MiSTer FPGA Forum

Anyone know if someone is actively working on a Commodore 128 core for the MiSTer?

Probably not because it would be quite complicated thing. 2 different CPU's, 2 totally different display outputs, three working modes...

Although I would love to see one, I had c128 as my first computer when I was kid.

Goingdown wrote: ↑Wed May 27, 2020 2:28 pm Probably not because it would be quite complicated thing. 2 different CPU's, 2 totally different display outputs, three working modes...

Although I would love to see one, I had c128 as my first computer when I was kid.

Same here!

I for one would love to have a C128 core because I've never really had the chance to play with one.
I don't think that it'd be too difficult, I think it's more that the current core devs are concentrating on the cores they'd actually like to use instead.

It's all down to personal choice. If I were a FPGA dev, I'd have it near the top of my list (after Dragon32) but alas I'm not so I'll just stick to using the awesome cores that people have already written.

I did look at FPGA development but it appears that I'm simply not clever enough to do so

The problem with the 128 is there's very little software specifically for it, having owned one physically way back when I can honestly say it spent almost all of it's life in 64 mode and taking up far too much desk space.

The Z80 is for CPM software, which was already dead by the time the 128 came out .. and there are better faster places to run that software, although I'm not sure why anyone would.

Super CPU and ram expansion support for the C64 core would put a lot more content on the table.

Coffea wrote: ↑Thu May 28, 2020 9:00 pm Super CPU and ram expansion support for the C64 core would put a lot more content on the table.

I agree, other than 1571 and 1581 hardware implementing too

lot of stuffs are already (almost) done, cpu, z80, vic chip. no need to start with a complete c128 core, maybe a basic core with 128k vic z80+6510 cpu and sid, then other functionalities added over time (vdc, 2mhz vic + cpu) and so on.
there is very little software for the c128? yes, maybe, but surely there is more software for the C128 than the only one title for the c64 SCPU

I would also like a c128 core

what about a C65 core?

Televicious wrote: ↑Sat May 30, 2020 9:36 pm what about a C65 core?

https://github.com/MEGA65/mega65-core

Chol wrote: ↑Sun May 31, 2020 10:12 am

Televicious wrote: ↑Sat May 30, 2020 9:36 pm what about a C65 core?

https://github.com/MEGA65/mega65-core

While the c65 would be neat, there was zero commercial software made for it and nearly no homebrew software, just a couple simple demos, the c65 mega folks are making their own "re-imagined interpetation" of the machine since the actual machine, filling in the missing gaps, etc.. the real machine was never finalized (and even with real c65 machines there is a lot of incompatibility between the few surviving prototypes) .. so this would really be a "fantasy" interpretation .. like the X16 Commander ..

ericgus09 wrote: ↑Mon Jun 01, 2020 5:47 am While the c65 would be neat, there was zero commercial software made for it and nearly no homebrew software, just a couple simple demos, the c65 mega folks are making their own "re-imagined interpetation" of the machine since the actual machine, filling in the missing gaps, etc.. the real machine was never finalized (and even with real c65 machines there is a lot of incompatibility between the few surviving prototypes) .. so this would really be a "fantasy" interpretation .. like the X16 Commander ..

True, the mega65 project is fascinating to follow and they go premium with the hardware, thus it is promising to be a beautiful 8bit machine.

The core may be interesting in a couple of years if and when the homebrew scene takes off on the mega65, but for now there is nothing readily available. The mega65 core may be further developed by then, too.

Goingdown wrote: ↑Wed May 27, 2020 2:28 pm Probably not because it would be quite complicated thing. 2 different CPU's, 2 totally different display outputs, three working modes...

Although I would love to see one, I had c128 as my first computer when I was kid.

It's not THAT different. The CPUs don't run at the same time, and the Z80 is dead stock. The MSX core and ZX core both have good Z80 implementations.

