uhler Functional changes to the PDP-10 architecture 19830328

This interoffice memorandum from Mike Uhler (L.S.E.G.) to the PDP-10 Architecture Committee List, dated March 28, 1983, addresses functional changes to the PDP-10 architecture.

Uhler notes a past "laxity" in documenting PDP-10 architecture changes, often due to poor meeting minutes or ambiguous specifications. With the hardware design phase of the "Jupiter 11 CPU" (which has aggressive performance goals) about to begin, a stricter policy is needed to ensure functional correctness and meet design objectives.

The initial functional description for the Jupiter 11 will be based on the Processor Reference Manual (AA-H391A-TK with June 1982 update), KCIO version 8 (March 29, 1983), and Uhler's memo on Extended Addressing.

Uhler requests that any other functional changes or corrections to the listed documentation, intended for inclusion in the Jupiter 11 implementation, be submitted to him by 17:00, Friday, April 29, 1983. Submissions must have been reviewed and approved by the PDP-10 Architecture Committee, include a complete functional specification (including normal and exception handling), and ideally, minutes of the discussion.

Changes received after this deadline will be considered on a "case-by-case basis." Uhler emphasizes that due to the extensive hardware support required for performance goals, the cost of making repeated architectural changes later will be "quite high" as hardware is more difficult to modify than microcode.