Engineering Change Order Log - CD11 DMA Card Reader

This document is an Engineering Change Order Log detailing various problems and their corresponding corrections for the CD11 DMA Card Reader, used with the PDP-11 Family of processors. The entries span from May 1972 to October 1973.

The issues addressed fall into two main categories:

1. Documentation Corrections: This includes updating drawing directories, correcting miscellaneous errors in documentation, ensuring wire lists match existing back panels, and adding accessory/software lists and acceptance procedures to the CD11 print set.
2. Hardware/Functional Corrections: Several entries detail significant functional problems with the CD11 unit. These include issues with the "End of File" circuit, unwanted card feeding during processor power cycles, oscillations on the INDEX MARK line causing system crashes, a missing BUS NPR L signal preventing proper interrupt handling, an ineffective BUSY status bit, and timing inaccuracies regarding the validity of card reader data.

Many of these functional corrections involved specific hardware modifications (adding or deleting wires and components) and required immediate retrofit ("Retrofit immediately") for all CD11 units in the field, with estimated installation and test times ranging from 0.5 to 2.0 hours. Some entries also served to correct or clarify details from previous Field Change Order (FCO) supplements.