Hiway DMA card for cable lengths up to 20,000 ft, 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(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 (S2,S3)
        _     _     _     _     _     _     _     _
       | |   | |   | |   | |   | |   | |   | |   | |
       | |   | |   | |   | |   | |   | |   | |   | |
 Delay |_|   |_|   |_|   |_|   |_|   |_|  |_|   |_|
 msec   32    16    8     4     2     1    1/2   1/4