The Free On-line Dictionary of Computing (30 December 2018):

CAS 8051 Assembler

   An experimental one-pass assembler for the 8051 with
   C-like syntax by Mark Hopkins.  Most features of a modern
   assembler included except macros (soon to be added).
   Requires an ANSI-C compiler.  Ported to MS-DOS, Ultrix,
   Sun-4.  (July 1993).

   Version 1.2.  Assembler/linker, disassembler, documentation,
   examples.

   (ftp://lyman.pppl.gov/pub/8051/assem),
   (ftp://nic.funet.fi/pub/microprocs/MCS-51/csd4-archive/assem).
   Other software tools and applications
   (ftp://nic.funet.fi/pub/compilers/8051/).

   (1995-01-26)