#02 30 сентября 1995

Part 4 - Emulate technical.

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 *  PART 4 - EMULATE TECHNICAL   *
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 TECHNICAL EDITOR'S WELCOME MESSAGE

 Hello,  I'm Phil Reynolds, your technical
editor.

 I  would  like  to  tell you a little bit
about  what  I  would  like to do, as your
technical  editor.  First of all, letters.
Much  of  what  I would like to do for the
magazine  involves answering your letters.
I  don't  mind  whether  they  are on "I'm
having  trouble doing this...", or "How do
I   do  this...",  or  even  requests  for
articles on how to do certain tasks. Think
of me as the Rupert Goodwins of Emulate.

 I  am including for this month's issue an
article  on  how  to convert tapes to work
with emulators, from a PC point of view. I
am  also  including a .TAP file containing
the   latest   version   of  SPECTEST,  my
Spectrum tester, which is fairly good, and
much  faster than the earlier versions (if
any of you ever used those).

 To  get  in  touch with me, for requests,
articles,  and similar, you can e-mail me:
phil@hedgford.demon.co.uk,  or you can fax
articles.  The number is 01543 428082. (If
outside UK, dial international prefix then
44, then the number, omitting first 0)

 Queries  will  only  be  answered  in the
magazine as a general rule.

 HOW   TO   CONVERT  TAPES  TO  WORK  WITH
EMULATORS Written from a PC point of view,
by Phil Reynolds

 Suppose  you  have  a  lot of those truly
great  Spectrum games. They are all stored
on  the  standard  Philips  cassettes. You
want  to  run  them  on  your PC, using an
emulator. How can you do it?

 A  fairly  simple solution which will not
cost  much  money is to use Pedro Gimeno's
emulator  called  SPECTRUM. It is possible
that   you   have   tried   to   read  the
instructions,  only  to discover that they
are in Spanish. Not to worry, the relevant
parts are included here:

 What  you need is a lead with a connector
to  suit  the  EAR  socket  on  your  tape
recorder,  usually a 3.Smm mono jack plug,
on one end and a 25-pin male D-plug on the
other.  The  tip of the jack plug wires to
pin  13,  the  sleeve to pin 25. This lead
connects  to  the LPT1 port on the PC. You
will  also  need  a voltmeter, in order to
test  the  output  voltage  from  the tape
recorder,  which  must not exceed 5 volts,
or  you  may  damage  your PC. Having done
that,  you should be able to load the tape
in   the  same  way  as  on  the  original
Spectrum.  Having  loaded  it,  snap it to
your hard disk.

 Advantages: Cheap, fairly reliable, works
with most standard loader schemes.

 Disadvantages:   Not  suitable  for  128K
games,   snapping  may  affect  randomness
(e.g.  Colossus  Bridge), not suitable for
many   loader   schemes.  Emulator  itself
unstable. Difficult to work with.

 The  alternative is to get the registered
Z80.  In  order to handle tapes with this,
you  will  need  a tape interface. You can
construct this yourself, like I did, using
the  circuit  diagram that comes with Z80,
or  you  can buy one, like I did later on,
from Brian Gaff. This has the advantage of
not  having wires to break, and it is also
two-way.

 Whichever  interface  you  have,  you can
connect  it  to any parallel printer port.
You   need   to   calibrate   it  for  50%
deflection  in  the DIAGRAM program or 128
tape tester.

 The  tape  interface  can be treated just
like  the EAR and MIC ports of a Spectrum.
The  difference  is  that the speaker does
not echo the tape sound.

 Z80  has loader routines that will handle
most  standard  loaders  regardless of the
speed  of  your  machine. For non-standard
loaders, you must do all of the following:

 Set   R-register   emulation   and   LDIR
emulation ON.

 Set  emulation  speed  to  100%:  failing
that, get a tape recorder that runs at the
highest relative speed you can obtain.

 After the standard blocks, switch to REAL
mode until the program is loaded.

 You  can snap a program to the hard disk.
For games in which randomness is affected,
or  those which load levels, provided they
use  a  standard  loader,  you  can  use a
mirror .TAP file. This behaves rather like
a tape.

 You  can,  of  course, try connecting the
tape  recorder to your sound card. This is
not  usually  as  reliable  as the printer
port connection. However, you can sample a
tape  to  a  .VOC file, and use Z80's .VOC
file support, load a non- standard loading
program or levels. This even works on slow
machines.  The  only  problem is that some
samplers  cause  interference,  which will
cause  the  loading  to break. This may be
worth doing with a good quality setup.

 SPECTEST

 SPECTEST is a good test program, designed
to  work with the Spectrum 16K, 48K, 128K,
+2,  and  variants using the Henk de Groot
or  IMC  ROMs or the South American clone,
the  TK95.  It  tests colour (not for 128,
which  includes  a test card in ROM), ROM,
top  32K  RAM  on  48K machines, sound and
joysticks.  It  also  attempts to tell you
the issue number.

 Loading:  Set  up  .TAP  file,  or insert
tape.

 LOAD  ""    will load the program,
which in turn loads data.

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