tjt.mit-vax@Mit-Xx@sri-unix (10/22/82)
Date: 19 Oct 1982 07:04:30-EDT Back in May 1981 I installed Jim Gosling's EMACS on a PDP-11/70 (no overlays, but using separate I- and D-space). The distributed version was not very useful since all buffers were kept in main memory. I replaced the buffer modules with a package that manually paged data from a disk file (actually, each buffer was kept as a list of variable length segments; each segment could have a gap in it; this avoided "paging" the entire file in order to move a single gap). At the time, we were still running Version 6, and the program (with some V6-to-V7 write-arounds) just fit on our machine (with no more than about 60 bytes to spare!). Since then our 11/70 has been converted to 2.8BSD, and there are now 1216 bytes left in I-space. I never got around to installing this new buffer package in subsequent releases of Emacs for several reasons: 1) The next several releases appeared to increase the program size of emacs, so it looked unlikely to fit without either removing functionality or using overlays. 2) Only data buffers were "paged" by my changes -- mlisp code still had to be memory resident. Since the macros distributed with emacs were also getting larger and more complicated, this also looked as though it would cramp the system even further. 3) We had finally started to switch our VAX-11/780 to 4BSD instead of VMS, so it was no longer necessary to try and squeeze a large program into a small computer. However, the current pdp-11 system still runs, and is available (as is), subject to Gosling's current distribution policy. Thomas J. Teixeira tjt@mit-vax@mit-xx (or just tjt@mit-xx) harpo!mit-vax!tjt