On Wed, 15 Feb 2006, Richard wrote:
Based on posts here and information at
hpmuseum.net,
it seems that the
2647A and 2649A had a programmable aspect to the equipment, while the
other 264x terminals did not.
Each 264x terminal is programmable. You can write your own machine code
and load it either from remote or from the tape drive into memory and
execute it. There are several games for these terminals that run on the
builtin processor, for both the i8008 (e.g. HP2644) and the i8080 (e.g.
HP2645/48).
The system calls are well documented in the technical manuals, as well as
all ROM entry points, variables etc. I have about four or five *thick*
binders for the HP2648 with detailed technical descriptions, microcode
listings and schematics for all options that were available.
Christian