The 8502 is a slightly different chip than the 6510 used in the C64, but the differences are well known and shouldn't be challenging. The VIC chip has some differences as well, to support the extra keyboard pins and to handle the clock divider (allowing the CPU to run at 2MHz, rather than 1MHz.)

I believe the only whole, new chip is the MMU... but that's well enough known that it should be possible to implement a new one to the same specification.

tomxp411 wrote: ↑Fri Jul 17, 2020 5:00 am

Goingdown wrote: ↑Wed May 27, 2020 2:28 pm Probably not because it would be quite complicated thing. 2 different CPU's, 2 totally different display outputs, three working modes...

Although I would love to see one, I had c128 as my first computer when I was kid.

It's not THAT different. The CPUs don't run at the same time, and the Z80 is dead stock. The MSX core and ZX core both have good Z80 implementations.

The 8502 is a slightly different chip than the 6510 used in the C64, but the differences are well known and shouldn't be challenging. The VIC chip has some differences as well, to support the extra keyboard pins and to handle the clock divider (allowing the CPU to run at 2MHz, rather than 1MHz.)

I believe the only whole, new chip is the MMU... but that's well enough known that it should be possible to implement a new one to the same specification.

no one will stop you from implementing this.

tomxp411 wrote: ↑Fri Jul 17, 2020 5:00 am

Goingdown wrote: ↑Wed May 27, 2020 2:28 pm Probably not because it would be quite complicated thing. 2 different CPU's, 2 totally different display outputs, three working modes...

Although I would love to see one, I had c128 as my first computer when I was kid.

It's not THAT different. The CPUs don't run at the same time, and the Z80 is dead stock. The MSX core and ZX core both have good Z80 implementations.

The 8502 is a slightly different chip than the 6510 used in the C64, but the differences are well known and shouldn't be challenging. The VIC chip has some differences as well, to support the extra keyboard pins and to handle the clock divider (allowing the CPU to run at 2MHz, rather than 1MHz.)

I believe the only whole, new chip is the MMU... but that's well enough known that it should be possible to implement a new one to the same specification.

With respect, this is actually just flat wrong.

The CPUs *absolutely* run at the same time, and a few demos and applications have been written to exploit this.

Bus arbitration for the Z80 is _ridiculously_ complicated because of the way they had to shoehorn it in, so while the chip implementation itself may be readily available, integration is *not* trivial.

The VDC is one of the least-understood graphics implementations ever built, despite its relative architectural simplicity. The fact that it more or less runs on cycle waits makes timing absolutely critical, and that's the single most challenging thing to get right with FPGA.

Sorgelig wrote: ↑Fri Jul 17, 2020 5:53 am

tomxp411 wrote: ↑Fri Jul 17, 2020 5:00 am

Goingdown wrote: ↑Wed May 27, 2020 2:28 pm Probably not because it would be quite complicated thing. 2 different CPU's, 2 totally different display outputs, three working modes...

Although I would love to see one, I had c128 as my first computer when I was kid.

It's not THAT different. The CPUs don't run at the same time, and the Z80 is dead stock. The MSX core and ZX core both have good Z80 implementations.

The 8502 is a slightly different chip than the 6510 used in the C64, but the differences are well known and shouldn't be challenging. The VIC chip has some differences as well, to support the extra keyboard pins and to handle the clock divider (allowing the CPU to run at 2MHz, rather than 1MHz.)

I believe the only whole, new chip is the MMU... but that's well enough known that it should be possible to implement a new one to the same specification.

no one will stop you from implementing this.

Heh, no. If I did tackle a system, it would be to build the Altair 8800 into something actually usable.

https://c128.se/posts/silicon-adventures/
someone has decapped the C128 CPU
one step closer

Wow. I have no clue about what's going on there and yet it was a fascinating read. Humans can be devilishly clever: first designing something as insanely complex as a microchip and then being able to reverse engineer it from scratch.

He is doing the C128 MMU next.

