Partially-bad chips; was: repairing early HP calcs

[Dwight Elvey]

>From: "Jim Battle" <frustum at pacbell.net>
---snip---
>
>Redundancy in DRAM, row and column, has been in use for 20 years at least.  At 
>the ASIC level, largish SRAMs typically also have redundant rows and columns 
>(largish meaning more than a few kbits).
>
---snip---

Hi
 I don't want to bust anyones bubble but many low end computers
sold as desk tops have partially bad chips. The term used
is "down graded". It is still standard practice in the industry.
Many of you may have a down graded part in your machine and
not even know it.
 Manufactures stop down grading when the yield is high enough
that it is no longer economical to deal with the down graded
parts. The extra handling cost money as well.
 It is simple economics.
Dwight