1990 Era computer room
J. David Bryan
jdbryan at acm.org
Wed Jun 24 11:33:04 CDT 2015
On Tuesday, June 23, 2015 at 22:14, jwsmobile wrote:
> Also I don't recall the Data Products ever scaling as fast by
> restricting columns. At least our 2230, 2260 and 2290 UC only and 96
> character set printers didn't. Got the same speed regardless of the
> columns on those Data Products printers.
The HP 2767A service manual (02767-90002, available from Bitsavers) is a
reprint of the Data Products 2310 service manual. Page 1-17 says:
"The printer receives data from the user system and stores up to 20
characters in the buffer memory. [...] A full line of data is
printed in four zones, each zone having 20 consecutive print
positions. In this manner, the printer's 20 hammer drivers can be
time-shared among the 80 print positions."
...and the spec on page 1-5 says the print rate for the 64-character drum
is 356 lines per minute for 80 columns, 460 lpm for 60 columns, 650 lpm for
40 columns, and 1110 lpm for 20 columns.
I tested a 2767A as a customer of the HP Rockville, MD office in the early
1970s. As I recall, the character set wasn't staggered on the drum, and
the hammer force was constant, regardless of glyph area. The result of
printing a line of hyphens -- or worse, a line of periods -- was a very
loud bang and a neatly perfed page.
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