"Dana L. Smith" <smithd@unc.uucp> (11/17/84)
I'm trying to use MODEM7 with an Apple II+ and an Apple Super Serial Card. I've tried writing my own code to talk to the serial card but so far have had no success. The card works fine but sometimes locks up and won't receive data properly. I know I'm doing something wrong but I can't figure out what it is. My code is just a Z80 version of the appropriate 6502 ROM code listed in the manual. Does anyone out there have a working overlay file for this configuration? Thanks in advance. smithd@unc
jimb@amd.UUCP (Jim Budler) (11/24/84)
In article <> "Dana L. Smith" <smithd@unc.uucp> writes: > >I'm trying to use MODEM7 with an Apple II+ and an Apple Super Serial Card. >I've tried writing my own code to talk to the serial card but so far >have had no success. The card works fine but sometimes locks up and won't >receive data properly. I know I'm doing something wrong but I can't >figure out what it is. My code is just a Z80 version of the appropriate >6502 ROM code listed in the manual. > >Does anyone out there have a working overlay file for this configuration? > >Thanks in advance. > > >smithd@unc It may not be your code at all. Microsoft had the 6502 perform all I/O in the first place, rather than just switch on the Z80 and run, due to some differences in timing between the 6502/6255 and the Z80/6255. You are probably running into these. -- Jim Budler Advanced Micro Devices, Inc. (408) 982-6547 UUCPnet: {ucbvax,decwrl,ihnp4,allegra,intelca}!amd!jimb Compuserve: 72415,1200 The Source: STW265