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EPROMs

Posted: Mon Feb 26, 2007 12:51 pm
by Personable85
I was toying with the idea of burning some of my favorite utilities like Supermon onto a chip for easier access. Can anyone tell me how I should go about doing this? What will I need? Is there a good book or wedsite I can reference? Is there someone who can burn the programs for me? This would be for the PETs. Any help would be greatly appreciated! Thanks!

Mark

Posted: Fri Mar 02, 2007 8:26 pm
by j1mt3hcop13rwr3nch
Hi Mark. three hurdles to overcome and I can do two.

The ROM sockets meant to take the 2332 will accept a 2732 eprom with a bit of massaging. Pin 18 and 21 need to swap places between the EPROM and the board, and what to do with pin 20 seems to differ with different boards (On one particular 2001 board I've seen 20 hard wired high but on the schemmy's it's selectable - on that particular board I wired 18 and 20 together.

Note these numbers are at the IC not the socket - bend the pins out parallel to the eprom to miss the sockets and make connections directly to the eprom.

There are lots of plated through holes on the board to connect to so you don't have to spaghetti right at the socket.

Also note that with these 3 pins not making connection at the socket that all sockets are equal. your connections determine the socket address.

Like this: Image

I can do the burn for you too.

So it's just about the contents 8)

Not sure the best way to do it - or if you're limited to a certain course of action - someone else will have to address that - and I'm very interested too.

I'm not sure if you can run an ml program "up there" in rom or if the entire dump will have to be moved down into RAM as an actual part of the program. None of the rom are 'locked out" in BASIC - ie: you can put something there and PEEK it...

I'd be interested in knowing if a small routine could be written so that the ml challenged could write in basic and the resulting dump be usefully compiled and edited so it could be burned, installed, and called with an SYS

EPROMS (PET)

Posted: Sat Mar 10, 2007 11:07 pm
by racob
HI ...I am new here in this forum..but it is becoming so interesting going thru the discussions..

From what concurred in the discussion (and may have missed it before), is there a way to replace the ROMS sets with one or two eproms only (meaning - burn the whole rom set on a 2332 eprom and plug it in (of course with some wiring moifications)..I really like to give this a try.
Also, in the old chicklet unit, I wonder if there is a way to interface a small board (ala-cartridge) to contain and run the programs from...so I can just leave the cassette player just for ornamental purposes..

Posted: Sun Mar 11, 2007 1:54 am
by j1mt3hcop13rwr3nch
is there a way to replace the ROMS sets with one or two eproms only
Yes.
meaning - burn the whole rom set on a 2332
No. 2332's are only 4K.

You could burn the entire ROM set onto one physical EPROM quite easily, using the outputs from the 74154 (all boards IIRC) to simply select "blocks" via address pins higher than A11. Truth is though, there's nothing to be gained by doing so on an existing board. You'd have to fashion a "piggyback" board anyway because the smallest EPROM that could accomodate the 14K required to house basic 4 and the editor ROM is a 28 pin device. This crossed my mind recently when I considered redoing the entire PET board artwork to utilize "modern" components. Man would it get smaller! Still using the 65xx set but a single EPROM replacing all roms and a single SRAM replacing main RAM and doing away with refreshing. I know the purists will cringe, but it'd still be a "real" PET - not an emulator. Keep in mind, that just because you "clear" a socket doesn't mean you can use it though, it's address will still be "taken". So burning basic 4 to a 27128 doesn't really get you anywhere except a small reduction - and we're talking small - in regulator load.

Re: EPROMs

Posted: Wed Apr 27, 2011 1:05 am
by heidy678
nice post and very informative