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Tinyloc
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Wishing to experiment with the Commodore 128 CP/M mode, I first
tried to run the LOCCALC.BAS program with the famous Microsoft
MBASIC interpreter under CP/M.
The software LOCCALC.BAS, developed in the CBM Basic V2 dialect,
works without modifications with the MBASIC interpreter, with the
only precaution of typing capital letters as inputs.
This fact is not surprising because Commodore Basics are directly
derived from MBASIC and they share most of their syntax with it.
In particular Basic V2 is a subset of MBASIC and it is highly
portable not only between Commodore machines, but also towards
BASICA/GW-BASIC, the latter widely used on IBM PCs and compatibles
of the time.
I wanted to run LOCCALC.BAS in a free CP/M environment, but
unfortunately it is still unclear today whether the MBASIC
interpreter is free software or not, despite Microsoft having
publicly released the source codes.
So I decided to develop a new program that could work with the
public domain Tiny Basic interpreter, a version of which I found
on the internet compiled for the CP/M operating system.
Tiny Basic, however, has several limitations compared to Basic V2,
including the use of only integer numbers, no strings, only
numeric input supported, the lack of possibility to manage the
ASCII encoding of characters, the absence of AND and OR operators
in the IF statements.
I therefore wrote a very limited program, Tinyloc, which only
allows you to calculate the qth locator starting from the
geographical coordinates in DMS format.
Given the limitations of the interpreter, I consider this a good
result.
Here is the link to the source code of Tinyloc: tinyloc.txt
Here is the link to a bootable disk image in d71 format with the
program Tinyloc itself and the Tiny Basic interpreter: tinyloc.d71
To load, run and use Tinyloc follow the instructions reported below.
Screenshots/usage
To load and start the program Tinyloc with the VICE Commodore
emulator:
0 - Start the VICE Commodore emulator (x128)
1 - Attach the disk image "tinyloc.d71" to drive 8 (must be a 1571
disk drive) and type BOOT at the C128 prompt.
2 - Once the CP/M operating system is loaded, type DIR at the CP/M
prompt to view the contents of the disk
3 - Type TINYBAS at the CP/M prompt to load the Tiny Basic
interpreter
4 - Once the Basic interpreter is loaded, type LOAD TINYLOC at the
interpreter's prompt (all capital tetters, file name without
extension and without quotes) to load the program
5 - Type RUN (all capital letters) at the interpreter's prompt to
run the program
Loading and running Tinyloc under CP/M with
VICE emulating a C128 (CP/M mode)
Enter longitude and latitude as required by the program. The
program prints the corresponding qth locator on the screen.
Entering longitude and latitude; The program
Tinyloc calculates and prints the locator
To exit the Basic interpreter and return to the operating system,
type BYE.
Have fun!
