[GreenKeys] M33 disable printing when punching?

[wa2hwj at att.net]

A 33 TD can run without having the printer/perf operating. The rear distributor
operates as tape runs through, but the printer stays silent (relatively speaking), 
with the mainshaft still turning, etc.
Of course, the machine would have to be wired for "full duplex" so the
TD/keyboard and printer/perf are on their own circuits.


-------------- Original message from "Douglas W. Jones" <jones at cs.uiowa.edu>: -------------- 


> 
> On Aug 20, 2008, at 10:33 AM, Chris Elmquist wrote: 
> 
> > Is there a mod or recommended practice for disabling printing when the 
> > M33's punch is enabled? 
> 
> I recall that Honeywell (or the predecessor of their minicomputer 
> division, CCC -- Computer Control Corporation) must have been concerned 
> about this in the 1960's, because they designed the object code format 
> (the binary format used by assembly output) for the DDP 615 (formerly 
> the CCC 516) so that it was entirely non-printing. As a result, you 
> could read object code paper tapes on a M33 without wasting paper or 
> ribbon. There was plenty of clatter, though. 
> 
> I wish I could remember more about the format, I think they used what 
> would later be designated as the lower-case block of ASCII characters 
> to get 5 bits of data per character, with a few otherwise unused 
> control characters substituted in for rubout and a few other codes 
> they didn't want to trample. 
> 
> During assembly, before printing a line of listing, the assembler would 
> output an XON, object code, and XOF, so the object tape and listing were 
> both output to the M33 at the same time, again, with no nonsense printed 
> in the listing as the binary code went by, just lots of noise. 
> 
> I thought the whole thing was very clever, but it wold have been nicer 
> if there were something analogous to XON XOF to turn on and off the 
> printer as well as the device control characters for the reader and 
> punch. 
> 
> Doug Jones 
> jones at cs.uiowa.edu 
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