Re: need help with identifying some ROMs

On 5/2/22 19:36, groepaz_at_gmx.net wrote:
> Am Montag, 2. Mai 2022, 19:26:11 CEST schrieb Gerrit Heitsch:
>> On 5/2/22 19:00, groepaz_at_gmx.net wrote:
>>> Hy!
>>>
>>> In order to specify better what ROMs come with VICE and/or which the user
>>> needs to provide, i have started renaming them to, and listing them in the
>>> documentation with, their actual part numbers. For some i could not find
>>> them - it would be cool if those of you who own these devices - or know
>>> the part numbers - could provide them. Perhaps you can also point me to
>>> another archive than zimmers (a list of part numbers doesnt really help).
>>>
>>> In particular:
>>>
>>> - mps801.bin (MPS 801 charset)
>>> - mps803.bin (MPS 803 charset)
>>
>> Isn't the MPS803 using a controller with an internal ROM? The controller
>> can use an external ROM, but according to the service manual, that
>> feature is not used and the internal 4K ROM runs the printer.
> 
> Thats what i thought too - however, the .bin that comes with VICE contains 4k
> (3.5k for 803) of charset data. Perhaps the actual internal ROM keeps only
> half of this and the revers mode is done in software? In any case, the part
> number would be interesting :) Perhaps we can have a real dump soonish, see
> https://csdb.dk/forums/?roomid=11&topicid=155739#155808 (That probably means
> the part number is something with 78C11 in it? or did they label them
> differently?)

I remember peeking into my MPS803 back then and vaguely remember that 
there was just 7811 printed on the chip. Maybe there was a part number 
too, but it would have been a much smaller print which I couldn't read.

And I would expect the reverse being done in software. Saves a lot of 
ROM space that can be put to better use. And the code for it should be a 
simple test whether reverse is wanted and then an EOR #$FF (or 
equivalent) on the bit pattern about to be send to the print head.

Looking at the datasheet, it looks like Z80-based controller.

  Gerrit