-------------------------------------------------------------------------------
Serial GPIB (IEC Bus)
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This is an example capture of some IEC Bus traffic on a CBM 1571 floppy disk
drive.

Details:
https://en.wikipedia.org/wiki/Commodore_bus


Logic analyzer setup
--------------------

The logic analyzer used was a genuine Saleae Logic16 (at 1 MHz):

  Probe       IEC
  ---------------
  0           SRQ
  1           -
  2           ATN
  3           CLK
  4           DATA
  5           RESET


Data
----

The following is happening on the IEC bus in this capture:

 - Controller sets device with GPIB address number 8 to TALK
 - Controller reopens channel 15
 - Device with GPIB address number 8 sends a status string to controller
 - Controller sets the GPIB to UNTALK