battlezone ROMs (original)

marc.hull

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In my weekend quest I have gotten to the point of testing the ROM. My EPROM tool doesn't recognize then little 2K jobbers so I made a cartridge for my TI to read the contents of them.

Address lines and data lines are mated correctly. I have CS0 tied low and CS3 tied high. CS1 is connected to the computers *CE line for the cart space. Without a ROM in the ZIF I read zero's across the space (what I expected.) With a ROM installed (Only tried 1 and only for a brief moment just in case) I read 255 on each byte.

I do not have the data lines buffered as I think the ROM should drive the buss (and it appears it is hence the 1111 1111's I am seeing.

Now I need help in interpreting what I am seeing.

Is $FF on all locations (or the 20 or so I watched go by) a good indication of a faulty ROM ?

Is my problem perhaps related to the ROM's inability to drive the buss directly ?

If access time were an issue on the ROM's I would expect the data to be at least somewhat random. Am I wrong here?


I would rather not test any others until I am a little more confident in this methodology.


Finally the ROM pin outs as I am using them. Gosh I hope these are correct.

1-8 A7-A0
9-11 D0-D2
12 GROUND
13-17 D3-D7
18 CS0
19 A10
20 CS1
21 CS3
22-23 A9-A8
24 +5V

Thanks.

Marc
 
BZ EPROMs should be 2716s. Pull 18 (/OE) and 20 (/CE) low to read. Tie 21 (Vpp) high.
 
Thanks but what I have are either masked ROMS or PROMS. Cant find a data sheet on the number so I imagine they are ROMs. I have it wired just like the PCB schematic does with pin 21 tied high, pin 18 tied low and pin 20 connected to *CE from the computer.

Perhaps I made a mistake reading the schematic. It's pretty small print and my eyes are not as they used to be. I'll double check this evening and report back.
 
Mask ROM, bi-polar PROM, OTP EPROM, no matter... read it as a 2716.

What EPROM programmer do you have? 2716 is a fairly simple and common EPROM (no tri-voltage, or non-standard pinout), so I'm a bit surprised that there's a unit that won't read it.
 
Mask ROM, bi-polar PROM, OTP EPROM, no matter... read it as a 2716.

What EPROM programmer do you have? 2716 is a fairly simple and common EPROM (no tri-voltage, or non-standard pinout), so I'm a bit surprised that there's a unit that won't read it.

Wellon VP-190. Chinese nomenclature for POS.... ;-)....

OK then I'll check this cart and make sure I wired it correctly and proceed with abandon...
 
So I got my ROM reader rig up working and fixed (bad address line wiring) and my software goof up taken care of so now I can read the ROMs onto my TI save them to floppy and convert them to PC format. So far I have just dumped the A3 ROM which is numbered 36421-01. Took about 20 minutes to do it in TI BASIC. Good thing I had games to play ;-)....

I also downloaded a corresponding ROM from a MAME warez site and compared the two. They are nothing alike. Attached is what I pulled off the ROM I have in a text document. I dumped it 3 times and got matching dumps all 3 times so I am confident the set up works.

I could check the data lines and make sure they are correct. 6502 LSb is still D0 correct ?

If someone could take a look at my dump and tell me if it is at all recognizable I would appreciate it.

Thanks.

Marc
 

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