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Old 30 September 2007, 02:33   #1
Zetr0
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Memory Data Structures

Hello there forum chummies

I am currently redeveloping an A500 Fast Memory Upgrade fo use with an A600

to make this happen, I am changing the 8 1MB Banks of 30pin simm memory for 1 Bank of 72pin memory

some tech specs

30pin memory
  • 12 Address Lines (0-11)
  • 8 Data Lines (0-1)
  • 1 CAS (Column Address Strobe)
  • 1 RAS (Row Address Strobe)

72pin memory
  • 12 Address Lines (0-11)
  • 32 Data Lines (0-31)
  • 4 CAS (Column Address Strobe)'s
  • 4 RAS (Row Address Strobe)'s
  • 4 PRD (PRD1 - PRD4) (what is this I cannot remember)

Well heres my quandary, in restructuring the memory data I am at a well confusion...

my initial idea was to use the full data lines from D0 to D31 using CAS#0 and RAS#0 thus allowing my to 4 times as much data for each CAS/RAS level (since i am limmited on physical logica space *and 5v power*) I figured i could use CAS0/RAS0 for the first 4MB and then CAS1/RAS1 for the last 4MB (ie bank 2) for a total of 8MB

now the problem I have with that is the initial design (which is known to work) only has 50 DATA lines insted of an expected 64.

so i wonder where (a) I have borked it? and (b) am i attempting to use the 72pin simm data structure in the wrong way...

I could use some help guys
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Old 30 September 2007, 04:17   #2
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Okay, I now have the full 64 addressing lines that i need (total 8MB ram)

the question is, can i still use the accessing method i described above?
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Old 30 September 2007, 12:56   #3
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Many moons ago, I'm thinking late 386, early 486 era there was some kind of 30pin to 72pin SIMM convertors would one of those things not help you somehow?

http://www.berklix.com/scanjet/pics/ram_adapt.jpg

Mind you, looking at it, it seems a purely physical conncetion thingy.
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Old 30 September 2007, 15:24   #4
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@DrF

thats what i was thinking, indeed it just changes the data address / CAS 'n RAS lines!!!

whoot thanks buddy!!!!
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Old 30 September 2007, 15:34   #5
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So could you just get 1 of them and plug it in and thats it done?
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Old 30 September 2007, 16:17   #6
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@DrF

yes and no LOL

depending on the 72pin PORT I am *assuming* that the 30pin simms require to be all the same size and 1mb or higher (imagining that 4-8MB would be thier limmit anyway)
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Old 30 September 2007, 16:39   #7
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Only 1 true way to know :P
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Old 30 September 2007, 18:38   #8
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I remember those.. the different letters mean that they are a different height and point different ways so you could get four into adjacent 72pin slots. :-)

You must use the same size 30pin simms to populate one of those and naturally all four must be present.
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