Hardware Project

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

Thanks to all who e-mailed about their interest in my first major hardware
project for the Apple II.  Special thanks to Dave Wilson for pointing me in
the direction of making it a ProDOS drive.

What's is it?

I decided to make a bootable ROM drive that plugs into any slot in an Apple
II. My original design was to just copy a block of memory on startup from
the card to RAM and execute it.  Now I may make it a bootable ProDOS drive.
It's designed to support up to 512K, but the current prototype is running
with only 32K due to the small prototyping board and since the mess of wires
is getting confusing.

Why make it?

It's the ultimate ego trip for a nerdy Apple II enthusiast.  ;-)  Seriously
I've always wanted a ROM drive since I was 11 when I got my Apple IIe.  It
just seemed like a cool idea that was an all but unobtainable dream.

What's the status?

It wasn't working until this evening.  I replaced the 373 latches with 374
latches since they were being corrupted.  Of course then my enable lines
were inverted.  A quick change of a couple of AND's to NAND's and now it
works.  Working is a relative term.  Data can be read off the card with a
few lines of assembler or BASIC.  Tonight I'll add new code to the EPROM so
it will boot to H.E.R.O by Activision.  :-)

What's left to do?

Write the controlling code for it and squeeze it into 256 bytes.  Make it
work with ProDOS.  Design a PCB so I don't have to have a nest of wires
hanging all over.  Get the PCB's manufactured.  Sell the extras below my
cost to cut my expenses a bit.  The cost of making 10 boards is about $500
Canadian or less plus the EPROM's which are mostly used ones bought from
flea markets.  A few support chips are needed but will run less than $5 per
card.  With used EPROM's, each card should cost me about $60 or so to
produce.

What can you do to help?

I need to know how ProDOS accesses a block device for read and write.  I
know about all the ID and info bytes required in ROM (thanks Dave Wilson),
but what do I need to handle as far as calls from ProDOS to my card?

-- Terence J. Boldt (apple2@cgocable.net)