Amiga Collections: Taifun/Taifun 040 (1987-11-15)(Ossowski, Stefan)(DE)(PD).zip/Taifun 040 (1987-11-15)(Ossowski, Stefan)(DE)(PD).adf/SimCPM/simcpm.doc

Text File | 1989-01-18 | 8KB | 159 lines

                 SIMCPM - a CP/M simulator for the Amiga

                     by Jim Cathey and Charlie Gibbs

                    Version 1.00 - September 15, 1987


     This is a FREELY-DISTRIBUTABLE program.  Spread it around all you like,
just don't sell it, and please keep the entire package (including this file)
intact.  If you find any bugs or make any changes, please let me know - I'd
like to keep my copy up to date.

     This program is based on an article by Jim Cathey which ran in Dr. Dobb's
Journal from January to March 1986.  The original program emulated an 8080,
including CP/M BIOS and BDOS calls, on a CP/M-68K system.  I have modified the
operating system interface to run under AmigaDOS (from the CLI only).

     Note that the simulation is of an 8080, not a Z80.  However, the Z80
instructions LDIR, LDDR, and CPIR have been supported.  This is because the
setting of the carry flag is more like the Z80 than the 8080, and might fool
such packages as BDS C, which would then try to use these instructions.  If
there is enough interest, I could be persuaded to add full Z80 support.

     The IN, OUT, EI, and DI instructions are currently ignored.

     The following BDOS calls are not supported:

          3 - reader input
          4 - punch output
         17 - search for first file
         18 - search for next file
         24 - get active drive map
         all above 26 except random read (33) and random write (34)

     The only BIOS calls supported are those for program termination and
console and list I/O.  (Low-level disk access could get scary.)  If a
program attempts to use an unsupported BIOS or BDOS call, an appropriate
error message will be displayed, along with a register dump, and the program
will be terminated.

     Basic H19 terminal emulation (similar to a VT52) has been provided.
Escape sequences for cursor positioning, cursor to home, screen clearing,
and insert and delete modes are translated to the corresponding Amiga
sequences.  The program MANDOG.COM, which I wrote for my original CP/M
(H19) system and copied here unchanged, demonstrates the cursor addressing
capabilities of SIMCPM.  Any escape sequences that SIMCPM can't recognize
are passed through unchanged.  You can disable all escape sequence trans-
lation by changing the equated value "h19" (in SIMCPM1.ASM) to from 1 to 0.

     To speed up console output for programs which write one character at a
time, I have included a buffered output option.  If you include the -b switch
as the first command-line parameter, all console output will be held until one
of the following events occurs:

          - a carriage return, line feed, or bell character is written
          - the buffer (currently 2K) becomes full
          - a BIOS or BDOS call other than console output is made.

It should be possible to use buffered output in just about any program.
Note that if a program uses the "console output string" function (BDOS
call 9), the entire string is written in a single operation even when
buffering is not requested.

     List output is sent to PRT:RAW.  This ensures that no newline translation
will take place.  The printer is not opened until the first attempt is made to
access it.  If the printer cannot be opened for any reason, the program will be
terminated.  At program termination the printer will be closed if it was used.

     If SIMCPM is brought up with no command-line parameters, it will present
the standard CP/M A> prompt.  At this point you can run CP/M .COM files just
like on a normal CP/M system.  The command line will be scanned for up to two
FCBs and the tail will be passed to the program.  When the program terminates,
the A> prompt will be re-displayed.  To return to AmigaDOS, enter a control-C
(CP/M warm boot) at the A> prompt.

     If command-line parameters are given, they will be passed to SIMCPM as if
they had been entered at the A> prompt.  When the program terminates, SIMCPM
will automatically return to AmigaDOS.  This allows you to run CP/M programs
from an execute file.

     Here are some sample invocations of SIMCPM:

          simcpm
               Loads the simulator, which presents the A> prompt and waits
               for CP/M commands.  Type control-C at the prompt to exit.

          simcpm -b
               Same as above, except console output buffering is used.

          simcpm myprog
               Loads the simulator, which loads and runs the CP/M program
               MYPROG.COM.  When MYPROG terminates, SIMCPM returns to AmigaDOS.

          simcpm mbasic basprog
               Loads the simulator, which loads Microsoft BASIC-80 (if you
               have it), which in turn loads and runs BASPROG.BAS.  When
               BASPROG issues a SYSTEM command, SIMCPM returns to AmigaDOS.

          simcpm -b mbasic basprog
               Same as above, but with console output buffering.  Since
               MBASIC does all console I/O one character at a time, the
               buffered option can speed it up considerably.

     A trace version of the simulator, SIMCPMT, is included.  This program
works like SIMCPM, but it provides optional instruction and BIOS/BDOS tracing.
This is provided as a separate program because it must test whether to trace
each instruction.  As a result, it runs slightly slower than SIMCPM, even when
tracing is not active.

     Before running each program, SIMCPMT will prompt you for starting and
ending addresses for tracing, and whether you want BIOS/BDOS calls traced.
Simulation starts with tracing disabled.  When SIMCPM executes an instruction
at the starting address, tracing is turned on.  All 8080 registers and the
top four stack entries, as well as the current instruction, are displayed
for each instruction until the ending address is reached.  Tracing is then
disabled until the start address is again encountered.  After displaying
8 instructions, execution is suspended; enter G to go ahead with tracing
disabled, Q to quit the program, or any other key to trace the next 8
instructions.

     If you have requested BIOS/BDOS call tracing, the message

          BIOS CALL nn AT aaaa
or
          BDOS CALL nn AT aaaa

will be displayed each time a BIOS or BDOS call is made.  The BDOS call
number (contents of register C in hex) will replace "nn" for BDOS calls,
while BIOS calls will set "nn" to a sequential number starting at 01 for
program termination, 02 for console status, etc.  The address where the
call is made will be taken from the top of the stack and displayed in
place of "aaaa".

     I have included two CP/M programs for demonstration purposes.
TESTPROG.COM is a simple "hello, world" program (try it using SIMCPMT),
while MANDOG.COM demonstrates cursor addressing for an emulated H19 terminal.

     SIMCPM consists of two source modules, SIMCPM1.ASM and SIMCPM2.ASM.
The trace version, SIMCPMT, is made by re-assembling SIMCPM2 and including
the header file SIMCPMT.HDR.  This file includes a definition of the label
"tracehd"; SIMCPM2.ASM checks for this label using an IFD directive, and if
it finds it the trace code is included.  Object modules for both versions
(SIMCPM2.O and SIMCPM2T.O) are included.  The assembler must support an
optional header file and the IFD directive.  No include files are needed,
although AMIGA.LIB is required for linking.  The makefile is set up to use
my own assembler, A68k, and BLink - it should be relatively easy to adapt it
to whatever assembler and linker you are using.  Also, the makefile copies
everything to my work disk as required (I do my actual work in RAM:), and
does everything necessary to create both SIMCPM and SIMCPMT.

     Please address any kudos, flames, etc. to

          Charlie Gibbs
          #21 - 21555 Dewdney Trunk Road
          Maple Ridge, B.C.  V2X 3G6

or to Larry Phillips or Jeff Lydiatt on CompuServe or Usenet.  (I don't have
the time or money to live there myself.)