31 Jul
2004
31 Jul
'04
2:06 a.m.
At 06:21 PM 7/30/04 -0700, you wrote:
(Looks again.) I found 27c256 and 27512 at 45ns at Digikey, and 45ns 27c512
at JameCo. Mouser also has the 45ns 27c256, but only has 55ns 27c512. (Are
you in the states?)
So, do these meet the requirements? (Seems like you could even burn several
different images into the chips and use a DIP switch to select which image
using the high address lines :-).)
Also needn't worry about holding reset, or batteries going dead, or a big,
complicated daughter board?
(I don't know the specs for the bipolar ROMs being replaced. Someone
earlier said they were 50-60ns. I am assuming they were also fairly small
(logically, if not physically) compared to a 27c256.)
The ones in the HP 1000 are 4 x 256 and are sixteen or eighteen (I
forget which) pin .3" wide DIPs. Al has pins out for some of the different
BiPolar PROMs on his site. I think they're under the games machines
section. There's no room for a duaghterboard to mount on the HP 1000 card.
You'd have to mount it elsewhere and cable over to it.
Joe
I must not be getting it, somehow.
Why can't you just use a 45ns or 55ns 27c256 or 27c512 and swizzle the
pinout? These are around $3 per chip, and seem to meet the requirements.
Vince
Hi
I did some searching on the web but never found any
27c256's faster than 70ns. I did find 27c512's and 27c010's
at 45ns a couple of places.
Dwight
Vince