by Charles Bachand
The Low Cost Printer Interface article by Paul Swanson that appeared in ANALOG issue #16 has produced highly favorable remarks from our readership and should encourage the submission of more hardware/software articles in the future. Unfortunately, a very small number of our readers found out that the software would not function properly for them. Those having problems have been cassette-only users. Some were good enough to point out that when they tried the interface and software on a friend's computer which included a disk drive, the whole thing worked perfectly! We re-examined the machine language software that drives the interface. The software will not work with a cassette-only system without the following changes:
230 POKE 12,216:POKE 13,6:POKE 9,1
360 DATA 208,244,169,128,153,27,3,169,
6,153,28,3,96The added POKE statement at the end of line 230 tricks the computer into thinking that software has been booted from a disk. The DOSINI vector will now work properly. The last byte in line 360 represents a RTS instruction to return control back to BASIC instead of jumping to DOS initialization code that is not there.