HP7957 emulation on HP9000/300 system

[francesco franzini]

Hi, i just built two MFM emulator, they both work very well, to me this project is just amazing, i did several tests on HP9000 system with very good results, i made two different HP9133 working but I still have problem to emulate the HP7957 drive, i tried to collect useful information about the hard disk used on this drive without success and i got no response at all fron the emulator during the inizialitation of the HP7957 unit.

Unfortunately my HP7957 is without hard drive and on the manuals i haven't found any info, as far I understood the drive on this unit is RLL encoded and the command set is ESDI, since i have little knowledge about encoding system and hard disk commad set i would like to know if the mfm emulator can work on this type of unit.

Thank you

Francesco

[David Gesswein]

On Mon, Jul 18, 2022 at 01:26:21AM -0700, francesco franzini wrote:
> Hi, i just built two MFM emulator, they both work very well, to me this
> project is just amazing,

Thanks. Did you have the PCB fabbed yourself?

> as far I understood the drive on this unit is RLL encoded
> and the command set is ESDI, since i have little knowledge about encoding
> system and hard disk commad set i would like to know if the mfm emulator
> can work on this type of unit.
>

No. ESDI can't work with this hardware. RLL has been something I've wanted
to add but haven't ever gotten a big enough chunk of time. There have been
a few people talking about ESDI emulator but I have not heard of any actually
working.

[francesco franzini]

Yes, i made by myself B revision pcb using your gerber files.

I found some documentation about ESDI and i realized that the interface is very different.

Unfortunately the documentation available about  HP7957 drive hardware is not complete and the hard disk seems to be custom made for HP with no commercial equivalent, never mind, i have two HP9133 double drive and they are more than enough for me.

Thank you

Francesco

[David Gesswein]

This seems to have a reasonable amount of info.
http://www.hpmuseum.net/document.php?hwfile=5043

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