Microwriter MW4 help

John S john_a_s2004 at hotmail.com
Sat Oct 9 14:46:53 CDT 2010


John S <john_a_s2004 at hotmail.com> wrote:
>>> 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've finally made an adapter to read the 2564 on my 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:


The file looks OK, but there are a lot of FF bytes on the ROM, which hopefully imply 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.

>I might try and disassemble the code too 

Not yet tried DASMx <http://myweb.tiscali.co.uk/pclare/DASMx/> (thanks for the link Phil), maybe one day.


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