9 Feb
2018
9 Feb
'18
1:24 p.m.
On 02/09/2018 12:26 PM, allison via cctalk wrote:
IBM PC early also did that... other vendors of the
8088 didn't work
in the 64K and early 256K IBM PCs due to a slight timing variation
that reputedly intel helped design in. One gate fixed it but it was
undocumented thing you could getaway with only with Intel 8088s.
Hmm, must have been *very* early PCs, as mine had an AMD 8088 in it--but
wasn't AMD a licensee of the Intel part? But then, so was NEC.
I think IMSAI used the "different" NEC 8080s in their floppy controller,
as they were inexpensive (because of the incompatibility) and in the
particular application, it didn't matter.
I do recall very early 8085s having a "reset" bug, necessitating some
external glue, but it's been too long for me to remember the details.
--Chuck