Similarly, if the output is to a different port you must
|
||
change the OUT instruction to fit it, and the second pair of BN4/B4
|
||
instructions to match the control line being used. Notice that
|
||
the LSKP instruction is only there to prevent your waiting on the
|
||
EF4 line twice for each keyin, and should be removed (changed to
|
||
a NOP) as soon as you connect up real input and output ports.
|
||
Many 1802 systems come equipped with a video output using
|
||
the 1861 chip. If you have this, you should get a copy of the
|
||
February and April 1979 issues of KILOBAUD MICROCOMPUTING (formerly
|
||
just KILOBAUD). I have a two-part article published in these two
|
||
issues which explains how to put text on the 1861 graphics display,
|
||
with particular emphasis on how to connect it to TINY BASIC.
|
||
So far I have not mentioned the Break test. If you leave
|
||
that part unchanged, Tiny will work just fine, but you cannot stop
|
||
a listing or a program that is getting too long. After you get
|
||
your keyboard and display connected up and working, you may want
|
||
to use EF4 (or some other flag) as a Break input. It is possible
|
||
to use the same flag for Break as for "input ready", if you want
|
||
Tiny to stop executing when you press a key on your keyboard (this
|
||
does not affect the INPUT instruction, which is obviously waiting
|
||
for that keyin). This code will do that:
|
||
010C C000F0 LBR BRKT
|
||
...
|
||
00F0 FC00 BRKT ADI 0
|
||
00F2 3FF6 BN4 EXIT
|
||
00F4 FF00 SMI 0
|
||
00F6 D5 EXIT SEP R5
|
||
Notice that the only function of this routine is to set the
|
||
Carry (DF) when EF4 is true (low) and clear it otherwise.
|
||
|
||
18
|
||
|
||
KIM
|
||
|
||
The Teletype I/O routines in the MOS Technology KIM system may
|
||
be used for the character input and output requirements of TINY BASIC
|
||
6502. The following break routine is included in Tiny to test the
|
||
serial data line at 1740; Since TINY BASIC 6502 does not use the
|
||
lower part of memory page 01, the break test routine is ORG'ed to
|
||
execute in that space:
|
||
|
||
; BREAK TEST FOR KIM
|
||
0100 AD4017 KIMBT LDA KTTY LOOK AT TTY
|
||
0103 18 CLC C=O IF IDLE
|
||
0104 300E BMI KIMX IDLE
|
||
0106 AD4017 LDA KTTY WAIT FOR END
|
||
0109 10FB BPL *-3
|
||
010B 200E01 KLDY JSR *+3
|
||
010E A9FF LDA #255 DELAY 2 RUBOUT TIMES
|
||
0110 20A01E JSR OUTCH
|
||
0113 38 SEC C=1 IF BREAK
|
||
0114 60 KIMX RTS
|
||
|
||
To run TINY BASIC 6502 load the paper tape into your Teletype
|
||
reader, type "L", and turn on the reader. Then key in the following
|
||
Jumps:
|
||
|
||
; JUMPS TO KIM
|
||
0206 4C5A1E JMP GETCH CHARACTER INPUT
|
||
0209 4CA01E JMP OUTCH CHARACTER OUTPUT
|
||
020C 4C0001 JMP KIMBT BREAK TEST
|
||
|
||
It is recommended that you save a copy of memory on tape
|
||
(0100-0114 and 0200-0AFF) before going any further. Or you may
|
||
prefer to save it on audio cassette. Set up the starting address for
|
||
Tiny at 0200, and type "G".
|
||
Because of the awkwardness of putting memory in the 4K gap left
|
||
in the KIM-1 system, an alternate version is available which executes
|
||
out of 2000-28FF. For this version the Cold Start is at 2000 and
|
||
other addresses are at 200x instead of 020x (cf. 010x in Appendix D).
