9 Oct
2010
9 Oct
'10
12:46 p.m.
Hi,
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:
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 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.
Regards,
John