hp42s memory upgrade

[Nat]

Hi,

I'm thinking of upgrading the memory in my 42s, I have read the info on this site about it but was wondering if anyone can properly identify this ic for me "um61256fs-15" and does it have low standby power? I can not find a data sheet for it. Basically, is it suitable?

Thanks
Nat

[Nat]

Anyone??

[Vieira, Luiz C. (Brazil)]

Hi, Nat;

I tried finding the specs of the memory chip you mentioned, but I did not succeed. Sorry!

Anyway, I mannaged to upgrade some units, and I tell you that the chips I found and used mainly had their ID ended with '70' instead of '15'. I have two H48G carcass in hands right now and they have the following 32K-RAM chips:

CXK58257AM-70L  (SONY)

W24257S-70LL    (WINBOND)

I removed two from an ancient sound card that comes with three units, with the following ID:

MT62C256F-70LL

I also used other units, and at least one of them was UMC made, as the one you mentioned. And I tell you that at least the HP42S' I used for a while (three units, now I have two) did not show any noticeable difference in power consumption wiht the RAM chips I used. I think that the '70' in the end of the ID's refers to access time (70ns), and that the 'L' and 'LL' may also refer to low power. If yours is a 15ns because of the '15' in the end of the ID code it means it may work because I remember removing some 8K RAM chips in some HP42S with ID codes ending with '15' as well. But the lack of a 'L' and the end of it may suggest that they are not actually low power. Because all RAM chips I used from the HP48G had the '70' in the end of their ID codes, I guessed that using the same chips in the HP42S would work. Well, I had no problems so far. I upgraded more than ten units, no complaints.

Sorry if I have no additional information about the RAM chip you mention in your post (um61256fs-15). The only reference I found here is a brief description of it as being a CACHE RAM 32Kx8 15ns. Anyway, I could not use any cross-reference about the ones I used, I mainly checked if their terminals were functionally the same prior to use them.

Cheers and success.

Luiz (Brazil)

Edited: 6 May 2006, 11:25 p.m.

[Vieira, Luiz C. (Brazil)]

Hi, Nat;

I searched the MoHPC Forum Archieves and found this thread with some additional info. Maybe this is the one you have already read...

Cheers.

Luiz (Brazil)

[Peter Geiser]

The Chip has been made by UMC

Perhaps they can help you.

It seems that the datasheet is available at:
http://www.datasheetarchive.com/search.php?q=um61256fs-15&sType=part&ExactDS=Starts

Best regards

Peter

[Nat]

Thanks to you both for trying help, I have contacted this site "http://www.datasheetarchive.com/search.php?q=um61256fs-15&sType=part&ExactDS=Starts" but no luck yet.

Thanks again
Nat