|
||
|
||
|
||
JOLT or TIM
|
||
|
||
JOLT systems may not always have memory loaded in the space
|
||
from 0200 on up, so a special version has been prepared in which the
|
||
interpreter resides in the space 1000-18FF. This is the only
|
||
difference between the JOLT version and the KIM version, so if your
|
||
JOLT or TIM system has contiguous memory from Page 00 you may prefer
|
||
to use the KIM version to gain the extra memory space. Since the
|
||
serial data in the JOLT/TIM systems is not the same as KIM, a special
|
||
break test routine has also been provided for those systems:
|
||
|
||
; JOLT BREAK TEST
|
||
0115 A901 JOLBT LDA #1 LOOK AT TTY
|
||
0117 2C026E BIT JTTY
|
||
011A 18 CLC C=0 IF IDLE
|
||
|
||
|
||
19
|
||
|
||
011B F00E BEQ JOLTX IDLE
|
||
011D 2C026E BIT JTTY WAIT FOR END
|
||
0120 D0FB BNE *-3
|
||
0122 202501 JSR *+3 DELAY TWO CH TIMES
|
||
0125 A9FF LDA #255
|
||
0127 20C672 JSR WRT
|
||
012A 38 SEC C=1 = BREAK
|
||
012B 60 JOLTX RTS
|
||
|
||
To run, load the paper tape into your Teletype reader and type
|
||
"LH". Then key in the following Jumps:
|
||
|
||
; JUMPS TO JOLT/TIM
|
||
1006 4CE972 JMP RDT CHARACTER INPUT
|
||
1009 4CC672 JMP WRT CHARACTER OUTPUT
|
||
100C 4C1501 JMP JOLBT BREAK TEST
|
||
|
||
As with other versions, the Cold start is the beginning of the
|
||
program (1000).
|
||
|
||
|
||
|
||
MIKBUG
|
||
|
||
Systems that use MIKBUG (TM Motorola) for console I/O may use
|
||
the I/O routines in MIKBUG. The following break routine is provided
|
||
in Tiny to test the PIA at 8004:
|
||
|
||
* BREAK TEST FOR MIKBUG
|
||
|
||
B68004 BREAK LDA A PIAA LOOK AT PIA
|
||
0C CLC C=0 IF NONE
|
||
2B0D BMI EXIT
|
||
B68004 LDA A PIAA
|
||
2AFB BPL *-3 WAIT FOR END
|
||
8D00 BSR *+2
|
||
86FF LDA A #$FF DELAY ONE
|
||
BD0109 JSR TYPE CHARACTER TIME
|
||
0D SEC C=1 IF BREAK
|
||
39 EXIT RTS
|
||
|
||
To run, load the paper tape into your Teletype reader and type
|
||
"L". Then key in the following Jumps:
|
||
|
||
* JUMPS TO MIKBUG
|
||
ORG $0106
|
||
0106 7EE1AC JMP $E1AC CHARACTER INPUT
|
||
0109 7EE1D1 JMP $E1D1 CHARACTER OUTPUT
|
||
010C 7E08FD JMP $08FD BREAK TEST
|
||
|
||
It is recommended that you save a copy of memory on tape
|
||
(0100-08FF) before going any further. Set the starting address in
|
||
A048-A049 to 0100 and type "G". For your convenience the Cold Start
|
||
entry leaves the Warm start entry set up in the Mikbug stack, so that
|
||
after a reset a simple "G" command will result in a Warm start and
|
||
preserve the user programs.
|
||
|
||
20
|
||
|
||
OTHER
|
||
|
||
For standard systems (and for special systems with I/O other
|
||
than that provided), subroutines must be supplied by the user to
|
||
interface TINY to the operator. For ACIA input or output the
|
||
following routines may be used, or they may serve as examples for
|
||
your coding (6800 opcodes are shown). They should be assembled for
|
||
your ACIA address, and in some memory location which is not
|
||
contiguous with the TINY BASIC user program memory (which may be
|
||
destroyed by the Cold Start). If nothing else is available,
|
||
locations 00D8-00FF are not used by Tiny and may be used for this
|
||
purpose.
|
||
|
||
*
|
||
* ACIA I/O
|
||
*
|
||
B6XXXX BREAK LDA A ACIA
|
||
47 ASR A CHECK FOR TYPEIN
|
||
2406 BCC BRX NO, NOT BREAK
|
||
B6XXXY LDA A ACIA+1 GET IT
|
||
2601 BNE BRX NOT NULL IS BREAK
|
||
0C CLC IGNORE NULLS
|
||
39 BRX RTS
|
||
B6XXXX INPUT LDA A ACIA
|
||
47 ASR A
|
||
24FA BCC INPUT WAIT FOR A CHARACTER
|
||
B6XXXY LDA A ACIA+1 GET IT
|
||
36 OUTPUT PSH A SAVE CHARACTER
|
||
B6XXXX LDA A ACIA
|
||
8402 AND A #2 WAIT FOR READY
|
||
27F9 BEQ OUTPUT+1
|
||
32 PUL A
|
||
B7XXXY STA A ACIA+1 OUTPUT CHARACTER
|
||
39 RTS
|
||
|
||
Note that this routine will accept any non-null character
|
||
typein as a break. Alternatively we could look at the Framing Error
|
||
status, but if a character has been input this status will not show
|
||
up until that character is read in, rendering it ineffective in some
|
||
cases. Nulls are excepted as break characters since one or more of
|
||
them may follow the carriage return in an input tape, and still be
|
||
pending. Note that for this to work properly, the pad character
|
||
defined in location 0111 should be set to NULL (hex 00).
