Email: Password: Remember Me | Create Account (Free)

Back to Subject List

Old thread has been locked -- no new posts accepted in this thread
???
07/20/07 04:37
Read: times


 
#142058 - 6800 peripherals on 8052
Has anyone tried connecting a 6522 VIA, or any other 6800-bus compatible peripheral to an 8052?

The main difference is the handshaking used; the VIA has /CS, R//W, and the enable clock, E. When E is high a transfer is carried out based on R//W and the other bus signals, it's something akin to /MREQ on a Z80 I suppose. Normally this connects to a clock signal like the 6502 phase 2 clock, though I saw a Z80 design connect it to /IORQ.

I'm not sure how to generate these signals. R//W would be the equivalent of /RD and /WR XOR'd together, but to represent the idle state (both strobes high) the peripheral would have to be disabled, probably by gating /CS or E. Then there's the issue of how to derive E itself.

I know there are better I/O chips for this purpose that are suited for the 8052, but in this case I need two 8-bit bidirectional I/O ports with the direction controlled on a per-pin basis. The 8255 doesn't quite cut it, but the VIA is perfect.

List of 5 messages in thread
TopicAuthorDate
6800 peripherals on 8052            01/01/70 00:00      
   Some problems            01/01/70 00:00      
   What is it about the 6522 that you like?            01/01/70 00:00      
      Availability!            01/01/70 00:00      
         well ... maybe not so fast, but certainly useable            01/01/70 00:00      

Back to Subject List