r65c02p2 wrote: >--- In 6502ag@y..., "rey_bbs" <rey_bbs@y...> wrote: > > >>Is there a way to use 8255 in a 6502 computer instead of a 6522? >> >> >Howdy Guys, > >I've read the list discussion regarding 8255's and the 6502 and >thought I'd pipe up. I use 8255's with 6502 whenever I need lots >of I/O bits per package count. Interface is rather simple. I also use >NEC part Nr. D71055C which is a 8255 pin/program compatible CMOS >component that will work to 10 MHz. Also using 82C55 for battery >powered systems. All work quite reliably. > >The /RD and /WR signals for the 8255 I generate this way: > >/RD is 6502 R/W NAND Phi2 >/WR is 6502 INVERTED-R/W NAND Phi2 > >Easily accomplished with single quad NAND...I generally use these >same strobes for memory access and other buss connected device access. > > Regards All, > Brian >