The C128 and Z80 CPU ...or Intel 8088?

[Iggy]

I believe a C65 would have been better.

Obviously.
I never really got the idea of including the Z-80 either.
CP/M was pretty dated and lacked graphics support.
So what was the point?

[Iggy]

CP/M 3.0 was only 2 years old when the 128 came out and there was a huge library of software available for it including business and productivity software that was seriously lacking on the C64.

All of it text based with no graphics or sound.
Still a step backwards.

[Iggy]

Oh yes, I'm not trying to stir up any which OS is better argument - I was just thinking of what if the 8088 was used instead and what different path MAY have unfolded - had they perhaps made the C128 into some PC compatible too.

I remember seeing the DEC Rainbow and thinking it was cool as well.

Glad to meet someone else that remembers that system.
It was pretty cool, but really expensive for a PC clone.
Also had the first AND processor I had ever seen inside.

[Iggy]

It would have been impossible to make it PC compatible. Using the 8088 would also not have solved the issue why the Z80 was put in there to start with. In most of Bil's videos he says it was because the CP/M cartridge exceeded the amp budget and the decision to start the Z80 first instead of the 6502, to fix magic voice autostart, came later.

Bil learnt what C64 compatibility meant when they built the C128. IBM learnt what PC compatibility meant when they built the IBM PCjr. A C128 with an 8088 would have been less compatible than the PCjr, which itself was a failure.

PC compatibility never helped the Amiga either.

CP/M was more suited because of hardware fragmentation, each manufacturer made hardware to their own design and so applications had to go through the OS. While there was some fragmentation in the MS-DOS market to start with (Chuck Peddles Victor/Sirrius for example) by 1985 the market demanded that every piece of CGA/DMA/floppy/hard disk/sound hitting software would work.

An NEC V20 on the other hand would have allowed CPM-80 and CPM-86 applications to run & we could even have seen a port of GEM rather than GEOS.

Impossible? Nonsense.
My firm made the PT68K4 PC compatible with a V20 based board.
The Amiga could be made PC compatible with a series of boards that topped out with a '386 based board (and those have a much better resale value than PCs based on the same processors).
Of course a system could have been built with both PC and C64 compatibility.

And the PCjr's video modes lived on in the Tandy 1000 series.
So that machine did have some significance.

GEOS and GEM? Almost as ugly a solution as CP/M.
MS-DOS and Windows compatibility have far more utility.

Most of your post appears to be unsupported opinion, unless I am reading it wrong.

[Iggy]

CBM did make the desktops, like the Commodore Colt, PC-10, PC-20, PC-30, (and more), and 286, 386, and 486 laptops.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm

So if you consider those projects, wouldn't a C64 expansion card have made sense?

[Iggy]

A cheaper 8088 or 8086 processor would have provided CP/M-86 compatibility, and MP/M-86 compatibility with a possible upgrade to Concurrent DOS if CGA/VGA compatibility was implemented via a VLSI.
When the C128 was in its planning stages custom chips were becoming quite common.
While the earlier chips in the C64 and Amiga required a large investment to create, the latter custom chips in devices like the Tandy 1000 and the Color Computer 3 were significantly less costly.
AND as Commodore owned MOS...the C128 wasn't a particularly adventurous design (and for that matter Bill wasn't that great a designer).

[Iggy]

In 1985 you would need register level CGA/floppy/dma/irq/serial etc. You couldn't reuse anything from the C64, so it would essentially be a PC and a C64 in the same box (like https://en.wikipedia.org/wiki/Amstrad_Mega_PC).

The Amiga at least could display the video from a PC using it's graphics chip, so a combined hardware and software approach allowed it to work. But to make it compatible with games you had to use an actual ISA graphics card. So it was just an Amiga and PC in the same box, it didn't really save any money and you could get better PC's.

Sure you could stick an 8088 in the C128 and it would have access to 64k at a time. No software would know how to display anything on the screen or access more than 64k. The original PC came with 64k so you could run software that worked on that as long as it only used BIOS and DOS calls to access hardware (which a lot of software didn't).

The Z80 came quite late in the C128 design, so there was never a time when it would have made sense to design something radically different with an 8088 that allowed more than 64k at a time.

Of course everything is possible given enough time and money, but keeping to the C128 selling price and spending very little in chip design and it was impossible.

Ah! My apologies. You guys are frequently good for some education.

"The Z80 came quite late in the C128 design..."

That explains SO much.
I've always blamed Bill for the kludged together nature of the C128.
Its like they tacked a cheap CP/M board onto an existing design, which appears to be what happened.
I'd always thought that was what Bill intended at the outset.
Which should explain my bad attitude about him.
He and Dave must have felt a constant sense of butt hurt dealing with Commodore's management and their perpetual penny pinching.

They probably should have just left the Z-80 out (or the 6502).
If you compare the C128 to something like an MSX system, the C128's implementation of the Z-80 processor comes off looking really lame.

[Iggy]

I am not sure I would not have favored a 2MHz 6509 with no Z-80.
Faster operation just makes sense.

For that matter, if you eschew compatibility,  Commodore could have used a 2MHz 6809 which has a lot of advantages over a 6502 based CPU.

One of my primary reasons for favoring the Amiga is that system's use of a decent Motorola processor.
I have never been that impressed with MOS' cut rate offerings.