80-Bus News

  

July–October 1982, Volume 1, Issue 3











Page 18 of 51











EXAMPLE 2
MACHINE CODE SUBROUTINE TO GET COORDINATES

EXAMPLE 3 – MBASIC

This Basic program, which is well sprinkled with REM statements, is provided as a guide that others can follow. As it is purely for demonstration purposes the program has been coded for clarity.

Note: In line 1020 ADDR holds the address of where the USR routine is stored. Nascom Basic/Nas-Sys users should pick an area within the workspace RAM (0C80H-0FFFH). GM809 users on a Nascom can use the workspace RAM as well, though in their case it is located at 0FC00H-0FFFFH. (NB Your CP/M system size should be 63K or less if you intend to use the workspace RAM).

For Multiboard users the problem is slightly more complex. Either a CP/M system can be used that is 1K less than the available memory size, or the /M option can be used when loading MBASIC to leave an area of RAM free for the machine code program.


This is an OCR’d version of the scanned page and likely contains recognition errors.











Page 18 of 51