[GTALUG] IBM Mainframe and z/OS

[D. Hugh Redelmeier]

| From: Stewart C. Russell via talk <talk at gtalug.org>

| The printing card punches contained a quite lovely
| device called a code plate that generated the printed dot-matrix
| letters. It's fully described here:
| 
|  http://www.masswerk.at/misc/card-punch-typography/

Thanks.

I never new how the dot matrix was stored.

I did know (i.e. was told firmly) that you risked breaking an IBM 026 by 
duplicating a card with invalid hole combinations.  You could turn off 
printing and that was thought to prevent the problem.

Even then, duplicating a column with too many holes could screw things up 
to the extent that the duplicate wasn't and sometimes the card jammed.

In my experience, an 026 keypunch sounded really bad when you punched a 
column with too many holes.  Much safer to use an 029.

(The 026 was introduced in 1949.  The 029 was introduced in 1964, along 
with EBCDIC and the IBM/360.  You can imagine how much nicer the 029 was. 
But neither had a backspace key.  Or lower case letters.)