> On Jan 27, 2023, at 11:23 AM, Jon Elson via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On 1/26/23 19:13, Paul Koning via cctalk wrote:
>>
>>> On Jan 26, 2023, at 6:29 PM, Chuck Guzis via cctalk <cctalk@classiccmp.org>
>>> wrote:
>>>
>>> I take that back about Versatec, CHM has a document from 1970 on their
>>> electrostatic printer:
>>>
>>> https://www.computerhistory.org/collections/catalog/X163.83A
>>>
>>> I know that Lawrence Livermore had one and used it quite a bit back in
>>> the day.
>>>
>>> --Chuck
>> I worked with one of those on the PLATO system in 1976, where it was used in
>> bitmap graphics mode to print music scores. That at first worked very badly
>> because the paper transport was chain driven, with enough slack in the
>> drive that if you'd stop and start it, you'd get irregular paper feeding
>> with as a result gaps in the graphics. I fixed this by writing a new driver
>> that was designed to stream, so it would never stop in mid-job.
> Interesting. I maintained a bunch of Versatec 1200A printers at work, and
> ended up with a couple of them at home. horrible paper, like a dirty
> chalkboard, smelly toner, if the paper was handled before it dried the toner
> could come off on your hands, etc. But, I had never seen the issue with gaps
> in graphics, and our drivers, especially on the Nat Semi 16032 system was
> VERY slow in graphics mode.
Perhaps it was misalignment, or maybe a different model. I definitely remember
the chain drive, and the play it had, and the defective printout. The solution
was to run in "streaming mode" -- non-stop data. Hard to do given that the
mainframe ran a bunch of high priority real time jobs: the PLATO components.
Solution: do the entire job in a peripheral processor, using the CPU only to
provide an I/O buffer area for reading the file being printed.
I remember the funny paper, not so much the smelly toner. It wasn't as bad as
the screen capture printer we had one floor down, made (I think) by Varian --
it somehow captured the image on the orange dot plasma panel display using
strange paper and nasty liquid toner. The process used is a mystery to me; it
had to be some optical magic because you can't, as far as I know, read out the
state of a PLATO terminal plasma panel electronically. Those panels are
bistable, the pixels are actual memory cells, but I can't think of a way to
sense electrically whether one is on or off.
> When laser printers came out, I was VERRRY glad to move into the future!
>
> Jon
Definitely.
paul
