Subj : Re: Commodore MPS printer
To   : Dr. What
From : Jim Brain
Date : Mon Nov 13 2023 10:33 am

On 11/11/2023 1:39 PM, Dr. What wrote:
> -=> Mykrowyre wrote to All <=-
>
>   My> The MPS-802 is the same as the 1526.  It's a business class printer
>   My> with "push" tractor feed so that you don't waste a sheet of paper every
>   My> time you load the printer or advance to the next page.  It has tru
>   My> decenders (j, y, g, etc) under the line. It also has a ton of text and
>   My> formatting commands for printing forms and reports.  In stock form it
>   My> isn't supported by most graphics programs (other than GEOS), but you
>   My> can download a graphics rom for free, burn it to a 2764 eprom, and
>   My> replace the original rom.  This retains all original features and adds
>   My> 1525 compatibility so that programs like print shop, etc, all work
>   My> correctly.
>
> By chance, do you know of anyone who is selling that eprom already burnt?
>
>
> ... Live long and prosper... But don't let the IRS know.
> === MultiMail/Linux v0.52

Looks like someone else is looking for it as well:

https://www.lemon64.com/forum/viewtopic.php?t=36718

I don't see the file anywhere either.  I was not aware, and it would be
nice to have

To clarify, while the MPS 802 and 1526 are the same printer (and they
share the same mechanism and case as the CBM 4023 which is IEEE-488 and
for the PET, I do know there are 2 variants.  The difference is in the
print head.  I *think* the 1526 has round dots in the print head, while
the other has square dots.

Having implemented graphics using this printer, I can truly say the
capability is beyond awful.

The 1526/MPS 802 supported a single redefinable character in the stock
firmware. That's not so bad, as one could define the char as 8 bytes of
graphics, print, redefine it, print, lather, rinse, repeat.

What made it bad was the fact that the character could only be defined
once per print line.  Yep, 80 columns of text and 1 slot could be a
graphics char.

That should have made graphics impossible, but the printer also had a
"carriage return without line feed" control character.

Folks can see where this is going, but to finish it out...

The solution to implement graphics on this printer was to:
set a tab variable to 0
print (tab) spaces
define your graphics for position (tab)
print the graphics char
issue a carriage return with no line feed.
increment tab by 1
if tab = 80, issue line feed and work on next 8 lines of graphics.
else, go to beginning of loop

As you can expect, the speed was horrific, and I can only imagine the
wear on the printer, as it printed one char at a time on a line.
Luckily the onboard firmware knew enough to not bring the head all the
way to the left after each return. But, as I recall, it did have to back
up a bit when printing.  Maybe it was to ensure the printhead was
already moving when printing, not sure.  In any case, the printhead
jerked back and forth across the page in little spurts.

It was a shame, as the print quality was miles better than the 1525 and
friends, and it offered 640 dots per line, as opposed to 480 of the
1526. As the previous poster noted, it also had true descenders.  Text
printing was fast and crisp.

Jim

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