1Mx4 DRAMs (was Re: 8008 chips)

Ethan Dicks ethan.dicks at gmail.com
Mon Dec 15 22:35:17 CST 2008


On 12/15/08, Joachim Thiemann <joachim.thiemann at gmail.com> wrote:
> On Mon, Dec 15, 2008 at 5:43 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:
>  >>  Tell me about it.  I've been looking for 1Mx4-bit 20-pin DIP DRAMs for
>  >> years.  The closest I've come is some 26/20-pin surface mount.
>  >
>  > I have, too... I need 4 of them to upgrade my Rejuvenator in my Amiga
>  > 1000 from 1M of CHIP RAM to 2M of CHIP RAM (that and a "Fatter Agnus",
>  > but those aren't as difficult to find as the RAM itself).
>
> I've got some TC514258AP-80's (20-pin DIP), originally from the fast
>  RAM of my A3000 (replaced by ZIL (Zig-zag in-line?) chips). Those what
>  you need?  I think they're only 256kx4.

Those _are_ 256Kx4 (1Mbit) and that's what I have eight of in my
Rejuvenator now.  What I need to upgrade is four 1Mx4 (4Mbit) chips,
and, as a couple of us have been saying, those are somewhat uncommon.

Save yours for another Amiga, though - 514258s are, IIRC, "static
column" DRAMs and were not as common as 514256s (or 44256s, etc).
There is a measurable performance difference in an Amiga 3000 with
"plain" DRAMs vs "static column" DRAMs (5%? 10%?)  AFAIK, they will
work in an A2091 (and other Amiga memory boards) or some older ISA VGA
cards as regular 256x4 chips.

I already have a few 256Kx4 chips - we used to populate our VAXBI
COMBOARDs with 2MB of them, as did many Amiga A2091 and A590 owners
(and a few PC owners, IIRC).  Those chips aren't too hard to find in
DIP packages.  By the time 4Mbit dice were being produced, memory had
largely (but not entirely) moved on to SMT packaging.

-ethan



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