Programmer 7500/MAX_PROGRAMMERS.iso/CLIPPER/MISC/ZRUN321.ZIP/HISTORY.TXT

Text File | 1988-04-02 | 5.3 KB | 100 lines

A quick history of the CPeMulator:


     The original 8080 emulator was  written  on  a  bet  in  1981  that
specified  that  Microsoft  CP/M  Basic  had to be able to run under the
emulator.  The bet further specified that the program had to  be written
in  one week.  The computer used for development was a Lomas 8086 cpu in
a S100 box.  The emulator almost worked, it would blow up after  running
the program or listing it.

     The  8080  emulator was then shelved.  In 1983 I was faced with the
problem  of  converting  a  8080  communications  program to the IBM PC.
After three months of effort I came to the realization  that  the  tools
needed  to  perform the conversion were simply not available for the IBM
yet.  I was faced with either a six month re-write of the  program  from
scratch, or to find another way. The 8080 emulator was the other way.

     The  original 8080 emulator was not usable as it was, but using the
idea behind the emulator I was able to write an emulator specifically to
run  the CP/M program on the IBM PC.  The result was that in one month I
was able to release the program. The communications program  was  called
COPYLINK and was marketed through U.S. Digital.  It came with two files,
COPYLINK.COM which was the emulator, and COPYLINK.OVL which was the 8080
program.  (If  you  were to rename a CP/M MBASIC program to COPYLINK.OVL
and replace the original COPYLINK.OVL file with it you would be able  to
run the CP/M MBASIC program.)  Thus two years later the original bet was
finally resolved.


     In  the  course  of my conversations with people about the COPYLINK
program I found there was an interest in being able to run CP/M programs
on  the  IBM PC  but without having to purchase hardware to do so.  (The
Blue Board was the popular means to do so at the time.)  As a  result of
this  I  took  the time to write a general usage emulator for the IBM PC
which was called the  CPeMulator.   The  CPeMulator  was  also  marketed
through U.S. Digital.

     Later  a  Z80  version  of  the emulator was written to cover those
programs that were Z80 dependent, though it was found that  typical  Z80
CP/M  programs  seemed  to be machine dependent and thus often would not
run on the IBM PC because the expected hardware simply wasn't there.

     The 8080 CPeMulator was used as the basis for the  V2080  emulator.
In  1985 I received a call from a friend about a nifty new part from NEC
that could be plugged in place of the 8088 processor and  could  emulate
8080  code.  I  quickly  rush out and obtained one of the parts, and two
weeks later the V2080 emulator came into existence.


     Having been in contact with other  dealers  and  programmers  as  a
result  of  the  8080  CPeMulator.  I  knew  that I was not the only one
preparing a V20 based 8080 emulator for  the  market.  Recognizing  that
the emulator was really a small market (there were only about six active
companies in the field), it was decided that the program could be better
put to use as advertising.  Thus it was released as a shareware product.

     By  the start of 1986 the computer industry shakeup began to affect
U.S. Digital.  Since I needed to eat, I terminated my relationship  with
U.S. Digital and moved on to there work (helping program a multi-tasking
OS on the 68000 called K-OS for Hawthorne Technology).

     Later in the year, monetary pressures again forced me to move on to
a  higher  paying  position and thus I went to work for Frye Electronics
writing  data  capture and analysis programs for hearing-aid test equip-
ment, but not before I took an unexpected two month  vacation  with  two
broken heals as a result of a climbing accident.

     During this timem U.S. Digital finally succumbed to  its  continued
loss  of  revenue  due to the changing fortunes in the computer software
industry.  In July 1986 the bank foreclosed on  its  loans,  effectively
terminating further business operations by U.S. Digital.  In the ensuing
process of the termination  of U.S. Digital's  business  operations, the
control and rights to the CPeMulator and COPYLINK programs were returned
to me as the author (it took over a year to resolve the legal issues  in
this).

     Since  that  time  I have re-written the CPeMulator to take care of
some of the complaints that have come up.   Several  of  these  included
problems  running  the  program on the Compaq computer (interrupt vector
conflicts), problems with running  the  program  under  debugers  (stack
problems) and the limitations  of the built-in ADM3A terminal  emulation
(solved by removing the terminal emulation entirely).

     I am releasing the new CPeMulator again as a shareware package with
a  few  new  twists  just  to  make  it  interesting.  A new approach to
commercial use of the program being one of  them  which  is  more  fully
described in the Z80CPEM.DOC file.

     I  hope  that you find the new CPeMulator program a useful addition
to your program library and that it provides you with  the  solution  to
your CP/M to MS-DOS problems.


                                                      Sincerely,

                                                      Michael Day
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