The System360 Model 20 Wasn't As Bad As All That 3883

thread about using custom character sets on a 1403 train lots of snippage everywhere

Not necessarily. If you have a job mix in which 95% of the output requires only the "standard" glyphs (26 alpha, 10 digits, and a few punctuation characters) but the remaining material uses additional ones (for example, the PL-I glyphs) it would be easy to leave the five copies of the basic glyphs alone, but sprinkle the additional glyphs into the remaining slots. Print speed will go down whenever you have print a line containing one or more of the non-basic glyphs, but you get full-speed (1100 lpm) output automagically when the output contains only basic glyphs.

Note that aside from installing the special slugs in the train and loading the UCS buffer with the appropriate 240-byte map, using the special train required no special action or system configuration change.

The 1403-N1-2821 combination maintained a register showing which character positions contained data which had not yet fired a hammer. As soon as the register reported all print line characters to have been printed, the print part of the operation was complete and any carriage movement implied by the CCW opcode was performed. (If the data included a byte whose value was not present in the UCS buffer, the CU would abandon the print line after the train pbutted its index point twice.)

All of which is to note that there were two components to the typical print command: first, zero or more characters are printed, then a linespace or carriage skip was performed. Does anyone know if there was a limit of no more than five instances of a given character in the UCS buffer, or could you calibrate the printer speed by printing (say) the letter "A" (hex C1) on 264 lines after loading all 240 bytes of the UCS buffer with X'C1'? (264 lines is an arbitrary figure; I use it since it's four pages at 6 lpi.)

You could order special slugs with whatever glyph you wanted, but they would be rather expensive. However, there were a reasonbly large number of "standard" RPQ slugs at prices (for that era) which weren't too high. (Recall that a 1416 train leased for ~US$100-month.) We used this at my PPOE before PL-I became common...and everyone could tell when a PL-I program listing was being printed...

Joe Morris