A500 1mb upgrade chips available

kipper2k · 10 August 2012, 13:55

Hi all,

I a,m able to get my hands on Fujitsu MB81c4256 20 pin DIP Ram chips. For those people that have a A500 Rev6 board or higher this means you can add an extra 512k directly to the motherboard to give you 1mb chip ram. I can buy in quantities of 100 which means that if at least 25 people are interested then i can order them. Feel free to add additional info in the thread if there are caveats etc
The cost per chip is $5.50, (my cost would be $4.53 + duties etc). You would need 4 chips to complete this mod and 4 sockets. Add your name to the list below if you are interested

duga · 10 August 2012, 15:04

I would rather perform the motherboard modification to be able to use the trap door memory as chip ram. It seems to be easier for a solder novice and the trap door card gives me the benefit of RTC.

TjLaZer · 11 August 2012, 06:43

Can this upgrade give you 1MB chip ram?

prowler · 11 August 2012, 21:56

Hi Kipper,

I have sixteen KM44C256BP-8 chips which I bought from PowerPie5000 (IIRC) for upgrading A500 Rev6+ boards to 1MB chip RAM, but I suppose there must be more to it that just adding 4 chips in the vacant spaces, and so that's why the chips are still in the box in which I received them.

Also, I'm not sure that adding these chips doesn't prevent furher expansion via the trapdoor. Would you happen to have any further info on this upgrade, please?

zipper · 11 August 2012, 23:49

I think the mobo empty sockets and trapdoor use the same address.

prowler · 11 August 2012, 23:52

Quote:

Originally Posted by zipper

I think the mobo empty sockets and trapdoor use the same address.

That's what I suspect.

Jope · 12 August 2012, 15:57

No need to suspect anything, they are indeed the same RAM.

There is a schematic floating around where you can have 1MB chip on the motherboard and still have 512k ranger fast in the trapdoor, but people haven't had very good success with it.

prowler · 13 August 2012, 20:05

Thanks for the info, Jope.

10 August 2012, 13:55	#1
kipper2k Registered User Join Date: Sep 2006 Location: Thunder Bay, Canada Posts: 4,323	A500 1mb upgrade chips available Hi all, I a,m able to get my hands on Fujitsu MB81c4256 20 pin DIP Ram chips. For those people that have a A500 Rev6 board or higher this means you can add an extra 512k directly to the motherboard to give you 1mb chip ram. I can buy in quantities of 100 which means that if at least 25 people are interested then i can order them. Feel free to add additional info in the thread if there are caveats etc The cost per chip is $5.50, (my cost would be $4.53 + duties etc). You would need 4 chips to complete this mod and 4 sockets. Add your name to the list below if you are interested

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10 August 2012, 15:04	#2
duga Registered User Join Date: Nov 2010 Location: Sweden Posts: 528	I would rather perform the motherboard modification to be able to use the trap door memory as chip ram. It seems to be easier for a solder novice and the trap door card gives me the benefit of RTC.

11 August 2012, 06:43	#3
TjLaZer Registered User Join Date: Sep 2004 Location: Tacoma, WA USA Age: 52 Posts: 1,924	Can this upgrade give you 1MB chip ram?

11 August 2012, 21:56	#4
prowler Global Moderator Join Date: Aug 2008 Location: Sidcup, England Posts: 10,300	Hi Kipper, I have sixteen KM44C256BP-8 chips which I bought from PowerPie5000 (IIRC) for upgrading A500 Rev6+ boards to 1MB chip RAM, but I suppose there must be more to it that just adding 4 chips in the vacant spaces, and so that's why the chips are still in the box in which I received them. Also, I'm not sure that adding these chips doesn't prevent furher expansion via the trapdoor. Would you happen to have any further info on this upgrade, please?

11 August 2012, 23:49	#5
zipper Registered User Join Date: Mar 2004 Location: finland Posts: 1,839	I think the mobo empty sockets and trapdoor use the same address.

12 August 2012, 15:57	#7
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,877	No need to suspect anything, they are indeed the same RAM. There is a schematic floating around where you can have 1MB chip on the motherboard and still have 512k ranger fast in the trapdoor, but people haven't had very good success with it.

13 August 2012, 20:05	#8
prowler Global Moderator Join Date: Aug 2008 Location: Sidcup, England Posts: 10,300	Thanks for the info, Jope.

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