Simtel MSDOS 1992 September/Simtel20_Sept92.cdr/msdos/emulatrs/v2080j88.arc/HISTORY.DOC

Text File | 1988-01-09 | 6KB | 108 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 3 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  other  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 equipment, but not before I took an  unexpected
two  month  vacation  with  two broken heals as  a  result  of  a
climbing accident.

     During  this  time  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  V2080  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  V2080.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