Proposed Instructions on the GE 635 for List Processing and Push Down Stacks

Abstract

The instructions that transmit data between the index registers and the memory work only on the left half (address) portion of memory. These instructions are LDXn (load index n from address of storage word). And STXn (store the contents of index n in address of storage word). The effective address of both of these instructions includes modification by index registers. A corresponding set of instructions for transmitting data to or from the right half of memory would facilitate list structure operations. The present order code makes it impossible to so list-chaining operations (car or cdr) without disturbing the A or Q registers.