CUDA, EGRET, HC6805 Hacking

[techknight]

Dont know if it still works or not. 

 

[Bunsen]

It works.

 

[powermax]

It works.

Glad to know, thanks!

IIUC, I'd need an extra account to access the Wiki, right?

Is there any ASIC-related Wiki section there? I didn't see any. Where may I post such information to?

 

[pb3623]

I'll throw this out there even though I'm not 100% positive it's still relevant:

I would be willing to at least loan out my nonfunctional Q700 board (the one that spawned this thread) or would outright donate it to science to help further this cause. It's not doing anything for me right now and may never work. It (and I!) would benefit if there's even a hint of what caused the ADB issue I'm having. PM me if there is any interest.

 

[Dandu]

Is this possible tu dump and recreate a CUDA Lite chip ?

It would be fun to add PS/2 Mouse and Keyboard on a Mac.

I thunk it's the same chip, but with more memory and code inside the firmware to handle PS/2 peripherals.

On the Mac side, the Power Mac 4400 use this chip, but without the component to use PS/2 (the trace are on the motherboard)

 

[powermax]

Is this possible tu dump and recreate a CUDA Lite chip ?

Never heard anything about it. Can you supply some more information on that CUDA Lite chip?

I thunk it's the same chip, but with more memory and code inside the firmware to handle PS/2 peripherals.

Well, CUDA as well as its predecessors (Bit-bang, Egret) is basically a multipurpose MCU that emulates some peripheral bus protocol using the bit banging approach. In other words, all required functionality is implemented in software.

To recreate the chip, we thus need to download and understand its firmware.

IIRC, Arbee from MAME project may have already obtained a dump of CUDA Lite as he did for other CUDA versions. I'm going to ask him...

 

[Dandu]

I have found the information into the LPX-040 motherboard developer note : https://web.archive.org/web/20030410054223/http://developer.apple.com/techpubs/hardware/Developer_Notes/Macintosh_CPUs-PPC_Desktop/LPX-40_Dev_Note.pdf

The Cudla Lite is on the clone logic board and on Power Mac 4400. It's like a CUDA classic chip with PS/2 support.

On the clone from Motorola, there is PS/2 port, on the Power Mac 4400, there is trace on the logic board only.

 

[powermax]

Hi crews,

I've just started uploading a commented assembly for the Cuda Firmware v2.37, see this Github repository. To my knowledge, that's the latest firmware available but we need to re-check it. In the next days, I'm going to put even more docs on Cuda - so stay tuned!

 

[trag]

Thank you, Powermax.

 

[bigmessowires]

Thanks for the commented disassembly! Is that the whole thing, or just a part? I didn't see anything in there for how CUDA monitors the power button and asserts or de-asserts /PFW to turn on/off the power supply.

 

[jdlanza]

Is this project still active?

 

[LaPorta]

Did anyone ever get anywhere with making a replacement EGRET? I need one yesterday!

 

[joshc]

Did anyone manage to dump the contents of an Egret? My understanding is that it's got custom Apple ROM contents to handle RTC/ADB.

My understanding of how most of this works is limited beyond "there's stuff on a chip there and we want to grab that and program a replacement chip", so what are the main blockers to achieiving this?

 

[demik]

Did anyone manage to dump the contents of an Egret? My understanding is that it's got custom Apple ROM contents to handle RTC/ADB.

There is a dump tool and a few dumps around. AFAIK no-one build a replacement (yet).
Dump tool: https://www.gryphel.com/c/minivmac/extras/egretrom/
Dumps: https://www.buriedbits.org/a-whole-lotta-roms

 

[joshc]

So how would we go about doing something with those ROM dumps?

Tekmos seem to make a range of microcontrollers that are the modern day equivalent of the Motorola ones... https://www.tekmos.com/68hc705-microcontrollers/tk68hc05b6-microcontroller

No idea if that's viable or not though.