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Re: How do I add firmware to a card?
- Subject: Re: How do I add firmware to a card?
- From: "Michael J. Mahon" <mjmahon@aol.com>
- Date: Wed, 03 Jan 2007 20:22:23 -0800
- In-reply-to: <459b763f$0$38173$c30e37c6@lon-reader.news.telstra.net>
- Newsgroups: comp.sys.apple2
- References: <459b763f$0$38173$c30e37c6@lon-reader.news.telstra.net>
- Reply-to: mjmahon@aol.com
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Tristan Mumford wrote:
On one final note, let's say I wanted to put an EPROM or whatever on the
card for firmware. How much extra work is required to do that for the ][
based design? I'm not really concerned about writing to it etc. Just a
simple thing that will (with correct firmware) work with a PR#n
Since each address line on the Apple peripheral bus can drive 5 LSTTL
loads, you can usually just directly connect an EPROM to the address
and data lines, enable it with /IOSELECT for $Csxx space, and you're
ready to go--no latches needed!
If you want to use more then 256 bytes, then the $C800..$CFFF space
is also available, with the /IOSTROBE enable, but you must also AND
it with a flip-flop that is set by /IOSELECT and cleared by any
reference to $CFFF.
-michael
NadaNet networking for Apple II computers!
Home page: http://members.aol.com/MJMahon/
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