NANAO KNA91H014 (irem pallet ram chip) Repro - any interest?

[Hammy]

KNA91H014 (pallet chip) Repro

Seen on:
M72
M81
M82
M84
M85
M75 (vigilante)
more?

I have mostly reversed this chip...
The problem is the circuit is:

4X 74LS157
1X 74LS273
1X 74LS139
1X 74LS175
3X 74LS374
1X 74LS32
3X 74LS245
3X 2018

It needs to fit in a tiny space of 64 pins.

If anybody is good at FPGA and can condense this into a smaller device that's more workable please get in contact.

The smallest i can get the thing is the size of a credit card, it needs to be smaller still...

74ls07 in picture as a 'size guide' - this thing is about the size of 2 LS chips.. a tough order to fit all the above!

This can also be considered an 'interest check' if there is zero interest, it can stay as a breadboard

 

[Apocalypse]

I made myself the same reflection about how to substitute those RAMs. By a quick look at the documentation it seemed pretty simple but after reading your post with the multiple TTL chips needed it's clear I've overlooked it.

Anyway it seems simple enough to fit in a small FPGA, however schematics are needed for signals count but you may have already done the job.

[EDIT]
I doubt it will ever fit in place so best solution might be to design a flexible pcb adapter if you see what I mean.

 

[caius]

Yuu can condense the logics in a FPGA or other complex programmable logic devices but then the problem is always the same, how can you handle the original QFP package?IMHO these customs should stay as they are
By the way, some time ago I reproduced the custom resistor array used a RGB DAC always paired with the 'KNA91H014" :

http://www.jammarcade.net/vigilante-repair-log-and-irem-rgld8m472j221j-rgsd10l471g-reproduction/

 

[Hammy]

Thanks for the input! It's not an easy one, but needs to be done.

Here are the schematics. Signal names are taken from the RType 1 schematics.
There are unused gates on a lot of Ic's.

This is RAM NG 8 for all you M8x owners

As you see from the schematic, the plan at the moment is a long row of jumpers and wire tap them in at good via points.

 

[caius]

Good job.Did you take inspiration to some bootleg?For my 'KNA6034201' reproduction I studied how the custom was re-engineered in a replacement board made by Irem itself.

 

[Hammy]

A mixture of looking at various originals, r type bootleg, vigilante original & bootleg.

The 2 bootlegs do it slightly different, but the finished output is the same.