[sebhc] printer driver

Lee Hart leeahart at earthlink.net
Tue Feb 22 15:54:23 CST 2005

>> If I remember it used to calculate the printhead temp by monitoring
>> the resistance of one of the printhead coils?

Yes, that is correct.

Dave Dunfield wrote:
> I do recall the thermal limiting after you had printed a few lines.
> I don't think mine waited "5 to 10" minutes, but I do recall that
> it would go into mode with a few second delay between each line

Also correct. The temperature sensing circuit had two outputs to the
microcomputer; 'warm' and 'hot'. A 'warm' head added a few seconds delay
between lines. A 'hot' head stopped printing entirely until the head
temperature came back down to 'warm'.

The peak printing rate was actually quite high; 165 chars/sec. That was
actually pretty fast in those days.

> anyone have a scan of the H14 manual?

No scans, but I have the original manual. Send me your address offline
and I'd be happy to loan it to you (if you promise to return it).

> My very first printer was a Teletype Model-28, which I generated
> baudot data for by toggleing the interrupt-enable line on my first
> homebuilt 8080 (didn't use interrupts in that system) - now that's
> going a long way back!

Yes indeed! My first printer was a baudot teletype, left over from my
ham radio RTTY work. 60 baud -- now *that* was slow!

I graduated up to a Selectric typewriter with a board to run it as a
printer. 137.5 baud, and another oddball shift/rotate code to deal with.

So, the H14 was actually quite a step up!
Ring the bells that you can ring
Forget your perfect offering
There is a crack in everything
That's how the light gets in
	-- Leonard Cohen, from "Anthem"
Lee A. Hart  814 8th Ave N  Sartell MN 56377  leeahart_at_earthlink.net

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