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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Prosatanos on August 04, 2009, 05:20:27 PM

Title: A500 ram expansion
Post by: Prosatanos on August 04, 2009, 05:20:27 PM

Hi!
 
My A500 have 512k internal memory soldered on board. I decide, to solder another 4 chip (512k) memory to it. Will the new ram auto added, or i need to insert jumpers, or etc.?
 
I have 512k external memory expansion board. After the soldering, it is possible to have of total 1.5Mb ram?
 
Thx

Title: Re: A500 ram expansion
Post by: dougal on August 04, 2009, 07:05:03 PM

Quote from: Prosatanos;517996

Hi!
 
My A500 have 512k internal memory soldered on board. I decide, to solder another 4 chip (512k) memory to it. Will the new ram auto added, or i need to insert jumpers, or etc.?
 
I have 512k external memory expansion board. After the soldering, it is possible to have of total 1.5Mb ram?
 
Thx

First you have to see what revision A500 motherboard you have ?

Title: Re: A500 ram expansion
Post by: Prosatanos on August 04, 2009, 07:31:02 PM

Quote from: dougal;518005

First you have to see what revision A500 motherboard you have ?

Hi!
 
A500 Rev 6A Agnus: CSG 8372A 318069-02
A500+ Rev 8A Agnus: CSG 8375 390544-01

Title: Re: A500 ram expansion
Post by: Zac67 on August 04, 2009, 07:51:08 PM

Quote from: Prosatanos;517996

I have 512k external memory expansion board. After the soldering, it is possible to have of total 1.5Mb ram?

No. While it is possible to use Agnus to expand beyond 1 MB (I'm assuming an A500 non-Plus here), you'd have to provide for some address decoding. The easiest way would be to get hold of one of these 2 MB boards - if you're using 1 MB as chipram, you'd have to make sure that the expansion board supports that setup.

Title: Re: A500 ram expansion
Post by: Prosatanos on August 04, 2009, 08:07:51 PM

Quote from: Zac67;518016

No. While it is possible to use Agnus to expand beyond 1 MB (I'm assuming an A500 non-Plus here), you'd have to provide for some address decoding. The easiest way would be to get hold of one of these 2 MB boards - if you're using 1 MB as chipram, you'd have to make sure that the expansion board supports that setup.

Thank You for the help again. When i right understand, if i solder 4 chips, i will have 1M ram anyway, but the expansion will not work, because Agnus limitation, without any further address decoding or hardware? (A500).
 
A500+ have 2MB Agnus?

Title: Re: A500 ram expansion
Post by: tone007 on August 04, 2009, 08:18:07 PM

Yup, 8375 is 2mb Agnus.

2mb chipram on an A500 is nice.  You can also do 1.5mb with a standard 512kb RAM expansion if you don't have a 1mb one around.

Title: Re: A500 ram expansion
Post by: Prosatanos on August 04, 2009, 08:57:47 PM

Quote from: tone007;518025

Yup, 8375 is 2mb Agnus.

2mb chipram on an A500 is nice.  You can also do 1.5mb with a standard 512kb RAM expansion if you don't have a 1mb one around.

Thank You.
 
Can sombody suggest any memtest prg for testing the soldered rams, under WB1.3.3?

Title: Re: A500 ram expansion
Post by: tone007 on August 04, 2009, 09:13:17 PM

A500 Final Test was a good one I remember, no idea if it's around online.

Title: Re: A500 ram expansion
Post by: Prosatanos on August 06, 2009, 06:42:59 PM

I have soldered the chips (A500). Nothing happen... Work as before. No more ram, no error, no heating, no smoke :). Using Samsung KM44C256BP-7 chips.
 
Any idea?

Title: Re: A500 ram expansion
Post by: Prosatanos on August 06, 2009, 09:20:19 PM

HeHe... It's working! :) You need to set JP2 to map the memory to $80000.
 
Thanks for the help !

Title: Re: A500 ram expansion
Post by: Prosatanos on August 11, 2009, 07:35:11 PM

A500 working too ! 1.5MB chip ram !