adding 4mb SGRAM to PowerPC 5500/6500 ... and possible ATi Rage Pro upgrade

[Phipli]

So I think that you only need to lift 1 pin because two pins of interest are both NC.

You need to fit appropriate VRAM and Rage Pro chips, then existing MMA (9) to pin 30 on the VRAM, then connect pin 206 from the Rage Pro to pin 45 and lastly 28 on the Rage to 29 (needs lifting or it will be also tied to MMA(9) at the same time) on the 4MB VRAM.

Should fit inline resistors for the two new lines to match the MMA resistors on existing connections.

Resistors look to be 51R.

Hum, to simplify the mod, it wouldn't be the 100% OEM approved method, but I bet you could get away with just wiring Ati pin 206 to to VRAM pin 30 via a 51R resistor and ATi pin 28 VRAM to pin 45 via a 51R resistor.

That would be two resistors and the outputs from the resistors going to both VRAM chips.

It would mean that in a continuous copy you would bank swap multiple times instead of just once but... Well, if the normal arrangement is multiple chips, it might not make much if any difference really.

It would be an easier mod. No pin lifting needed.