Teleprint 390

Paul Koning pkoning at
Wed Jul 13 14:30:30 CDT 2005

>>>>> "Jim" == Jim Beacon <jim at> writes:

 Jim> My 11/45 has a seperate "Paper Tape Advance" output on the
 Jim> console serial interface, whic is set by writing to a register -
 Jim> I assume that the Teleprint 390 / ASR33 has either a solenoid
 Jim> drive or a clutch that allows the tape to advance one character
 Jim> at a time, under processor control.

Bit 0 in the receive control register, right?  That's supposed to be
the papertape reader "reader run" signal.  It isn't used as a one
character at a time thing; it is read/write and if set remains set
until explicitly cleared.

The idea is that the system would accept interactive input by leaving
this bit clear, but then when you told it to read a papertape it would
set the bit.  That starts the tape.  The program would then see
characters streaming in.  At some point (perhaps when it sees a string
of nulls, or when it knows the tape is finished by some internal
coding) it would clear reader run again.

I don't know if this actually was used much.  The ASR33s I remember
rarely if ever had this hooked up; the reader run control was done by
flipping the papertape reader switch on the machine.

I tried to find some code for it, but RSTS dropped the code in V9.6
and that's the oldest I have...


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