INMC 80 News

  

February–April 1981, Issue 3











Page 12 of 55











Now the software, a table driven loop with nothing specific to a traffic light application, Each byte of the table is used as follows:

BIT   7 6 5 4 3 2 1 0
USE   R Y G <-delay->

Where R Y and G are the outputs to the LED drivers (1=on), and the lower 5 bits hold the number of seconds (approx) that the output is maintained for. The special code 00 denotes the end of list and causes the table pointer to be reset to the start, The program is relocatable and will run on NAS-SYS or T1 to T4 monitors, execute at E00:

KEYBOARD BITS

I was surprised to see in INMC80 1 that Martin Dyer was using the PIO and push button switches for the controls on a space invaders game. The NASCOM keyboard is suitable for this job, providing the correct software is used to read it. The KBD routine does give information about keys that are held pressed, as anyone with a repeat keyboard will confirm. Whenever the routine is called it updates the bit map, KMAP from C01 to C09, where each bit in the map represents a key on the keyboard (1=pressed), Here’s a short program to tell you the byte and bit in KMAP for any one key as it is pressed, The program should run on NAS-SYS or any of T1 to T4 monitors, and is relocatable, execute at F00:


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











Page 12 of 55