Some more discussion on the PLA here:
https://news.ycombinator.com/item?id=24004640

Impressive work.

Reading the Gihub for the C64 core, I see newly implemented C128 being mentioned.


Features: C128/Smart Turbo mode up to 4x.

Turbo modes:
C128 mode: this is C128 compatible turbo mode available in C64 mode on Commodore 128 and can be controlled from software, so games written with this turbo mode support will take advantage of this.

Smart mode: In this mode any access to disk will disable turbo mode for short time enough to finish disk operations, thus you will have turbo mode without loosing disk operations.

So is the C64 core now also a C128, implement SOME features (playing C128 software), or am I just overly excited to see '128' on screen'?

It allows for 2MHz operation on the C64 - that's it.

Yeah, a C128 core would be nice. The C128 was my second computer, after the C64 so it would be mainly for nostalgia as I used my 128 mostly in 64 mode. I suspect that it’s the case for most 128 users so there’s no strong incentive to develop the core. But the 128 had a couple of good features like a much enhanced BASIC and 80 column display. Geos 128 was also a strong point. I regret having sold my 128 and I miss it more than my 64.

I would be ready to make a small donation to have this core. If enough of us can do the same, maybe a dev could be interested to start working on it.

@Lodovik It might be worth you taking a look at BMC64 - its Commodore 128 support is excellent.

I would love a C-128 core as well. I wouldn't need the CP/M side of it (never used it on the real machine), but really loved CBM BASIC 7.

It would be neat to have the RAM Banks available (the 1750 at least…you can never have enough memory you know.)

I wonder if the PEN command and a real light pen could work with the CRT? Maybe GO64 could automatically start up a separate C-64 core even if it couldn't be included in the 128 core…

Yes !! It would be wonderful !!

A fully functional C128 would be the grand finale of 8-bit home computers, but it's a complicated beast so I'm not holding my breath.

tomxp411 wrote: ↑Fri Jul 17, 2020 5:02 pm

Sorgelig wrote: ↑Fri Jul 17, 2020 5:53 am

tomxp411 wrote: ↑Fri Jul 17, 2020 5:00 am

It's not THAT different. The CPUs don't run at the same time, and the Z80 is dead stock. The MSX core and ZX core both have good Z80 implementations.

The 8502 is a slightly different chip than the 6510 used in the C64, but the differences are well known and shouldn't be challenging. The VIC chip has some differences as well, to support the extra keyboard pins and to handle the clock divider (allowing the CPU to run at 2MHz, rather than 1MHz.)

I believe the only whole, new chip is the MMU... but that's well enough known that it should be possible to implement a new one to the same specification.

no one will stop you from implementing this.

Heh, no. If I did tackle a system, it would be to build the Altair 8800 into something actually usable.

That would be nice!

Lodovik wrote: ↑Tue May 18, 2021 12:15 am Yeah, a C128 core would be nice. The C128 was my second computer, after the C64 so it would be mainly for nostalgia as I used my 128 mostly in 64 mode. I suspect that it’s the case for most 128 users so there’s no strong incentive to develop the core. But the 128 had a couple of good features like a much enhanced BASIC and 80 column display. Geos 128 was also a strong point. I regret having sold my 128 and I miss it more than my 64.

I would be ready to make a small donation to have this core. If enough of us can do the same, maybe a dev could be interested to start working on it.

Hello,

I would also be willing to support such a project

Me as well,
And despite Sorg is right by saying that in case of the C128 core will be there, the 1st command that most of the people will type will be GO64, for me it won't be the case, the C128 has the CP/M, some nice utilities and some dedicated games that I'd like to see on the Mister. And as Bas said above, it would be the grand final of 8 Bit computers and will close the existing gap in the Commodore cores.

C128 would be very nice, but for me definitely not a "grand finale". Many 8-bit cores still lack some important functionality, eg: write to floppy in Apple II (as per this thread: viewtopic.php?f=29&t=2859).