Running 68020 software on 68000 ? 020 emu control panel?

Anything not about Mac emulation.

Moderators: Cat_7, Ronald P. Regensburg

Post Reply
User avatar
that-ben
Granny Smith
Posts: 141
Joined: Tue Nov 10, 2015 7:50 pm

Running 68020 software on 68000 ? 020 emu control panel?

Post by that-ben »

Hello all OLD members! Today I have a question that is kind of off topic, but targets 68K experts out there that are still alive! :O (just kidding)

Is there a way to bypass and/or emulate some of the 68020 functionality under a 68000 system? Namely, say I have a Mac Plus running System 7.5 and I'd like to launch a RealBasic app on it, but I'm facing a "Coprocessor not installed" crash. After digging on ARCHIVE.ORG I found a 20 years old page that mentioned 68K compiled RealBasic apps all require at the very least a 68020 CPU because RB apps run inside a CFM-68K runtime environment, which in turn require a 68020 CPU to install in RAM on boot, therefore RB apps also require a 68020 CPU, even if they are launched under System 7.5. The same app binary launches and executes no problem under System 7.5 with a Macintosh II ROM, but not with a Mac Plus ROM.

Is the only solution hardware based, such as buying and installing a 030 accelerator card like this: https://www.micromac.com/products/performer.html

...Or is there some patch I could apply on RB apps or in the System to fake 020 or 030 to bypass CFM-68K runtime environment requirements? Can CFM-68K be patched to run on 68000?

Thanks!
User avatar
adespoton
Forum All-Star
Posts: 4208
Joined: Fri Nov 27, 2009 5:11 am
Location: Emaculation.com
Contact:

Re: Running 68020 software on 68000 ? 020 emu control panel?

Post by adespoton »

CFM-68k is not compatible AFAIK. The instructions the software is using were implemented for 68020 processors and later to provide external library support via ObjectSupportLib, which uses CFM-68k to load it. So from the compiler side, you've got a toolchain targeted all the way from RB through to the 020 computer that's using a technology not available on the 68000. I have heard of no virtualization/emulation of either CFM or the 020 chip for older 68000 processors. In fact, most of the features of CFM are only available on the 68030 and later. If you can re-point RB to use Apple Shared Library Manager instead of CFM-68k/ObjectSupportLib, you *may* be able to get it to work, as I think that kind of shared libraries are supported by the 7.5/68000 combo.

And this is something I ran into back in the 90s, as I wrote stuff on a 68030 Mac using RB, and found that it wouldn't run on a Mac Plus running 7.5.3.
User avatar
that-ben
Granny Smith
Posts: 141
Joined: Tue Nov 10, 2015 7:50 pm

Re: Running 68020 software on 68000 ? 020 emu control panel?

Post by that-ben »

adespoton wrote: Tue Jan 05, 2021 7:51 pm CFM-68k is not compatible AFAIK. The instructions the software is using were implemented for 68020 processors and later
Yes, I've read about this for over 2 hours now, so it is now clear that the only way the Plus is going to run RB apps (even the ones compiled with as far as back as the pre-1.x alpha releases) will be thru a hardware 030 accelerator card (or 020 but... if I upgrade, I'll upgrade all the way). I'm so not ready to fork out hundreds of dollars on an accelerator card tough. This is a shame, I should have got a Mac SE/30 instead, it was so much more advanced compared to the Plus, with only like 1 year difference at some point in its market lifespan.

Those 49$ PFPL16 030 accelerator cards from MicroMac back in the late 90's tough, HMMMM I should have got a hundred of those back then, DAMN.

Thanks, I guess this topic is closed :(
User avatar
that-ben
Granny Smith
Posts: 141
Joined: Tue Nov 10, 2015 7:50 pm

Re: Running 68020 software on 68000 ? 020 emu control panel?

Post by that-ben »

Well, in just 2 days, I self taught THINK Pascal 4 using small examples found here and there on the internet and some very nice technical bits from the 1990 and 1991 Macintosh programming manuals which are scanned as PDF and are for the most part searchable. The Pascal syntax is weird, but it's not the end of the world and I'm already at the stage of having off-screen to on-screen graphics copying (for making smooth animations without screen glitching/tearing/flashing) and I found out Pascal is actually quite fast even on a 8mhz 68K ! I can fill the screen with a pattern and draw 1000 random 16x16 objects every second! Tough, with the game logic, performance will probably go down by a lot. We'll see. I'm now getting comfortable with it after 2 days and it's actually pretty fun to program and see B&W pixels animating on a 35 years old Mac :P

Now remember that Color QuickDraw was not available yet, so there is no fancy fading, transparency masks and what not. This is all just straight 1-bit bitmaps. SO SIMPLE, yet mind boggling how they could achieve 3D modeling even 5 years BEFORE that using even more primitive IDE's. It's fascinating.
Post Reply