Microwriter MW4 help

[John S]

Hi,
 
I have finally made an adapter to read the 2564 ROM from my Microwriter on my EPROM programmer
(which can only read the 2764). There were about 5 pins to rewire, I'll write some notes later on 
the differences.
 
I've upload the ROM image to:
 
http://www.vintagecomputers.btinternet.co.uk/mw4/mw4.zip
 
The file looks OK, but there are a lot of FF bytes on the ROM, which hopefully implies that 
the whole 8K bytes weren't needed rather than the ROM is faulty. Hopefully Tony can compare 
this with his ROM and come back with any further tips or questions. If anyone else has a fully
working MW4 please make contact.

I haven't tried to disassemble the ROM yet (thanks Phil for the link to DASMx), maybe one day.
 
Regards,
John

==================================================================
John S john_a_s2004 at hotmail.com Wed Sep  8 15:40:20 CDT 2010

>> I recently obtained a Microwriter with an LCD display. 
>> 
>> Else it may be faulty
>> I found Tony's post from 2009 asking for a 'good' EPROM image maybe 
>> mine is failing in a similar way.

Tony wrote:
> FWIW, I am still stuck... I am pretty sure the Firmware EPROM in mine is 
> corrupted, some 'chords' do not produce the characters I would expect 

My one can generate all the letters, numbers and punctuation marks so fingers 
crossed the EPROM is OK.

> IIRC, the EPROM is a 25C64 (which is slightly different to the more common 
> 27C64). If you have a programmer capable of reading out that device, it 
> would be interesting to compare the ROM in mine with it.

OK, I'll try and read the EPROM. This might take me some time, but I am keen to 
do it as there is very little technical stuff about the MW4 on line.

I might try and disassemble the code too (but I don't think IDA has a 1802 option!)

Regards,
John