20 Dec
2005
20 Dec
'05
2:03 a.m.
Subject: Re: Partially-bad chips; was: repairing early HP calcs
From: "Chuck Guzis" <cclist at sydex.com>
Date: Mon, 19 Dec 2005 17:52:21 -0800
To: cctalk at classiccmp.org
On 12/20/2005 at 12:15 AM ard at p850ug1.demon.co.uk wrote:
>I remember a UK company called Bi-Pak. They bought up defective ICs,
>tested them [1], and sold them. They did sell things like TTL quad-gate
>packages with only 3 good gates. Problem was, as we all found, those 3
>gates quickly failed in use.
Polypaks was the place here. No bargan as usually a package with one bad
gate developed other problems over time.
Back in the days when DRAM was precious, Intel had some
"8Kx1" DRAMs that
were really "half good" 16K parts. You used the "-x" digit to
determine
which half to use. I don't know if these were in general circulation, but
the sales engineers were passing them out to customers working on designs.
I may still have one or two kicking around that I found actually had 16K
worth of usable bits, providing they weren't run too fast.
I used to have a full set of half good 64ks, likely still do.
And there was bubble memory with a flaw map.
That was normal. It had extra tracks for that reason. I must have 8
of the BMs and two working BPK72 boards. There was no such thing as
a flawless BM apparently.
Aren't some (or all) high-density DRAMs now made
with extra rows and colums
to improve yields?
Used to be so, don't know about it now.
Allison
20 Dec
20 Dec
2:27 a.m.
On 12/19/2005 at 9:03 PM Allison wrote:
Polypaks was the place here. No bargan as usually a
package with one bad
gate developed other problems over time.
I really had to wonder about some of the Poly Paks stuff--you could get
IC's with untinned/unplated leads or other very substantial cosmetic
defects. Still, I certainly bought a pile of RTL from them--all flat-pack.
--Chuck
That was normal. It had extra tracks for that reason.
I must have 8
of the BMs and two working BPK72 boards. There was no such thing as
a flawless BM apparently.
Still have an unused BPK72A-4 in its original box (S/N 948). Sales guy
gave it to me--I didn't ask for it, could never rationalize using it
for--what, 128K of rather slow power-hungry memory. I think Intel grew
desperate at some point to find a market for it.
--Chuck
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