[CC-40] Need some assembly help

[+acadiel]

Hey all -

 

I am assisting the MESS team with getting proper dumps from the CC-40, so we can get a MESS emulation for it operational. We have dumped the eight existing carts (and verified those dumps with a second source who already had them), and have dumped the 2K on processor ROM. What remains is the 32K bank switched system ROM.

 

The CC-40 has 64K address space, much like the TI-99/4A. What's cool is that it exposes half of that space directly to the cartridge slot (>5000 to >CFFF). That cartridge slot also has a bank switch line, so you can get a 64K image in there.

 

Probably because of this design decision, that leaves 32K open for the rest of the memory map, including RAM (18K), system ROM (8K bank switched) and other (6K). So, the system ROM is bank switched in 8K increments, controlled by the routines in the 2K of processor ROM.

 

TI did add a nice "system ROM page select" in the built in debugger, CALL DEBUG. However, they protected it to where it does not actually bank switch (probably to prevent me from trying to do exactly what I'm doing).

 

So, here are my thoughts:

My only alternative (other than desoldering the ROM and sending it to someone) is to figure out which register controls the ROM bank switch, write a small assembly program in CALL DEBUG and execute it from the 18K CC-40 RAM, and copy the ROM in 8K segments to a 32K constant memory cartridge, then dump it from the cartridge space.

 

That should be the easiest way to do this without harming any hardware, but I need someone's help. This is where you assembly people come in who can help write a small bank and copy loop, probably not much different conceptually than the cartridge copy to 32K RAM deal we've been doing on the 4A. The difference here is that I'm entering in assembly hex pneumonics on CALL DEBUG and executing them.

 

Any volunteers? This is one of the last things we need for CC-40 emulation!

[+mizapf]

Is something useful in this file, possibly? I have not studied it yet, being quite long.

 

ftp://ftp.whtech.com/hexbus_cc40_ti74/cc40%20ti74%20hexbus.txt

[+acadiel]

Is something useful in this file, possibly? I have not studied it yet, being quite long.

 

ftp://ftp.whtech.com/hexbus_cc40_ti74/cc40%20ti74%20hexbus.txt

 

Yep, I got my memory map from there (and the user manual). I've been through just about that whole document.

[+acadiel]

Bump :-)