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Old 16 September 2020, 17:46   #541
solarmon
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Quote:
Originally Posted by PeteAU View Post
It might be difficult to achieve with one DPDT switch, but I think you could get total system ram to 512k if:

- JP4 on Gary adapter to "512K".
- EXRAM disconnected on trapdoor board (some had a switch or jumper). This is also JP7A on motherboard. This causes all SLOW ram to disable.
- Might need to re-link JP2 to 0.5 chip position (?) - not sure.
It seems all I need to do is disconnect the SEL0 and SEL1 lines going from the Gary adapter to the Datel Ram-Master II card (which seems to be the equivalent of un-jumpering JP1 and JP2) - this gives me 512K Chip only, and memory tests in ATK are passing.

So at least I know where is a way to quickly/easily 'degrade' the setup with just a switch.
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Old 05 October 2020, 06:22   #542
CommCollector
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Hi everyone,
First time poster to this great group. I have been reading this thread with great interest and would love one of these to compliment by amiga 500 rev 6a
I don't have the time to order all the bits and skill to make one up to so ordered one from amigastore . Unfortunately there local postage service is not shipping to Australia at the moment.
Would anyone on this thread have a spare working current version assembly that they would be willing to sell to me if possible that would be appreciated.
Thanks in advance.
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Old 17 October 2020, 08:31   #543
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Working great in rev6a. End result 1mb chip & 1.5mb slow! At first I was thinking to populate the empty ram slots on the board (I soldered the dip sockets) but when I played around with this trapdoor ram and discovered the configuration for 2.5mb total I went that way AND you get a RTC, too.
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Old 27 October 2020, 22:48   #544
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Yep, and that is why i'm using this ramexpansion for every A500 Rev 6a
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Old 30 November 2020, 10:07   #545
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Hi!
I can confirm the Rev C6 with SOJ-40 is working for me on my A500 Rev 6a with TF534 on. I've built the expansion with 4 memory chips in order to have full 1MB Chip plus 1.5 MB Slow plus 4 MB Fast of the TF.

Thank you all for sharing your experiences, it helped me a lot!
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Old 04 February 2021, 15:12   #546
Ninjafahrer
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Peteau Amiga 500 Rev 6A

Out of curiosity:
I have a A500 REV 6A with 1MB Chipram onboard.
If i have the fully quipped PCB (4 RAM Chips) and the GARY Adapter do I get 2MB of slow RAM in addition of the 1MB Chipram at the REV 6A Board?
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Old 10 February 2021, 19:10   #547
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Picture Backsite

Can someone please upload a picture of the Backsite?

I am interested on where the Tantalum capacitor needs to be placed.
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Old 10 February 2021, 20:57   #548
SukkoPera
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C19.
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Old 10 February 2021, 23:52   #549
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Thanks, just wondered where the PLUS pole should be, but I was checking it with a coin cell and a multimeter.

Last edited by Ninjafahrer; 11 February 2021 at 00:55.
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Old 11 February 2021, 13:36   #550
SukkoPera
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IIRC, the positive pad is the one in line with the chip pins.
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Old 19 February 2021, 11:26   #551
Alexco
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Hi, I have a Rev6a with 2MB Chip RAM on board, modification is described here:

http://www.rasterline.com/images/ami..._2MEG_CHIP.jpg

Is it possible with this expansion and Gary adapter to have 512k Ranger/Slow mem at $C00000, just for compatibility?
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Old 19 February 2021, 12:31   #552
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You will probably have to implement the reslow circuit.

This thread has the original on page 1 and some modern implementations on the last page
http://eab.abime.net/showthread.php?t=31816
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Old 19 February 2021, 17:21   #553
Alexco
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Really? I thought it is all covered with the Gary adapter and the expansion board logic.
The reslow circuit seems not finished, at least no one could fix the instability (as far as I can see).
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Old 28 February 2021, 21:54   #554
Ninjafahrer
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I have a A500 PLUS REV 8A with 1MB Chipram onboard.
If i have the fully quipped PCB (4 RAM Chips) and the GARY Adapter do I get 2MB of slow RAM in addition of the 1MB Chipram at the REV 8A Board?
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Old 28 February 2021, 23:55   #555
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No, you can only get 1 MB extra chip RAM.
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