Flex Disc options for the HP 9825

Rik Bos hp-fix at xs4all.nl
Sat Dec 10 13:49:44 CST 2016

> -----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
> Duell's schematic I got a good idea of how it work, and observing the
> bus using a logic analyzer confirmed how it worked.  I was able to dump
> ROM using GPIO cards in a 9920 to simulate the memory bus, I actually went
> and dumped all the ROMs in the 9825T as well as a couple other I had.  I
> successfully created a clone of the ROM and have even fit it into a a ROM
> I am going to try creating a PCB for it too, what I have now is just hand
> 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
> image.  I plan to donate my package along with all of my ROM images to
> hpmuseum.net.
> Paul.

Great work Paul.


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