Re: Dumb EE question

From: Neil Bradley <neil_at_synthcom.com>
Date: Tue Apr 24 2001 - 21:28:10 EDT

> you don't mind a little extra propagation delay and would rather do it in a
> single chip, then you can do this:
> _1| 1/4 \ 4 _____ _____
> A ---|__| 7400 |O--------| 1/4 \ _9| 1/4 \ 8
> 2|_____/ 3 ___| 7400 |O-----|__| 7400 |O-----
> | 5|_____/ 6 10|_____/
> B -------------------

Perfect! THank you thank you thank you....

For those interested, I'm trying to expand the code execution address
size/range of Asteroids Deluxe from 8K to 40K, and I need this part to
allow me to tweak the chip select on a 27512 when the address range is
6000-ffff. Fortunately there's an A15 jumper pad on the board already so I
can enable that to do the A15 decode (whew!), so 8000-ffff accesses
deselect everything else in the system.

The next thing is to hook up something so I can page in vector ROMs... I'm
thinking about using some sort of 8 bit latch or something... Not sure
yet. I'll have to study the schems.

Anyone know of a C compiler for the 6502. ;-)

-->Neil

-------------------------------------------------------------------------------
Neil Bradley Play a song wrong once and it's a mistake.
Synthcom Systems, Inc. Play a song wrong twice and it's Jazz.
ICQ #29402898

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Received on Tue Apr 24 21:36:52 2001

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