29F016 on 2A3B (2 Maskrom) Donor

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twitch
Posts: 11
Joined: Sun May 22, 2016 9:29 am

29F016 on 2A3B (2 Maskrom) Donor

Post by twitch »

Hi Folks!

i have several 2A3B PCB laying around and im asking myself if i can just put a 16Mbit TSOP in Maskrom1(U1) and leave Maskrom2(U2) empty?

For example: Parallel World? (LoRom 64k)

Will this work and is there any wiring needed on the 74LS?

Rgds Dario
Ice Man
Posts: 547
Joined: Fri Jul 04, 2014 2:34 pm

Re: 29F016 on 2A3B (2 Maskrom) Donor

Post by Ice Man »

You have to rewire the 74LS139 since 2A3B only has 32 pin MaskROMs.
You'd need to make up for A20/A21 decoding when using a TSOP Adapter with 36 pins.
twitch
Posts: 11
Joined: Sun May 22, 2016 9:29 am

Re: 29F016 on 2A3B (2 Maskrom) Donor

Post by twitch »

You are right,thanks - so i could use 2 27801 and rewire!
Ice Man
Posts: 547
Joined: Fri Jul 04, 2014 2:34 pm

Re: 29F016 on 2A3B (2 Maskrom) Donor

Post by Ice Man »

Yea, that would be the better method for those boards. :P
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