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gazzmaniac / Amiga-SMD-500

An SMD verson of the great Amiga 500
CERN Open Hardware Licence Version 2 - Strongly Reciprocal
66 stars 13 forks source link

JP98 RAS joined won't work #3

Open LIV2 opened 4 years ago

LIV2 commented 4 years ago

Hi, first of all great work! Love the project

Just thought I'd let you know that recently I was making a Megachip clone for the A500 and found that joining the RAS lines just resulted in a green screen. I had to make use of an AND gate to get this working - an 74AHC1G08 in my case.

Presumably this is because the RAS lines are not open-collector and fight each other when you simply join them together

mariuszk911 commented 4 years ago

Or just use two diodes... Like on 2M Mod for 8A1 using SOJ memory modules.

gazzmaniac commented 2 years ago

I never did get the single ram IC solution working. I'm looking at doing a revision later in the year and will have chip ram on two chips.