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.

                                      -- Dave

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