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Micronik RA-501
Posted: 12 Oct 2020 12:38
by GianDO
Hi,
I found a Micronik RA-501 to expand the A2000 chipram to 2MB, but I don't have the schematic to connect the two wires to Gary chip. If any of you have it, could you please provide it to me?
Regards
GianDO
Re: Micronik RA-501
Posted: 12 Oct 2020 18:50
by terriblefire
Best chance is looking at
100_3011.jpg
Which looks to me to connect to pins 38 and 37 below..
gary-pin-out-amiga.png
Which would make sense. It probably doesnt matter too much which order they are in. Or at least it will not do damage if the order is reversed since the extra ram would just be used in a different pattern. If you find its not happy try swapping them.
Re: Micronik RA-501
Posted: 12 Oct 2020 19:02
by terriblefire
Quick maths check...
To address 2Mb of RAM you need 22 bits A[21:0] so my guess would be those are connected to A21 (37) and A20 (36).
A similar product is also hooking wires to this chip.
https://pmsoft.nl/amiga/mega-chip-two.html
Like i say you will not cause damage by connecting to the wrong address pin (provided you stay on an address pin) but it may not function as expected.
Re: Micronik RA-501
Posted: 12 Oct 2020 19:31
by GianDO
ok, thanks for the reply.
So do I have to unplug Gary's pin 32 as well as shown in the last photo?
Re: Micronik RA-501
Posted: 12 Oct 2020 19:37
by terriblefire
GianDO wrote: 12 Oct 2020 19:31
ok, thanks for the reply.
So do I have to unplug Gary's pin 32 as well as shown in the last photo?
No that just happened to be in the image i found. You can ignore that.
Re: Micronik RA-501
Posted: 12 Oct 2020 20:40
by GianDO
ok thanks I'll try to follow your instructions.
Re: Micronik RA-501
Posted: 12 Oct 2020 20:42
by terriblefire
GianDO wrote: 12 Oct 2020 20:40
ok thanks I'll try to follow your instructions.
Please let us know how you got on and what worked/didnt.
Re: Micronik RA-501
Posted: 13 Oct 2020 08:45
by terriblefire
Adding some more pictures i found of this board
Mikronic RA-500 front.jpg
Mikronic RA-500 Back.jpg
5.JPG
Re: Micronik RA-501
Posted: 13 Oct 2020 09:19
by terriblefire
Looking at the last image I count (please check me) the 12th and 13th pin from the top as the address pins...
That ties up to my theory of pins 36 and 37. (Again please check me).
Re: Micronik RA-501
Posted: 12 Nov 2020 14:35
by GianDO
terriblefire wrote: 13 Oct 2020 09:19
Looking at the last image I count (please check me) the 12th and 13th pin from the top as the address pins...
That ties up to my theory of pins 36 and 37. (Again please check me).
You were right about everything. I made the connections as you suggested and everything worked fine. Thanks for the advice and suggestions.
Also I confirm that even if you reverse the connections Gary everything works fine.
Thank you very much
G