exxos's Atari, Amiga & retro forum

cmorley wrote: 12 Aug 2022 10:47 All normal.

Your combined MMFS+BASIC ROM is a 32KB 27C256 with 2 images in - the standard sockets on a B only address 16KB hence my adapters.

Ok, that makes perfect sense.

cmorley wrote: 12 Aug 2022 10:47 The Acorn MOS checks the ROMs from 15->0. It starts the first "language" ROM it finds. Right most socket is 15 (and 3,7,11).

Ok, so with Interword removed, I have MMFS at slot 15 and Basic at slot 11.

cmorley wrote: 12 Aug 2022 10:47 The "language" can use additional memory workspaces so any ROM that runs a front end is usually a "language" so word processors or PCB software etc usually have a language entry point.

Ok, so It seems that whatever slot I put Interword in, it shows up in slot above BASIC in slot 11. I suppose I could dump the MMFS ROM and reburn so BASIC appears ahead of MMFS.

The Interword ROM is on a daughterboard with some sort of IC (GAL/PAL maybe) and won't work off it. It always appears high up, and in fact shows in multiple slots when using RTOOL.

I can drop out of Interword by using the :kill command to drop to the * prompt, then typing BASIC, or I can press SHIFT+BREAK to force a boot from the disk inserted into the MMFS disk 0.

I'd really like to keep Interword as it came with the machine and has some sentimental value, but unless I use the original mask ROM, it seems to become the language ROM with the highest priority.

Any suggestions welcomed :)

As the OS scans the ROMs any without extra decoding will appear 4x... once for 15-12 and 3 ghost/alias images. It checks the first 1K against the other ROMs and if that is identical it assumes the ROM in the logical bank is a duplicate so marks it as NFG in the ROM table.

What you need is BASIC in 15 and interword in any other socket.

Best options:

• put the SWRAM/ROM in the right most slot and burn a new 27C256 with BASIC in 4000-7fff and MMFS in 0-3fff.
• put the EEPROM in the right most slot and program BASIC in to bank 15

If you want to burn MMFS then get the latest version here https://github.com/hoglet67/MMFS/releases

There are a few ROMs with PAL/GAL bank switching from BITD. The INTER products and some spellchecker and Watford Quest Paint spring to mind. There are some reverse engineered PAL JED files on stardot IIRC.

cmorley wrote: 12 Aug 2022 12:20 As the OS scans the ROMs any without extra decoding will appear 4x... once for 15-12 and 3 ghost/alias images. It checks the first 1K against the other ROMs and if that is identical it assumes the ROM in the logical bank is a duplicate so marks it as NFG in the ROM table.

What you need is BASIC in 15 and interword in any other socket.

Best options:

• put the SWRAM/ROM in the right most slot and burn a new 27C256 with BASIC in 4000-7fff and MMFS in 0-3fff.
• put the EEPROM in the right most slot and program BASIC in to bank 15

If you want to burn MMFS then get the latest version here https://github.com/hoglet67/MMFS/releases

There are a few ROMs with PAL/GAL bank switching from BITD. The INTER products and some spellchecker and Watford Quest Paint spring to mind. There are some reverse engineered PAL JED files on stardot IIRC.

That's great, thanks for the info I'll reburn the ROMs as suggested to get BASIC into slot 15.

I'll let you know how it goes.

cmorley wrote: 12 Aug 2022 12:20
Best options:

• put the SWRAM/ROM in the right most slot and burn a new 27C256 with BASIC in 4000-7fff and MMFS in 0-3fff.
• put the EEPROM in the right most slot and program BASIC in to bank 15

I did exactly as above and it worked first time. BASIC and MMFS have switched places, with BASIC now in slot 15 & MMFS in slot 12, so no more booting straight to Interword and everything else in the slots provided by your EEPROM all work very much as expected.

So I now have a free ROM slot, any suggestions on what I might put in there?

rubber_jonnie wrote: 13 Aug 2022 16:16 So I now have a free ROM slot, any suggestions on what I might put in there?

ZIF socket on a fly lead to the ashtray hole? Or save it for something later.

cmorley wrote: 19 Aug 2022 12:07

rubber_jonnie wrote: 13 Aug 2022 16:16 So I now have a free ROM slot, any suggestions on what I might put in there?

ZIF socket on a fly lead to the ashtray hole? Or save it for something later.

Ooooh, I like the ZIF socket idea, might have to look into that, thanks.

Any recommendations on the ZIF socket, is there a particular one that fits best?

Just a 3M TEXTOOL one (or chinese copy) is fine. I have a Watford Electronics one from BITD - google it you will see the PCB & the way they did it. Others were made too. I think it has some pull ups on the address bus and decoupling otherwise it is just a passive extender.

You can wire up A14 and A15 from IC76 to support 27C512 in the ZIF socket very easily - solderlessly if you use clips.

cmorley wrote: 19 Aug 2022 17:13 Just a 3M TEXTOOL one (or chinese copy) is fine. I have a Watford Electronics one from BITD - google it you will see the PCB & the way they did it. Others were made too. I think it has some pull ups on the address bus and decoupling otherwise it is just a passive extender.

You can wire up A14 and A15 from IC76 to support 27C512 in the ZIF socket very easily - solderlessly if you use clips.

Thats good stuff, thank you for all the useful info :)

So I have been trying to get the dual Cumana drive that came with the Beeb working.

Cosmetically it is in really good order, and obviously came from a clean home as it was dust free internally, but there is a problem with the 2nd drive :(

Testing with the working drive, as you insert a floppy disk, the write protect sensor detects the incoming disk and spins the motor. When you insert a disk in the failed drive, it simply makes a very quiet buzz and the motor doesn't spin. Sometimes you can see it try ever so slightly though.

Having checked power and all the signals against the working drive, I know the write protect sensor is working, and the signal from the logic board is present at the motor board, and the motor is trying to run, so I suspect a problem on the motor board.

Main problem now is actually being able to remove the motor board, the spindle is really tightly attached and I need to get topside to see what the possible failed components are.

Although the voltages do measure OK though, I'm thinking perhaps I should try an external PSU just in case, you never know...

I need to find an image of the Cumana disk too, as whilst the good drive reads the disk, it seems to be empty, and I need the formatting utilities.

Which mechanism is in the drive enclosure? One of them with the thin latch (TEC maybe) is notorious for bad caps on the control board leaking. TEAC and Mitsubishi mechanisms are better.