What's an Intel 4040 worth? - test-drb@ccmp.vtda.org

12 Jan 2012

...
     environment.
They were built like tanks. The print head used a patented
   "flexhammer" system, instead of pins the dots were made by leaf springs
   which had their ends bent over and shaped to a little square point. The
   springs were held bent off the paper by solenoids, which de-energised to
   print the dots, whereby the spring would shoot forward against the paper  What
happened wehen the power went off? Presumably all the springs hit
 the paper. Did this mean you could damage the head by moving paper/ribbon
 with the ppwer off? And how did the springs get back to the soenoids when
 the pwwer was turend on again? (were the solenoids powerful enough to
 attract the leaf prings back?) No, as a previous poster mentioned, below the head
was a little rubber 
bladder that pushed the head against the paper when printing, normally 
it would be angled slightly away from the paper. The head ran across the 
paper supported by the usual bearings running against a bar at the 
bottom IIRC, and a solid bar that ran across the paper at the top. I 
seem to remember that many printers of the time supported the top of the 
printhead against a wire, and using a bar instead was said to be a big 
advantage. To print, the head would be pushed against the paper by 
filling the bladder with air. I don't think there was a compressor in 
the printer, IIRC just some sort of solenoid in the bottom of the 
printer pushed against another bladder. The two bladders would have been 
connected with a little tube that moved with the head. My memory is not 
too clear about the details here.

So what would have happened is that all the magnets in the head were 
energised, the bladder was expanded and the head run across the paper 
while working the magnets and springs, at the end of the stroke the 
bladder would be released and the magnets de-energised while the paper 
moved, and the process repeated while the head went back across the 
paper for the next line of dots.

It was quite fast as well. We had the two colour version but used all 
black ribbons which were cheaper, IIRC there was a DIP switch to say 
whether the ribbon was red and black or all black. IIRC the ribbons were 
rather like typewriter ribbons, on reels, and you would have to thread 
the ribbon through the mechanism. The ribbons would come with a pair of 
plastic gloves so that you didn't have to get your fingers dirty.

...
     You would
love one, I'm sure I would if I could find one and if I had  Indeed it appears I
would...

    room for it... Absolutely the nicest printer I
have ever seen.  Hmm.. I think for dot matrix printers that honour has to go to the
 Sanders 12/7 (or maybe the 700) machine. This is a 7 pin dont marrix
 printer that is so well made that some fonts use 8 passes of the
 printhead -- and it is worth doign that. They do things like justifying
 text, lining up columns, etc.
 Ah, but I haven't seen one of those ;-) It sounds quite amazing.

Another nice printer I have come across was a Qume daisywheel printer, 
it was connected to the PDP-11/40 at the department of applied 
electronics at the university, which I used for my master's thesis. They 
had the manual for it, which included the circuit diagrams and technical 
description. Lots of analogue servo mechanisms.

/Jonas