[GreenKeys] [External] Kleinschmidt 7302 ?

[Jones, Douglas W]

From: Jim Cooper [jim.w2jc at gmail.com] -- Thursday, July 28, 2022 11:42 PM

> As far as printing, it is VERY unique ... there is a
> rotating metal drum BEHIND the paper and a hammer

This is hardly very unique.  About half of the high-speed line printers made in the 1960s and 1970s worked this way.  CDC, Digital. and several other vendors made 300 line-per-minute printers that printed on 132 column paper using one hammer per column and precise timing on the print hammers.  Here's a sample of typical printing from such a printer (in this case, a CDC line printer from 1974):
-- http://homepage.cs.uiowa.edu/~dwjones/plato/DrumPrinter.jpg
Aside: I used that sample to illustrate this web page:
-- http://homepage.cs.uiowa.edu/~dwjones/plato/#printing

The interesting thing from this sample is the poor horizontal alignment of the letters.  The row of dashes across the top illustrates this best.  I would hope that the Kleinschmidt printer did better, but it wasn't nearly as fast a printer, with one moving hammer instead of a row hammers that all try to bang at once to print each line.

The competing approach to high-speed impact printing was one IBM and Data Products preferred.  Instead of a spinning type drum, they had a constantly moving type chain.  On IBMs printers, you could change out the chain to change fonts.  The same array of hammers whacked the ribbon against the paper against the type chain, but the timing was different because of the horizontal scan of the chain past the hammers.

The GE Terminet 600 and competitors used a very similar scheme, except that instead of a type chain, they had a type rubber band, with metal type fingers inserted into the band.  Those were fun because you could use long-nose pliers to pull out the type fingers and move them around if you wanted, for example, to swap the slashed and unslashed versions of O, depending on which one you wanted to be zero and which one you wanted to be oh.  There's a sample of GE Terminet output on the above cited web page as well.

           Doug Jones
           jones at cs.uiowa.edu