08/06/89: 256K x 4 bit chips by Delphi, | Category: Delphi - Hardware Hacking | 5 comments - (Comments are closed)

256K x 4 bit chips

52702 6AUG89-1621 Hardware Hacking
256K x 4 bit chips

I recall you once explaining that the reason 256K x 4 bit chips could not be
used on the CoCo is because the CoCo does not support the refresh cycle needed
by these 1 megabit chips. (Wasn’t it 512-cycle vs. the normal 256-cycle)?

If this is what I think it is, there may be a way around it. If my memory is
not to rusty, there may be a way around this. When 256K upgrades first started
coming out for the Atari XL series, it was noted some of the earlier ANTIC
chips did not support the proper refresh. (In fact, I believe they mentioned
it only support 128-cycle, and 256-cycle was needed). As a result, some mods
included a circuit to provide the refresh extension.

I would expect this would work for the CoCo as well, if I have my info straight.

And with 256Kx4 chips going for as low as $15, and 256Kx1 chips going for
about $6 each, some savings could be realized even if the extra chips needed
(I believe the Atari circuit took 3) ate up the savings in power and board

BTW, I don’t plan on doing anything about this if this is possible, as I
already have a 512K upgrade. But I thought some prospective board maker out
there might be interested in if my thoughts are correct…which would mean a
256Kx4 bit chip 512K upgrade would be economically feasible.

b-back, LEM

5 comments to 256K x 4 bit chips

  • pucc_unknown

    52727 7AUG89-0144 Hardware Hacking
    RE: 256K x 4 bit chips (Re: Msg 52702)

    I’m sure there is some sneaky way to add the extra count. The
    question is… can it be done ECONOMICALLY???

    256K by 4 for $15 ??? Tell me where you saw them at that price.
    I find that VERY hard to believe. I doubt one can get them for
    less than $25 each. The Jaemco price is closer to $60.

    Note that a FEW may pop onto the surplus market… or appear
    at flea markets… for very low prices. BUT… this does
    not represent a reliable source!

    Tell me more about 256K by 4 for $15. I might be willing to buy
    a few thousand… I may be able to sell them for $30 here
    pretty quickly.


  • pucc_unknown

    52756 7AUG89-2331 Hardware Hacking
    RE: 256K x 4 bit chips (Re: Msg 52727)

    Well, let me check my latest issue of Computer Shopper. (He thumbs though over
    600 pages while the pennies drop rapidly down the black hole called Delphi…)

    Okay, here is the first IC place I found. Page 178 of the August issue, I.C.
    Express: 256Kx4, 100ns, $15.75. (lists it as a 514256). Let’s try another…

    Arrgghh, remember the name of another one, but they dont’ caryry the 256Kx4 bit
    part. Most of the best prices are found in the small ads, and are a lot harder
    to find than I.C. Express was.

    Ah..ha. Here’s another…on page 585. Unitex. 256 x 4 – 120ns, $15. (100ns from
    them is $17).

    What kind of cut do I get on the deal? .

    b-back, LEM