PA611-P

This document is an Engineering Change Order (ECO) from Digital Equipment Corporation, dated August 1973, concerning the PA611-P Typesetting Punch Control for the PDP-11 Family.

It addresses two main corrections:

1. Correction 1: Rectifies errors found in the UNIBUS connector print (documentation).
2. Problem 2 / Correction 2: Addresses an issue where M7821 modules, replacing M7820 modules, cause pin J1 to float. The solution is to connect pin J1 to BUS NPR L (specifically, adding a wire from A01S2 to B02J1).

Implementation Details:

• This wire addition affects all units equipped with either M7820 or M7821 modules.
• In-plant: All new production units using M7821s are to be immediately retrofitted.

• Field:

  • Units already in the field using M7821s must be retrofitted immediately.
  • Units using M7820s should be retrofitted at their next scheduled preventative maintenance (PM).
  • It is explicitly stated that M7820 modules in the field should not be replaced by M7821s unless the M7820 module fails.

• The estimated time for installation and testing is 0.5 hours, and a kit (F1024) is provided.