PL/M is a high-level programming language especially designed to
simplify the task of system programming for the Intel 8-bit family
of microcomputers--the 8008 and the 8080.  The files provided in
this archive contain version 2.0 of Intel's PL/M cross compiler
for the 8080.  The PL/M programming langauge is described in the
Intel publication, 8008 and 8080 PL/M Programming Manual.  A second
Intel publication, 8080 PL/M Compiler Operators Manual, describes
the operation of the PL/M cross compiler.

The Intel 8080 PL/M Cross Compiler is a two pass compiler written
in ANSI FORTRAN.  PASS 1 reads a PL/M source program and converts
it to an intermediate form on work files.  Optionally, a listing of
the input source program may be obtained during this pass.  Errors
in program syntax are detected at this stage, and appropriate error
messages are sent to the list file.  PASS 2 processes the work files
produced by PASS 1, and generates machine code for the MCS-80 CPU.
This machine code, which may be in either BNPF or Hex format, may be
loaded and executed directly on an INTELLEC 8/Mod 80 Microcomputer
Development System, simulated using INTERP/80, a cross-simulator of
the 8080 CPU, or used to program ROMs.  PASS 2 will optionally
produce a symbol table and a mnemonic listing of the generated
machine code. Certain errors may be detected during PASS 2 and are
reported in the list file.

The operation of each pass of the PL/M compiler is governed by a set
of parameters know as compiler controls, each control is identified
by a unique letter of the alphabet.  Each compiler control is provided
with a default value which is used throughout the compilation unless
explicitly altered by the user.  The commonly used compiler controls
are described below and a complete list of compiler controls is given
in Intel's 8080 PL/M Compiler Operators Manual.

The value of the compiler controls may be changed at any time during
PASS 1 or at the beginning of PASS 2 by entering a control record.
Control records must begin with a dollar sign ($) and have the
following form:

     $<id>=<value> [ $<id>=<value> ] ...

where <id> is the unique letter assigned to the compiler control
that is to be changed and <value> is the new value.  Blanks may be
included on either side of the equal sign (=) but not within the
$<id> or <value>.  Two special control record formats are available
to interrogate the current values of the compiler controls.  A
specification like the following:

     $$<id>

will cause the current value of the compiler control represented
by <id> to be listed, while a specification that consists of just
two dollar signs will cause the values of all compiler controls to
be listed.


Control records may be included anywhere within the source input read
by PASS 1 or in one or more input lines terminated with an all blank
or null line to be read at the start of PASS 2.


PASS 1 Compiler Controls

    CONTROL VALUES DEFAULT    USE

       L     1-79     1       Leftmargin.  Specifies the first
                              character position processed on each
                              input line.  All leading characters are
                              ignored.
       P      0,1     1       Echo input if 1, suppress echo if 0.
       R     1-80    80       Rightmargin, ignore trailing characters
                              on each input record.
       W     1-120  120       Maximun number of characters per output
                              line.

PASS 2 Compiler Controls

    CONTROL VALUES DEFAULT    USE

       F      0,1     1       Display decoded memory initialization.
       T      0,1     1       Display cross-reference table of
                              approximate memory address versus
                              source line number.
       H              0       Header.  Decimal address at which
                              generated code should start.  I.e.,
                              the start of the program's ISA.
       M      0,1     1       Display symbol table.
       Q      0,1     1       If 1 then object file is written in
                              BNPF, otherwise the object file is
                              written in Hex format.
       V              0       Page number of first page of the VSA.
                              I.e., variable storage, stack, etc.
                              If set to zero the first availabe page
                              above the ISA is used.