[N8VEM: 16153] 8MHz PPI with 10MHz Z80

[p***@public.gmane.org]

Gents,

I'm looking around to get a 8255 PPI for my SBC V2. The available DIP ones are 5MHz and 8MHz. My Z80 is 10MHz and I'm wondering whether the PPI will work properly with this CPU clock rate.
Looking at SBC V2 schematic shows that the PPI is mapped in the IO address space, and if I remember correctly, Z80 had 1-cycle wait-state when doing IO operations, so this could possibly do the job. From another perspective, even with the wait-state, the setup & hold times will still be different and shorter than expected by the 8MHz PPI (this non-working).

What's your experience with the PPI and CPU clock rate, and do you think that 8MHz PPI will work with 10MHz Z80?

Regards,
picmaster

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[Mike Petchey]

Hi picmaster
I am running my Z80 at 10Mhz and have been using a CP82C55A5Z

[Mike Petchey]

Sorry I posted previously before finishing the post.

I am running my Z80 at 10Mhz and have been using a CP82C55A5Z which

according to the spec is 5MHz. I have had no problems. I am running the
DSKY board off it which I think exercises it pretty well.

regards

Mike pethchey

[Wayne Warthen]

I run my Zeta at 20MHz with a 10MHz 8255. I have also run my SBC V2 at
16MHz with an 8MHz 8255. In both cases the PPI is heavily used for disk
I/O. No problems at all.

--Wayne

Post by p***@public.gmane.org
Gents,
I'm looking around to get a 8255 PPI for my SBC V2. The available DIP ones
are 5MHz and 8MHz. My Z80 is 10MHz and I'm wondering whether the PPI will
work properly with this CPU clock rate.
Looking at SBC V2 schematic shows that the PPI is mapped in the IO address
space, and if I remember correctly, Z80 had 1-cycle wait-state when doing
IO operations, so this could possibly do the job. From another perspective,
even with the wait-state, the setup & hold times will still be different
and shorter than expected by the 8MHz PPI (this non-working).
What's your experience with the PPI and CPU clock rate, and do you think
that 8MHz PPI will work with 10MHz Z80?
Regards,
picmaster
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