What does the inside of a REU look like to C128 software?

[commodorejohn]

Yeah, it does require a second MMU (although it gives the name of a company which still sells them, so you don't necessarily have to cannibalize one from a 128,) and it takes some doing, but it is possible.

[airship]

Twin Cities 128 also  published a pair of articles (issues #30 and #31) on expanding the internal RAM of the C128 to 256k and beyond. I've scanned it and uploaded it here. It comes complete with very nice GeoPaint renderings of the component layouts and wiring!

Here's a sample (reduced by 50%):

[RobertB]

Twin Cities 128 also  published a pair of articles (issues #30 and #31) on expanding the internal RAM of the C128 to 256k and beyond.

I've always thought that the idea of expanding the C128's memory to be interesting (Raymond Day has done it).  However, what program would make use of that expanded memory?

On the road, now in Grants Pass, Oregon,
Robert Bernardo
Fresno Commodore User Group
http://videocam.net.au/fcug
The Other Group of Amigoids
http://www.calweb.com/~rabel1/

[airship]

It adds banks, so you can use the BANK command to access it for whatever use you want. Good for ML, screens, multitasking, just about anything. It works with the REU, too. I think there's even a patch to make STASH, SWAP, and FETCH work with it.

[RobertB]

It adds banks, so you can use the BANK command to access it for whatever use you want. Good for ML, screens, multitasking, just about anything. It works with the REU, too. I think there's even a patch to make STASH, SWAP, and FETCH work with it.

Which begs the question, "Which programs work with it?"

             Now in Stockton, California,
             Robert Bernardo
             Fresno Commodore User Group
             http://videocam.net.au/fcug
             The Other Group of Amigoids
             http://www.calweb.com/~rabel1/

[airship]

LOL! 

I guess I have to do ALL the work for you Robert!

(1) Any program you write yourself, either BASIC 7.0 or M/L, which is specifically designed to make use of the new BANKs.
(2) Any commercial or PD program that does the same. Many make use of the REUs, and I suppose if they take the FETCH/SWAP/STASH route they can possilby be aware (or be made aware) of the extra RAM, but I don't know that for sure.
(3) If there is a utility, or if someone writes a utility, to make the use of this extra RAM relatively transparent to other programs, then compatible software would be able to use it.

I know that's not specific, but as I don't (a) have expanded RAM, or (b) lots of software to test with it, that's the best I can do for now.

If you RTFA, you'll see some BASIC and M/L demo programs that load pictures into the various banks, and move memory chunks from bank to bank. There's even a list of changes (only 7 BASIC lines!) to make the 'pound' animation demo for the REU run in these banks instead.

[RobertB]

I know that's not specific...

I remember when I asked Raymond Day about what he ran on his expanded-memory C128.  He smiled but gave no definitive answer.  In other words, it was an exercise in expanding the memory but other than that...

            Back in California,
            Robert Bernardo
            Fresno Commodore User Group
            http://videocam.net.au/fcug
            The Other Group of Amigoids
            http://www.calweb.com/~rabel1/

[airship]

     I remember when I asked Raymond Day about what he ran on his expanded-memory C128.  He smiled but gave no definitive answer.  In other words, it was an exercise in expanding the memory but other than that...

Yes, but just because something hasn't been used doesn't mean it isn't useful. It's the old chicken-and-egg thing. Nobody has expanded RAM, so no one ever wrote any software for it. And the guys who do expand their C128s are mostly hardware guys. The only software they're interested in is what it takes to get the hardware up and running.

A perfect example is the RAMBoard. It was a commercial product, but as far as I know only one (maybe a couple) disk copy program made use of it. Why? Because the market was too small (and they were almost all pirates). Even though the right software could have turned a 1541 or 1571 into a stand-alone coprocessor.

[RobertB]

It's the old chicken-and-egg thing. Nobody has expanded RAM, so no one ever wrote any software for it.

Yup.

A perfect example is the RAMBoard. It was a commercial product, but as far as I know only one (maybe a couple) disk copy program made use of it.

I only know of the RAMBoard utility that came with it.

             Truly,
             Robert Bernardo
             Fresno Commodore User Group
             http://videocam.net.au/fcug

[hydrophilic]

The MMU doesn't have output lines for additional RAM banks.  As you can see from the diagram, a 2nd MMU is needed (a little hard to get maybe) and it must be addressed seperately as can be seen from the decode lines, although I can't tell what address it maps to from the image.

Anyway, it would not work with BANK, STASH, etc. unless you modified the ROMs to access the 2nd MMU.  Cross-bank operations would become slower too (need to fiddle 2 register sets).

Off-topic, the GEOS image reminds me of something I noticed today while processing invoices.  It's not uncommon to get stock forms filled out with dot-matrix printers.  But I noticed several today that looked like they were filled out with GEOS, specificaly the California font.  ...I guess it could be a low-end PC printer using MS Sans Serif...