Question about the 144k Dev Cart

[X5900]

After successfully getting the A7800 DevOS 0.2 to run with my 48k Dev Cart, I've built the 144k Bankswitching Dev Cart (128k+32k SRAM), following the instructions provided by the included PDF (by Graham.J.Percy).

There's, however, a problem. It only partly works as expected ... If I transfer a 16k binary file to the Dev Cart, i.e. Centipede, it works for a while and crashes after about 5 minutes. If I try to upload a larger binary, anything above 16k, I only get a black screen. I've double checked all steps, again and again, and I can't find the fault, no solder bridges either, all continuity test check out. The instructions are mostly clear to me, with minor exceptions. In step #20 for example, it says "Jumper U1 pin 31(A14) to U1 hole 27(A14-BS).". The pinout for 128kx8 SRAMs says that pin 31 is actually A15, not A14. May that be the cause that it's not working?

 

It would help if someone could post some higher resolution pictures of such a card, maybe I've misunderstood one of the connections.

Edited October 23, 2016 by X5900

[+Mitch]

Which version of the upload software are you using? It has been a long time since I have used it but I think it needs a special version for the 144k cart.

 

Mitch

[X5900]

Good question, it's the one that came with DevOS 0.2, the file is from 2001 an the front end I've found is "Run7800.exe".

[X5900]

It doesn't have a version number, but in the upper right corner it says July 2000. I believe there's a newer version from 2002, but I couldn't find it anywhere.

[alex_79]

Try the one in this post:

http://atariage.com/forums/topic/159159-interesting-devos-cartridge-dumping-issue/page-2?do=findComment&comment=1958565

That's the command line program, I don't know if it will work with the "Run7800" frontend.

[X5900]

Great, thanks! I've tried the newer 78CTRL38.exe and to my surprise. it works! This was driving my mad, I've checked and re-checked all connections to the point where I was suspecting a faulty SRAM.

 

One thing however, I've tested it with 128k and 144k binaries, Alien Brigade (144k) worked, Ace of Aces (128k) started but crashed in the first mission, Dark Chambers (128k) only came up with a black screen. A 48k version of Galaga worked also.

 

Do I have to set some extra switches during upload?

[X5900]

I did a bit more testing with the newer 78CTRL38.exe, it seems the bankswitching is now set as default, so I just need the -c1 switch for linear 48k ram carts. I've got the 144k (78S9) binaries to work, most of the 128k (78SG types) also work now. But Dark Chambers, which is listed as 78SG cart, does not work at all, the upload goes through but if I start the game, I just get static or a black screen. I didn't find any information on Dark Chambers using something other than Ataris standard bank switch and the binary file does work using the emulator.

 

Is there any explanation for this behavior?

[X5900]

I've made a clean dump from a Dark Chambers PAL version and this solved the problem, seems the ROM files of the PAL version on the internet are bad.