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Old 06 November 2014, 21:51   #1
cabal
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Homemade A500 trapdoor expansion?

On Aminet I found this http://aminet.net/package/docs/hard/Tabajara, its to make a A600 trapdoor expansion using a 72 pin simm.

I thought maybe this could also be used, with some adjustments, on a A500.

Would/could the following work:

connections from trapdoor to a 72 pin SIMM 4Mb


XDRD0-XDRD15 to DQ0(DQ16)-DQ15(DQ31)

A0-A8 to A0-A8

CASL to CAS0 and CAS2

CASH to CAS1 and CAS3

RAS1 to RAS0 and RAS2

WE to WE

+5V to VCC

GND to GND


and also the EXRAM pin from the A500 connected to GND so the expansion would get recognised.
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Old 07 November 2014, 08:49   #2
Yulquen74
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what is your goal with the project?

creating a 0,5MB/1MB slowfast/chip board similar to A501/A501+, or adding the 1,7mb slowfast ranger RAM as well (that will require a Gary hack)?

or is it simply for fun using a 72 pin simm instead of DIP DRAM's?
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Old 07 November 2014, 11:11   #3
Yulquen74
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Looking at the original project it adds an additional MB of chipram to an A600.

Converting this project to A500, it would only add 1 MB of chipram to an A500+,
since that machine is fitted with a 8375 Agnus capable of addressing 2MB's of chip.
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Old 07 November 2014, 16:09   #4
cabal
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Quote:
Originally Posted by Yulquen74 View Post
what is your goal with the project?

creating a 0,5MB/1MB slowfast/chip board similar to A501/A501+, or adding the 1,7mb slowfast ranger RAM as well (that will require a Gary hack)?

or is it simply for fun using a 72 pin simm instead of DIP DRAM's?
Both kinda and its also a cheaper altenative to a A501/A501+.

Once it works as a A501, adding the 1,7mb could be the next step.
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Old 01 December 2014, 15:50   #5
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Got some time this weekend and made myself a A501 clone with a 4 mb simm and it works great.
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Old 01 December 2014, 22:44   #6
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Sweet Can you post some pics?
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