Paul Schlyter wrote: >In article , >Bill Garber wrote: >From: "Bill Garber" >Subject: Re: Dos CP/M on a Z80 card require an 80 column card to work? > >> "Paul Schlyter" wrote in message >> news:bkfqoi$s9q$1@merope.saaf.se... >> >>> The dip switches on the Z80 card may have been set improperly -- all >>> 4 of them should be set to the OFF position to run Apple CP/M. >> >> Come to think of that. I do need switch 4 set to ON to run it >> with my 80 column card in place. Sorry that I didn't remember >> that part. > >Strange --- my Z80 Softcard always worked with an 80-column card with >all the 4 Softcard dip switches set to OFF. It's a Microsoft >Softcard, and the 80-column card was a Videx card. According to information on the web: "If your card is a Microsoft Softcard (easily identifiable by the words "MICROSOFT SOFTCARD" printed in the upper left corner of the component side), or a clone thereof, then OFF is the correct position for all four switches (Softcard CP/M doesn't use any of the features that the switches control). The Softcard switch settings are as follows: Switch 1: OFF = Address translation occurs (Z80 address 0000H corresponds to 6502 address $1000) ON = No address translation (Z80 address = 6502 address) Switch 2: OFF = Softcard locks out all other DMA devices when Z80 is active ON = DMA signal from higher slot can interrupt Softcard Switch 3: OFF = Softcard ignores NMI ON = NMI causes Z80 non-maskable interrupt Switch 4: OFF = Softcard ignores IRQ ON = IRQ causes Z80 interrupt Softcard CP/M expects to find addresses remapped, so switch 1 should be left off. Most Softcard CP/M programs can't handle interrupts, so switches 3 and 4 should be left off too. Turning switch 2 on probably won't hurt CP/M, but leaving it off is consistant with CP/M's philosophy of letting the 6502 handle most I/O." So all switches should be off. -michael Check out amazing quality sound for 8-bit Apples on my Home page: http://members.aol.com/MJMahon/