Re: ROM-Drive Project Update

[Terence J. Boldt <apple2@cgocable.net>]

>used to visit are still in business. There is Active
>(not Active Surplus although that is always a fun
>place to look) and I know there are a number of
>electronic component stores. There are one or two
>on Queen Street West between Yonge and Spadina but

Active Electronics moved.  Anyway, they want almost $30 for
a 4Mb EPROM and don't sell the 8's.  Active Surplus and
Supremetronic (on Queen West) don't sell large EPROM's.
Sayal only has up to 4Mb.

Active Surplus is a fun store.  I got an enhanced IIe
(damaged case) for a couple bucks a few months ago.  I used
it for the power supply, motherboard and peripheral cards.

>If you can't find the 8 Mb EPROM, why not use
>two 4 Mb ones? For that matter, why not use four
>or more? You address decoding circuit would need
>to be altered a bit but you could offer larger
>capacity ROM Drives that way.

I did have a multi-ROM design but it makes the board
larger, more complicated and draw more power.  With the
current design, I can't have more than 8Mb because I only
have 20 address lines (A0 - A3 from the 16 byte ports and
A4 - A19 are stored in two 8-bit latches).  Sure I could
add one more latch but that's even more to put on the
board.  I know that I can order 27C080's from the States,
but I'd prefer not to if I don't have to.

>Personally, I had toyed with the idea of making an
>EEAROM Drive card several years ago.

If you have built any Apple hardware or have schematics, I
would be interested in seeing them.  I have 4 Apple II
hardware projects on my web site now (one is mine, three
are other individuals).

--
Terence J. Boldt
apple2@cgocable.net
http://www.cgocable.net/~apple2



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