LAP6-DIAL was the assembler development environment for
the PDP-12. I used it at
the University of Exeter
between 1970 and 1972. This page collects some of my own experience and also information
available elsewhere on the web.
The acronym was redundant. It expanded to “Language Assembly Program 6 Display Interactive
Assembly Language”, narrowly missing the opportunity to become a palindrome. For the day
the important thing was that it took advantage of the PDP-12's built-in CRT display and was
thus an early example of a display editor. Most other small computers used
a Teletype as an input device.
Unfortunately, the editor was closely coupled to the assembly language syntax. By default
input on a new line started at column 9, the beginning of the op code field in LAP-III (the
assembler proper). A label started in column 1 and was delimited by a trailing comma, so
entering a comma slid everything left to the beginning of the the line. Similarly, a slash
initiated a comment, so entering a slash moved the slash itself and the cursor to column 25.
This was convenient for writing assembler programs, and a pain in the arse for anything
else.
Other links
