8-bit acorn hardware • Re: Solidisk 256k 2/4Meg - &FE30/32

Thinking overnight and reading the Solidisk manuals again, I think it likely Solidisk 'capture' and do something with &FE30/32 on the 256/4meg board.

Well, they intercept FE30 to allow the RAM/ROM to be paged in. On the 2M128 they use FE34 to select how the memory is mapped (eg for shadow modes). Dunno about the 2/4Meg board. Based on that picture it looks like FE32 is the write-bank, FE30 is the read-bank and FE36 lets you flip which half of a 32K ROM was in use. It's also buggy code since it writes to FE30 without writing to F4 first.

If only I had a circuit diagram! Maybe a bit of reverse engineering?

There's been a fair bit of work done on this; search the forum. I have a vague memory that someone may even have done a recreation. Not sure.

Solidisk talk of the 'read-only' registers in &FE30/32

FE30 is write only.

In another publication they write to F4 & FE30, FE32 & FE62, as I have in my code.

The FE62 is the user port, and is for an earlier generation of Soldisk ram boards; ?&FE60=15:?&FE62=bank will set that bank for writing. Made it easy to write to it from anywhere, but it interfered with other user port usage. It's not relevant to your board at all. Don't do this if you have an MMC board plugged into your user port 'cos it can cause it to stop working.

As an aside, I have found this board to be flexible, easy to use, and a perfect partner for the beeb, so much so to this day I use my beeb way more than my master.

I like my 2M128 board, and even wrote my own manager ROM to replace the buggy one solidisk provided. Not that I really use the shadow modes it offers 'cos it slows things down and isn't really worth the effort with all the vector kludging that's needed.

BITD I would use a feature of the Soldisk DDFS to let me use the 2M128 memory as a 100K RAMdisk. When assembling code I could copy all the sources to RAM and then use the 65C02 assembler on that. So so much quicker than floppy Today I use beebasm on Linux and UPURSFS to get the results on the Beeb, so I don't really do this any more!

Statistics: Posted by sweh — Wed Jan 28, 2026 2:07 pm

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