Microwriter MW4 help

John S john_a_s2004 at hotmail.com
Tue Oct 12 03:47:11 CDT 2010

Thanks, yes a schematic would be great. Can I post it to the web please?

I'm sure Tony knows the following, included as background.

Here's the adapter I used to read the 2564 in a 2764 programmer:

2564 pins       2764 pins
20 (A11)        23 (A11)
23 (A12)        2 (A12)
2+27(CS1+CS2)   22 (OE)
1 (Vpp)         28 (Vcc)
22 (PD/PGM)     20 (CE)
(NC)            27 (PGM)

All other pins connected straight through. The above can't be always used in the 
reverse direction (eg using a 2764 in a 2564 socket), as CS1 and CS2 may or may not
be tied together depending on the circuit.

Also programming a 2564 uses a different algorithm to programming a 2764. For example,
on a 2764 Vpp can be left at programming voltage of 21V during a verify cycle, whilst on the 2564 Vpp is at 25V for programming and 5V for verifying / reading (I assume the 25C64 is similar but with a lower Vpp).


Tony Duell 
    ard at p850ug1.demon.co.uk

    Mon Oct 11 15:29:35 CDT 2010

> I've finally made an adapter to read the 2564 on my programmer (which can o=
> nly read the 2764). There were about 5 pins to rewire=2C I'll write some no=
> tes later on the differences.
> I've upload the ROM image to:
> http://www.vintagecomputers.btinternet.co.uk/mw4/mw4.zip

THanks. I've downloaded it, it unpacks OK. I wondered why the file was 
larger than ecxpected, but then saw you'd included both hex and binary 

I will probably burn it into a 27C64 (those I have, and my programmer can 
easily handle them) and make an adapter to use it in the MW4. Then we can 
see if that gets mine working.

I won't be doing this just yet (I've gor various other things to do), but 
I will let you know how I get on when I do do it.

If you are going to disassemble the ROM, do you need schematics of the 
MW4 hardware?



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