10 Dec
2016
10 Dec
'16
11:49 a.m.
-----Oorspronkelijk bericht-----
Van: cctech [mailto:cctech-bounces at classiccmp.org] Namens Paul Berger
Verzonden: zaterdag 10 december 2016 1:37
Aan: General Discussion: On-Topic and Off-Topic Posts
Onderwerp: Re: Flex Disc options for the HP 9825
Some time ago there was a discussion about the elusive 98228A ROM that
supports both the 9885 and 9895 diskette drive units on a 9825T, well good
news! A fellow MoHPC member David Ramsey very kindly loaned me his, and
with a little careful reading of the service manual along with studying
Tony
Duell's schematic I got a good idea of how it
work, and observing the
memory
bus using a logic analyzer confirmed how it worked. I
was able to dump
the
ROM using GPIO cards in a 9920 to simulate the memory
bus, I actually went
on
and dumped all the ROMs in the 9825T as well as a
couple other I had. I
have
successfully created a clone of the ROM and have even
fit it into a a ROM
shell.
I am going to try creating a PCB for it too, what I
have now is just hand
wired,
but it works. In the end the ROM module did not turn
out to be very
complicated. I am just in the process of documenting my project and will
release a package soon with full documentation and most importantly the
ROM
image. I plan to donate my package along with all of
my ROM images to
hpmuseum.net.
Paul.
Great work Paul.
-Rik