Figured it all out. The IIx would probably read all 20mb.
But the II, which is all I have to test these with right now, is a very early first run. It has an HMMU and needs an PMMU upgrade to address more than 1mb SIMMS in bank B. Otherwise 8mb is the max. The kicker is the socket. One has to pull the board and look under. 132 through hole pins is good for this socket. Around 70 is bad, that means the socket is HMMU specific and will not accommodate an PMMU upgrade. And since my board is early, I will not bother even looking. Apple did have a swap program in place for these boards. This also explains why there are a couple revisions for this board and why so few originals exist. (A shame since the originals used solid caps, no electrolyte leakage!)
One work around is to install an 030 upgrade card. I think the 030 has a built-in memory manager and can address the extra RAM - up to 128mb.
But since I can see 8mb, odds are they all work. Now I just need to get a working IIx board to put these back in their proper home.
But the II, which is all I have to test these with right now, is a very early first run. It has an HMMU and needs an PMMU upgrade to address more than 1mb SIMMS in bank B. Otherwise 8mb is the max. The kicker is the socket. One has to pull the board and look under. 132 through hole pins is good for this socket. Around 70 is bad, that means the socket is HMMU specific and will not accommodate an PMMU upgrade. And since my board is early, I will not bother even looking. Apple did have a swap program in place for these boards. This also explains why there are a couple revisions for this board and why so few originals exist. (A shame since the originals used solid caps, no electrolyte leakage!)
One work around is to install an 030 upgrade card. I think the 030 has a built-in memory manager and can address the extra RAM - up to 128mb.
But since I can see 8mb, odds are they all work. Now I just need to get a working IIx board to put these back in their proper home.