Flex Disc options for the HP 9825
curiousmarc3 at gmail.com
Sat Dec 10 11:27:01 CST 2016
Fantastic! Can't wait for the info.
> On Dec 9, 2016, at 4:36 PM, Paul Berger <phb.hfx at gmail.com> wrote:
> 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.
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