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29F016 on 2A3B (2 Maskrom) Donor

Posted: Wed Apr 26, 2017 12:16 am
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

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

Posted: Wed Apr 26, 2017 12:34 pm
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.

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

Posted: Wed Apr 26, 2017 11:20 pm
by twitch
You are right,thanks - so i could use 2 27801 and rewire!

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

Posted: Thu Apr 27, 2017 1:25 am
by Ice Man
Yea, that would be the better method for those boards. :P