Apple //e Microprocessor

[Vinci]

Hi Guys
i'm looking for a cgs65CE02 to my Apple //e, it is a Commodore version of 65c02, if anyone has one and wants to sell it, leave a message

[rpiguy2]

Vinci wrote:

Hi Guys
i'm looking for a cgs65CE02 to my Apple //e, it is a Commodore version of 65c02, if anyone has one and wants to sell it, leave a message

That chip was only ever used in the Commodore serial expander for the Amiga 2000. It will be exceedingly hard to find. Especially because it is a 16-bit chip with a full 16-bit stack mode, not just a clone of the 65c02. Therefore, collectors pretty much have bought all of these.

[Proxy]

honestly with the chances of finding someone who has one of those and is also willing to sell it (likely for a very very high price due to the rarity), it would probably be a lot cheaper and faster to learn hardware design and code up your own 65CE02 softcore for an FPGA.

[gfoot]

... and then see if you can sell them on eBay

[Dr Jefyll]

Vinci wrote:

i'm looking for a cgs65CE02 to my Apple //e

You want to put a 'CE02 in an Apple IIe? Isn't that rather a bold experiment? I'm not criticizing the idea, but it certainly provokes my curiosity!

According to Wikipedia, the orininal IIe comes with a plain, ol' 6502, while the Enhanced and Extended IIe's use a 65C02. The 'CE02 is (mostly?*) pin compatible, but the cycle counts for many of the instructions are different (ie, faster), which may present a problem for any code that's timing sensitive. Moreover, according to a link in this post by BigEd, the 'CE02 "has a bug in decimal mode: SBC doesn't quite work."

I might be able to help in your search . But maybe you could share your plans with us, please.

-- Jeff

*- the 'CE02 datasheet mentions DMA capability, which to me suggests the chip has a BE input. However, the pinout shown is identical to that for a 6502 -- ie, no BE pin.

[BigDumbDinosaur]

Dr Jefyll wrote:

The 'CE02 is (mostly?*) pin compatible, but the cycle counts for many of the instructions are different (ie, faster), which may present a problem for any code that's timing sensitive.

That would most likely be the disk subsystem, which, among other things, was dependent on the 6502’s bus behavior during intermediate (“dead”) cycles in an instruction. Recall that when Bill Mensch designed the 65C816 he got rid of dead cycle bus behavior. However, Apple's disk code depended on it, so the bus shenanigans had to stay.

Quote:

the 'CE02 datasheet mentions DMA capability, which to me suggests the chip has a BE input. However, the pinout shown is identical to that for a 6502 -- ie, no BE pin.

That was likely wishful thinking on CSG’s part. Aside from the non-existent BE, I don't see anything else in the device’s specs that would suggest any kind of DMA capability. In any case, Commodore had one foot in the grave by the time the CE02 made it off the drawing board. They had too much invested in the Amiga and the eight-bit crowd there was definitely suckling on the hind teat, budget-wise.

All that said, I fail to see any good reason for trying to adapt the 65CE02 to anything. Disregarding its value as a collector’s item (which for me would be approximately $0.00), it was very much an experimental MPU, complete with errata (as mentioned by Jeff). Other than some faster instructions (as well as new ones that replace previously-undocumented ones), I'm not seeing any benefit to adapting it to the IIe.

I’d think if you wanted to soup up your IIe, adapting the 65C816 to it would be more profitable. There’s a lot to be said for 16-bit capability, even with a system that natively can address a maximum of 64KB. However, that the 816 has no undocumented instructions may not bode well in the IIe, unless it was originally equipped with a 65C02.

[BigEd]

Welcome, Vinci! I hope you have success in your experiments. (As Jeff notes, what you propose is not totally straightforward.)

(Thanks, Jeff, for the link back to that earlier post: I've now repaired the links there.)