[sebhc] Re: Re-creating actual floppies from archive

[Peter Shkabara]

I might pipe in at this point. When I made the 4MHz and 6MHz mods for the
H89, I found that 4MHz was fine with a few IC changes, but I ran into great
difficulties at 6MHz. The solution ended up being a software patch to have
the operating system drop operation back down to 2MHz when I/O access was
needed.

Peter Shkabara
----------------------------------
peter59 at sbcglobal.net
 

-----Original Message-----
It's been a long time, and I've forgotten the details. But I ran across it
when I was designing the H-1000 (a replacement CPU board for the H89). The
old 8250 had a bus fight problem with the Z80 at 4 MHz, and both new and old
8250 had problems at both 2 MHz and 4 MHz. National had an application note
that outlined the problem.

--
Delivered by the SEBHC Mailing List