|
||
|
||
The 6800 "R" version of TINY BASIC includes these routines in
|
||
the code, as shown here. Locations 08FA-08FC contain a JMP to the
|
||
break test at the beginning of this block. You should alter the ACIA
|
||
addresses to suit your system before using the subroutines.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
21
|
||
|
||
CRT OR TVT
|
||
|
||
If a TV Typewriter is used for I/O it may be desirable to
|
||
remove excess control characters from the output stream. All
|
||
controls except Carriage Return may be removed by the following
|
||
instructions at the beginning of the output subroutine (6800 opcodes
|
||
shown):
|
||
|
||
39 RTS
|
||
810A OUTPUT CMP A #0A
|
||
2FFB BLE OUTPUT-1
|
||
|
||
Only nulls, Rubouts, X-ON and X-OFF may be deleted by changing the
|
||
CMP to a TST A. Nulls may be passed through by also changing the BLE
|
||
to a BMI.
|
||
|
||
Some TV Typewriters do not scroll up when the cursor reaches
|
||
the bottom of the screen, but rather wrap the cursor around to the
|
||
top of the screen, writing over the previously displayed data. With
|
||
this kind of display it is essential that the I/O routines (or the
|
||
hardware) clear to the end of the line whenever a CR-LF is output,
|
||
so that previous data does not interfere with the new. If your I/O
|
||
routines are fixed in ROM, some sort of preprocessor may be required
|
||
to recognize output CR's and convert them to the appropriate sequence
|
||
of control functions. It may also be necessary to trap input CR's
|
||
(suppressing their echo) since Tiny generally responds with both
|
||
another CR and a linefeed.
|
||
|
||
Some users prefer to concatenate all output into one "line" of
|
||
print, using the terminal comma or semicolon to suppress the line
|
||
breaks. Since TINY was designed to limit line lengths to less than
|
||
128 characters, if this sort of concatenation is attempted it will
|
||
appear that TINY has quit running. To eliminate the print
|
||
suppression the most significant two bits of the print control byte
|
||
(location 00BF in most versions) may be cleared to zero periodically
|
||
with the USR function or in the output driver routine. The least
|
||
significant three bits of this same byte are used for the "comma
|
||
spacing" in the PRINT statement, and should be left unaltered.
|
||
|
||
|
||
|
||
CASSETTE I/O
|
||
|
||
Officially, TINY only speaks to one peripheral--the console.
|
||
However a certain amount of file storage may be simulated by
|
||
attaching these peripherals (such as cassette systems) to the
|
||
character input and output routines. If the same electrical and
|
||
software interface is used this is very easy. Otherwise the I/O
|
||
drivers will require special routines to recognize control characters
|
||
in the input and output data for setting internal switches which
|
||
select one of several peripherals. The USR function may also be
|
||
used either to directly call I/O routines or to alter switches in
|
||
memory.
|
||
|
||
|
||
|
||
|
||
22
|
||
|
||
|
||
|
||
|
||
|
||
A P P E N D I X D
|
||
|
||
LOW MEMORY MAP
|
||
|
||
|
||
LOCATION SIGNIFICANCE
|
||
-------- ------------
|
||
|
||
0000-000F Not used by any version of TINY
|
||
0011-001F COSMAC version temporaries
|
||
0020-0021 Lowest address of user program space
|
||
0022-0023 Highest address of program space
|
||
0024-0025 Program end + stack reserve
|
||
0026-0027 Top of GOSUB stack
|
||
0028-002F Interpreter parameters
|
||
0030-007F Input line buffer & Computation stack
|
||
0080-0081 Random Number Generator workspace
|
||
0082-0083 Variable "A"
|
||
0084-0085 Variable "B"
|
||
... ...
