Hiway DMA card for cable lengths up to 5000ft, processes read and write commands through DMA, and is the card where the box address is set.

This board contains 2 LEDS:
Upper LED – On or blinks for callups to this box
Lower LED – On or blinks for data read/write

Board contains 2 sets of Switch Packs for Polling adjustment(S2,S3) and 1 set for Addressing(S1).

Address Switch Pack
 _     _     _     _     _     _     _     _
| |   | |   | |   | |   | |   | |   | |   | |
| |   | |   | |   | |   | |   | |   | |   | |
|_|   |_|   |_|   |_|   |_|   |_|   |_|   |_|
 P     S     B     16    8     4     2     1
 |     |     |
 |     |     |
 |     |     |__ BA + 32, PIU expansion bit
 |     |         'Set' for PIU with 3 or 4 PCFA's
 |     |         'Reset'  for PIU with 1 or 2 PCFA's
 |     |
 |     |________ Spare, always 'Reset'(0)
 |
 |______________ POLL, normally 'Reset' only 'Set'
 to force PIU to respond to all 
 Hiway polls during adjustment of 
 poll delay time. Reset when adjust
 is complete.

 Poll Adjust Switch Pack
       _     _     _     _     _     _     _     _
      | |   | |   | |   | |   | |   | |   | |   | |
      | |   | |   | |   | |   | |   | |   | |   | |
 Delay|_|   |_|   |_|   |_|   |_| ? |_|   |_|   |_|
 ?sec  16    8     4     2     1    1/2   1/4   1/8