[GreenKeys] model 33 ASR reader/punch units

[Jones, Douglas W]

From: Michael Zahorik [m.zahorik at sbcglobal.net] Sent: Saturday, January 30, 2016 5:11 PM

> Started to look at the reader. I have a separate power supply that mounts under the sub base. It has a number 183087 on the circuit board. My print FS-8 shows that this power unit is for the reader feed magnet. I have a question, The FS-8 print, says the 183087 is for the 'manual' reader and a 183079 is for an 'automatic' reader. What is the difference between the auto and manual readers. Obviously I must have the manual reader.

The reader supply can be mounted under the sub base, or it can be mounted in otherwise vacant space in the call control unit.  I had to do some sheet metal fabrication to reproduce the mounting hardware used to mount it in the latter position, but the result was nice.  See:
-- http://www.cs.uiowa.edu/~jones/pdp8/UI-8/bugs.shtml#38

The 183079 supply can be used for either reader.  It has an on-board relay to turn reader power off and on.  The 183087 supply does not have this.

The difference between auto and manual readers is whether the reader can be turned on and off by receipt of device control codes from the remote machine (XON, XOFF, if I recall correctly).  Manual readers are entirely manually controlled.

Visually, the difference is in the number of positions in the reader-control lever.  Manual readers just have 3 positions.  Off, on and free.  Auto readers have 4-positions, Free, off, auto and start.

           Doug Jones
           jones at cs.uiowa.edu