|
||
00B4-00B5 Variable "Z"
|
||
00B6-00C7 Interpreter temporaries
|
||
00B8 Start of User program (PROTO)
|
||
00C8-00D7 Sphere parameters (not 0020-002F)
|
||
00D8-00FF Unused by standard version
|
||
|
||
0100 Cold Start entry point (6800)
|
||
0103 Warm Start entry point
|
||
0106-0108 JMP (or JSR) to character input
|
||
0109-010B JMP to character output
|
||
010C-010E JMP to Break test
|
||
010F Backspace code
|
||
0110 Line Cancel code
|
||
0111 Pad character
|
||
0112 Tape Mode Enable flag (hex 80 = enabled)
|
||
0113 Spare stack size
|
||
0114 Subroutine to read one Byte
|
||
from RAM to A (address in X)
|
||
0118 Subroutine to store A into RAM
|
||
at address in X
|
||
|
||
0900 Beginning of User program (6800)
|
||
|
||
Note that some of these addresses apply to the standard 6800 version.
|
||
For other versions addresses above 0100 should be read as addresses
|
||
above their respective starting address.
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
23
|
||
|
||
A P P E N D I X E
|
||
|
||
AN EXAMPLE PROGRAM
|
||
|
||
|
||
10 REM DISPLAY 64 RANDOM NUMBERS < 100 ON 8 LINES
|
||
20 LET I=0
|
||
30 PRINT RND (100),
|
||
40 LET I=I+1
|
||
50 IF I/8*8=I THEN PRINT
|
||
60 IF I<64 THEN GOTO 30
|
||
70 END
|
||
|
||
|
||
100 REM PRINT HEX MEMORY DUMP
|
||
109 REM INITIALIZE
|
||
110 A=-10
|
||
120 B=-11
|
||
130 C=-12
|
||
140 D=-13
|
||
150 E=-14
|
||
160 F=-15
|
||
170 X = -1
|
||
175 O = 0
|
||
180 LET S = 256
|
||
190 REMARK: S IS BEGINNING OF TINY (IN DECIMAL)
|
||
200 REM GET (HEX) ADDRESSES
|
||
210 PRINT "DUMP: L,U";
|
||
215 REM INPUT STARTING ADDRESS IN HEX
|
||
220 GOSUB 500
|
||
230 L=N
|
||
235 REM INPUT ENDING ADDRESS IN HEX
|
||
240 GOSUB 500
|
||
250 U=N
|
||
275 REM TYPE OUT ADDRESS
|
||
280 GOSUB 450
|
||
290 REM GET MEMORY BYTE
|
||
300 LET N = USR (S+20,L)
|
||
305 REM CONVERT IT TO HEX
|
||
310 LET M = N/16
|
||
320 LET N = N-M*16
|
||
330 PRINT " ";
|
||
335 REM PRINT IT
|
||
340 GOSUB 400+M+M
|
||
350 GOSUB 400+N+N
|
||
355 REM END?
|
||
360 IF L=U GO TO 390
|
||
365 L=L+1
|
||
370 IF L/16*16 = L GOTO 280
|
||
375 REM DO 16 BYTES PER LINE
|
||
380 GO TO 300
|
||
390 PRINT
|
||
395 END
|
||
399 PRINT ONE HEX DIGIT
|
||
400 PRINT O;
|
||
|
||
|
||
24
|
||
|
||
401 RETURN
|
||
402 PRINT 1;
|
||
403 RETURN
|
||
404 PRINT 2;
|
||
405 RETURN
|
||
406 PRINT 3;
|
||
407 RETURN
|
||
408 PRINT 4;
|
||
409 RETURN
|
||
410 PRINT 5;
|
||
411 RETURN
|
||
412 PRINT 6;
|
||
413 RETURN
|
||
414 PRINT 7;
|
||
415 RETURN
|
||
416 PRINT 8;
|
||
417 RETURN
|
||
418 PRINT 9;
|
||
419 RETURN
|
||
420 PRINT "A";
|
||
421 RETURN
|
||
422 PRINT "B";
|
||
423 RETURN
|
||
424 PRINT "C";
