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Help identify chip type #105551 05/12/16 10:47 PM
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mizapf Offline OP
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Here is a picture of the Superfly cartridge for the TI-99/4A console from Milton Bradley.

Ninerpedia:Superfly cartridge

All MB cartridges use the same kind of PCB. The biggest chip on this board is supposedly the ROM. The two smaller ones top/middle are GROMs; the two ones top/right are RAM circuits. Top/left is a latch that is used for bank selection in the ROM.

I could not find specs for the big chip. I guess it is a 32Kx8 ROM. The NCR number (8342A) is different for each cartridge. The only constant seems to be the 1500536.

Re: Help identify chip type [Re: mizapf] #105554 05/13/16 07:08 AM
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8342 is the date code (year 1983, week 42). Can you trace some of the lines (vcc, gnd, chip enable, chip select) to see to which pins they connect?

Re: Help identify chip type [Re: mizapf] #105563 05/13/16 10:59 PM
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Last edited by smf; 05/13/16 10:59 PM.
Re: Help identify chip type [Re: mizapf] #105568 05/14/16 11:29 AM
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mizapf Offline OP
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I believe it could be a M27C256B OTP ROM, judging from the PCB traces. I just received a photograph of such a cartridge with all circuits removed, so I'll see whether this proves to be right.

Re: Help identify chip type [Re: mizapf] #105580 05/15/16 10:31 AM
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mizapf Offline OP
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OK, so according to my analysis, this should be a 27C128 (16Kx8). The only pin I was unsure about is pin 27 which is connected to Vcc on the PCB.

On a 27C256 this would be A14, but on the 27C128 this is PGM*.


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