UNIBUS M9312 ROM type identification

Don North north at alum.mit.edu
Wed Sep 7 01:55:36 CDT 2016

On 9/6/2016 9:23 AM, JP Hindin wrote:
> Greetings;
> My googlefu is failing me and I was wondering if someone might be able to help 
> me identify one of the boot ROMs present in an M9312 bootstrap/term board. The 
> board has three ROMs, an RX01 (042130), an RX02 (042131) and then a mystery 
> code - 043127.
> The M9312 ROM identification table does not list this ROM code - I suspect it 
> _might_ be for a DSD combined 8" drive and Winchester disk box, but I'm under 
> the impression this would appear as a DU device, and attempting to boot from 
> DU gets an ILL CMD, suggesting otherwise. I tried all of the other possible 
> mnemonics listed in the M9312 manual, so it doesn't appear to piggy-backing on 
> any of those either.
> My thanks;
>  - JP
Octal word 042130 decodes as ascii "DX", which is the M9312 boot mnemonic for 
the RX01 drive/RX11 controller combo.

Octal word 042131 decodes as ascii "DY", which is the M9312 boot mnemonic for 
the RX02 drive/RX211 controller combo.

Octal word 043127 decodes as ascii "FW", which is not a standard M9312 boot 
mnemonic. Probably a third party manufacturer custom boot prom.

FYI the above octal words are programmed in the first word of each boot PROM, so 
they are accessible at locations 773000,

You can find program listings and hex PROM images of all the known M9312 devices 
here:  http://www.ak6dn.com/PDP-11/M9312/, including the DX and DY PROMs.


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