|
||
425 RETURN
|
||
426 PRINT "D";
|
||
427 RETURN
|
||
428 PRINT "E";
|
||
429 RETURN
|
||
430 PRINT "F";
|
||
431 RETURN
|
||
440 REM PRINT HEX ADDRESS
|
||
450 PRINT
|
||
455 REM CONVERT IT TO HEX
|
||
460 N = L/4096
|
||
470 IF L<0 N=(L-32768)/4096+8
|
||
480 GOSUB 400+N+N
|
||
483 LET N=(L-N*4096)
|
||
486 GOSUB 400+N/256*2
|
||
490 GOSUB 400+(N-N/256*256)/16*2
|
||
495 GOTO 400+(N-N/16*16)*2
|
||
496 GOTO=GOSUB,RETURN
|
||
500 REM INPUT HEX NUMBER
|
||
501 REM FORMAT IS NNNNX
|
||
502 REM WHERE "N" IS ANY HEX DIGIT
|
||
505 N=0
|
||
509 REM INPUT LETTER OR STRING OF DIGITS
|
||
510 INPUT R
|
||
520 IF R=X RETURN
|
||
525 REM CHECK FOR ERROR
|
||
530 IF R>9999 THEN PRINT "BAD HEX ADDRESS
|
||
531 REM NOTE ERROR STOP ON LINE 530 (ON PURPOSE!)
|
||
535 REM CONVERT INPUT DECIMAL DIGITS TO HEX
|
||
540 IF R>999 THEN N=N*16
|
||
545 IF R>99 THEN N=N*16
|
||
550 IF R>9 THEN N=N*16
|
||
|
||
25
|
||
|
||
555 IF R>0 THEN R=R+R/1000*1536+R/100*96+R/10*6
|
||
559 REM PICK UP NON-DECIMAL DIGIT LETTERS
|
||
560 IF R<0 THEN LET R=-R
|
||
565 REM ADD NEW DIGIT TO PREVIOUS NUMBER
|
||
570 LET N=N*16+R
|
||
580 GOTO 510
|
||
590 NOTE: DON'T NEED END HERE
|
||
|
||
|
||
1000 TO RUN RANDOM NUMBER PROGRAM, TYPE "RUN"
|
||
1010 IT WILL TYPE 8 LINES THEN STOP.
|
||
1020 TO RUN HEX DUMP PROGRAM TYPE "GOTO 100"
|
||
1030 IT WILL ASK FOR INPUT, TYPE 2 HEX ADDRESSES
|
||
1040 EACH TERMINATED BY THE LETTER X,
|
||
1050 AND SEPARATED BY A COMMA
|
||
1055 (TYPE ALL ZEROS AS LETTER OH).
|
||
1060 THE PROGRAM WILL DUMP MEMORY BETWEEN
|
||
1070 THOSE TWO ADDRESSES, INCLUSIVE.
|
||
1080 EXAMPLE:
|
||
1090 :GOTO 100
|
||
1100 DUMP: L,U? AO3EX,AO46X
|
||
1110 A03E EE FF
|
||
1120 A040 00 11 22 33 44 55 66
|
||
1130 IF THE RANDOM NUMBER PROGRAM
|
||
1140 IS REMOVED, OR IF YOU TYPE IN
|
||
1150 :1 GOTO 100
|
||
1160 THEN YOU CAN GET THE SAME DUMP BY TYPING
|
||
1170 :RUN,AO3EX,AO46X
|
||
1180 .
|
||
1190 NOTE THAT THIS PROGRAM DEMONSTRATES NEARLY
|
||
1200 EVERY FEATURE AVAILABLE IN TINY BASIC.
|
||
|
||
|
||
|
||
REMARK: TO FIND OUT HOW MUCH PROGRAM SPACE
|
||
REM... YOU HAVE LEFT, TYPE:
|
||
LET I=0
|
||
1 LET I=I+2
|
||
2 GOSUB 1
|
||
RUN
|
||
REMARK: AFTER A FEW SECONDS, THIS WILL STOP
|
||
REM... WITH AN ERROR; THEN TYPE:
|
||
END
|
||
PRINT "THERE ARE ";I;" BYTES LEFT"
|
||
|
||
|
||
REM: TO EXIT FROM TINY BASIC TO YOUR MONITOR/DEBUGGER,
|
||
LET S=256
|
||
REM (S AS IN LINE 180 ABOVE)
|
||
LET B=0
|
||
IF P=6800 THEN LET B=63
|
||
REM: B IS SWI OR BRK INSTRUCTION
|
||
LET A = USR (S+24,0,B) + USR (0)
|
||
REM: THE FIRST CALL STORES A BREAK IN 0000
|
||
REM... THE SECOND CALL JUMPS TO IT.
|
||
|
||
|
||
26 |