RE: CBM Printer History /compatibility

From: Marko Mäkelä (
Date: 2001-12-19 09:22:41

This one bounced due to unrecognized sender address.  Very interesting, I
must say?  Konrad, have you come across to any DDR equipment, like
Robotron?  Were there any Polish computers or accessories?

Date: 	Tue, 18 Dec 2001 13:38:12 +0100
From: Konrad =?iso-8859-1?Q?Bury=B3o?= <>
Subject: RE: CBM Printer History /compatibility
In-Reply-To: <D4E26D5DAF38D5118BB900508BAF5E2E1C321D@oeca-ex>

Hi !

At 11:13 01-12-11 +0800, you wrote:
>I'm hoping to write an emulator for both the 1520 (I knew about this
>plotter, have two of them, but no pens) [...]

I don't have a 1520 (here in Poland, I've seen it only once !), but I've 
got a dozen or more of those MCUs (6500/1 ?) that were inside (I've checked 
that chips numbers are correct)...

Once upon a time I found infos from a guy who worked in CSG, and he said it 
was possible to switch that MCU into "emulation mode", in which it dumped 
contents of an internal ROM to one of ports. So it would be possible to 
reverse-engineer the ROM and build a clone of a 1520.
Unfortunately i've lost those infos - but nevertheless they wouldn't be 
useful enough, as I remember they didn't say anything on how to turn this 
mode on. Maybe someone has got any info on that ?  IFAIK Rockwell also made 
those chips - so, maybe it can be found in some older Rockwell databooks.

BTW - I've got a plotter, but it's completely dumb and has only one color. 
It was produced either in Czechoslovakia or in Soviet Union (no, not Czech 
Republic nor Russia - it's from 1989), probably in first - as the text 
written on the top says "Graficka Jednotka XY4140/Laboratroni Pristroje 
Praha", also sticker at the bottom says "Made in Czechoslovakia". But there 
is antother sticker "Hydrometrpribor Sverdlovsk/Made in USSR". What a 
mystery ;-)
This plotter is based on SSI/MSI chips (simple TTLs and CMOS ones - half 
Czech, half Russian) and has a simple interface, consisting of 5 lines: 
Step, +/-, X/Y, Pen UP/DOWN, Home Detect - so I had to implement a line 
drawing algorithm, also circle drawing (both Bresenham ones). All stuff is 
written in our favourite TurboAss ;-)  Then I started studies and had no 
time for more.
I've almost forgot - this plotter is hard as rock, I think Russians used it 
in their army as a weapon ;-)

Nick, can you tell something more about that emulator you are going to write ?


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