LPT ports, another proposal

ken wolff ken_wolff@dragnet.packetcluster.com
Wed, 08 Nov 95 18:37:26 est


     CT originally used two output pins to key a radio as a convenient way 
     to key negative voltage radios. I've decided reclaim the extra pin.
     
     Top Ten Devices tells me that they do not use pin 14 anymore, so pin 
     14 is available.
     
     The program would have two "modes," old and new. Old mode continues to 
     work with existing CW keying circuits and would be the default. New 
     mode requires rework of the LPT connector circuit. In both cases LPT1 
     and LPT2 are nearly identical. Using this scheme you may enable CW 
     keying and DVK keying from either LPT1 or LPT2.
     
     Old Mode Pinouts:
     
     Antenna switch data:  2, 7, 8, 9 (LPT2 has band data for radio2)
     DVK F1-F4:            3, 4, 5, 6
     DVK escape:           16    asserted for 100ms when escape pressed
     CW pullup:            17    asserted always
     CW key:               1     negated on key down
     Radio1/Radio2:        14   (on LPT2 this is audio select per AB6FO)
     
     New mode Pinouts:
     
     Antenna switch data:  2, 7, 8, 9 (LPT2 has band data for radio 2)
     DVK F1-F4:            3, 4, 5, 6
     DVK escape:           1     asserted for 100ms when escape pressed
     PTT:                  16    asserted with PTT
     CW key:               17    asserted on key down
     Radio1/Radio2:        14   (on LPT2 this is audio select per AB6FO)
     
     Send me your comments, please. - Ken K1EA


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