BEEBDOC

[tom_seddon]

A rather odd item found on an EPROM in a B+128: in the lower 8 KB, beebmon 1.00 (see http://bbc.nvg.org/rom/Watford/util/BEEBMon-1.00.rom - also found in the TOSEC collection), and in the upper 8 KB, Disc Doctor 1.0B (see https://acorn.huininga.nl/pub/roms/Comp ... 201.0B.rom - I think?) relocated to run at $a000. Has this relocated Disc Doctor been seen before?!

The beebmon service routine at $8003 does a jmp $a000, and at $a000 there's jsr $8028 (original beebmon service routine) then jmp $a065 (discdoc service routine).

Most of the different bytes look to be address changes, but there's also bit here, which looks like it might have been some kind of checksum routine: (< is the acorn.huininga.nl ROM, > is the top 8 KB of this new ROM)

Code: Select all

< 00000100: 02 c9 20 60 a2 00 8a 18 7d 01 80 e8 d0 fa c9 76 .. `....}......v
< 00000110: d0 01 60 78 d0 fd a6 7d a9 00 9d 00 0a 6c 00 01 ..`x...}.....l..
---
> 00002100: 02 c9 20 60 00 54 48 49 53 20 53 50 41 43 45 20 .. `.THIS SPACE
> 00002110: 46 52 45 45 21 21 a6 7d a9 00 9d 00 0a 6c 00 01 FREE!!.}.....l..

I'm not at all familiar with beebmon, but you can do *MONITOR and get something.

I never used anything in DIsc Doctor other than *DIS and *MZAP, but they both seem to work.

--Tom

[jgharston]

Yes, it was quite common, there were various collections of 8K+8K ROMs around with one relocated to &A000. Ones I've seen have been combinations of DiskDoc, various Basic utilities, various "utility" utilities, various extensions. See here for some examples.

I can't remember where I first saw them, but it inspired me to write a way of combining any number of (almost) arbitary ROMs together in the same way by including a relocation table with the "Sideways Module" image. Alas, I sent the article I wrote to Micro User too late, by then they weren't interested in Beeb stuff.