Due to Mach210 timing code it will not be possible to add more than 64mb of ram. What I did was this: I grabbed 2 signal from simm 1 (RAS0/RAS2) & (RAS1/3) and 2 other signals with the same designation from simm 2 and combined all those 4 into just 2.
Apollo 1240/60 64 mb single simm
- Thread starter Marmes
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embedder
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Also having interest in one piece.
embedder
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I would take two pieces if the minimum required amount of ordering persons is not reached.
llilith_silver
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Hi, I am interested in this piece of hardware too.
Nice work !!!
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Hi, I am interested in this piece of hardware too.
Nice work !!!
embedder
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GREAT!!!!OK! Boards are being made now1
:woot::woot::woot::woot::woot::woot::woot::woot::woot::woot::woot::woot::woot:
stupid PayPal.Hi,
I admire what you have done here and I am sure I will do the same modification to my Apollo 1240 but I wonder one thing. Why did you use a GAL here when taking a look at your boolean equiations it seems to me this could be done with an AND gate chip instead of the GAL (e.g. 7408 has 4 and gates and you need only 2 of them. RASOUT0=RAS0&RAS1 RASOUT1=RAS2&RAS3). Have you considered this option?
I admire what you have done here and I am sure I will do the same modification to my Apollo 1240 but I wonder one thing. Why did you use a GAL here when taking a look at your boolean equiations it seems to me this could be done with an AND gate chip instead of the GAL (e.g. 7408 has 4 and gates and you need only 2 of them. RASOUT0=RAS0&RAS1 RASOUT1=RAS2&RAS3). Have you considered this option?
Do you mean two input wires to GAL and 2 outputs? I am thinking what can be the trick of your simplification when the MAC210 has 2 separate RAS lines to each SIMM modules. Is it a secret or would you tell us?
I am definitely going to make this modification to my Apollo.
I am definitely going to make this modification to my Apollo.
@ishe
From my research in to Marmes 64MB Apollo project it does come down to timing of the MAC chip, there isn't enough time available by the MAC to multiplex an additional RAS for an upper 64MB or a 128MB SIMM.
Sadly the above timing issue is I believe is only presented when testing / implemented hence the need for a GAL
From my research in to Marmes 64MB Apollo project it does come down to timing of the MAC chip, there isn't enough time available by the MAC to multiplex an additional RAS for an upper 64MB or a 128MB SIMM.
Sadly the above timing issue is I believe is only presented when testing / implemented hence the need for a GAL
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@Zetr0
Ok, but you are talking about an expansion which is more than 64Mb. I am satisfied with a solution which makes one 64Mb modul work in one socket. That means we have to connect the missing address lines from the 2nd simm socket to the 1st simm socket and combine the ras lines so that it is asserted in the 1st simm socket also when it is asserted in the 2nd socket. I however have to investigate it a bit more deeply...
Ok, but you are talking about an expansion which is more than 64Mb. I am satisfied with a solution which makes one 64Mb modul work in one socket. That means we have to connect the missing address lines from the 2nd simm socket to the 1st simm socket and combine the ras lines so that it is asserted in the 1st simm socket also when it is asserted in the 2nd socket. I however have to investigate it a bit more deeply...
embedder
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Thx for the update & many thx for the great job!
Here it is. I am testing it for 24 Hours without turning the amiga off.
memcheck 10x returned no error. ATF22V10C turns a bit hot due to its size. Trapdoor closes well, if I had a thinner simm it would be even better. I have several delay positions, so you can adjust acording to the ram you use.
Hope tomorrow amiga is still alive
, it's been working since 10PM GMT.
If anyone is interested next I will have 6 boards available , but meanwhile here are some photos. Bear in mind that this apollo was my test board, it's working 100%, but not so beautiful.
memcheck 10x returned no error. ATF22V10C turns a bit hot due to its size. Trapdoor closes well, if I had a thinner simm it would be even better. I have several delay positions, so you can adjust acording to the ram you use.
Hope tomorrow amiga is still alive
, it's been working since 10PM GMT.If anyone is interested next I will have 6 boards available , but meanwhile here are some photos. Bear in mind that this apollo was my test board, it's working 100%, but not so beautiful.
