Modem for the ZX Spectrum.
Overview.
(C) 1996 Vladimir stalls
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In this article I will try
to review the currently existing
modem options for Spectrum
(I know) and separated from
are most promising for
my opinion.
________________
Let's start over again. What is a modem? The very name of
the device contains the answer to the question - Modulator
DEModuyator. That is, the modem - Is a device that
for transferring data between
computers via telephone lines. What is it, I think, no need to
explain, - Anyone can understand how convenient to be able
share files, without leaving
from home, but simply by calling
phone. On large computers
modems have long had a great
distribution, and in the world there are many computer
networks, anyone with a modem can call one of the stations
(BBS) or simply a friend with a modem and share files.
____
Later in the article will meet some of the words, perhaps
someone unfamiliar, so at the beginning explain their meaning:
BBS - reduction translates
something like "E-Bulletin
Ad - in fact it
computer with a modem, which
used to exchange information
both with users and with
other BBS. Information can be
be a file (program), and
texts (letter).
Computer network - in effect
union of BBS. Designed for quick and convenient automatic
dissemination of information. Networks can be both commercial
(InterNet), and non-profit (FidoNet,
AmigaNet). Also, the network can be
local (within one
building or even a room) and global (within the country or
covering the whole world).
Bd - baud rate.
One baud equals one bit per second.
SysOp - System Operator -
Chief on BBS'ke people. Watching her work, sets
it, and as much as helping users.
____
How can now the situation with
modems at Sinclair? We begin with
Mother of Peter: A few years
ago in St. Petersburg has sold
Under the name vicomm.
Connects the case to the tape slot machine signals are used
TapeIn, TapeOut, GND, +5 V. To work there
Two versions of the terminal program - under the TR-DOS and
under iS-DOS. Data transfer rate of 600 and
1800 baud. Implemented a protocol X-modem.
In the accompanying paper
explains that such
modem, referred to the electronic
networks and BBS'kah and is described
work terminal program.
However, nothing in this document
does not say that in fact
vicomm is not a modem, it
just a transformer, hung
a certain amount of detalek,
which serve to isolate a
telephone line. Why vicomm
can not be called a modem? Yes, because he is not engaged in
Module tion / demodulation, all the cases assigned to the
program. In addition, this device is not able to recruit
number and the user must
to do so, agree on the beginning of the session vote, then
press the button and hang up, and only then begins to work
program.
Transmit unit
symbols (terminal mode)
no records of protection from interference is not implemented.
Thanks that, when working in terminal
mode when an interference
lines on the screen comes out every possible bredyatina, and
whole chunks of useful information is lost.
You can communicate with both
user with the same unit and with BBS'koy on
which is set ibm'ovsky
vicomm'a option. In this
moment of such BBS'ok in St. Petersburg two
(One of which - ZX-NET has
years affects users disgusting quality
communication, a complete misunderstanding of Russian letters,
and a constant lack Sysop).
So, the pros and cons vicomm.
Pros: Easy to connect;
simplicity of design, which gives
opportunity, without spending any money on
original vicomm, and buying a transformer and a couple of
capacitors, to make it workable analogue.
Cons: Low speed data exchange; inability to recruit
number and establish a connection, complete lack of protection
from interference in the line of transmission of individual
characters.
About the same time with Peter in Moscow began to be sold
modem "Allegro." This device
worth while interest on
20 cheaper than vicomm, handkerchief
held every two and a half
less space, plugged it
on the tire itself skillfully recruit
number and make the connection. Programmatic support is also
was more developed, the rate of
also higher than vicomm, only
completely absent from the terminal mode. Therefore call
could only be friends with a similar unit, as
with modems of other types of "Allegro" can not communicate. In
recent years, from Moscow to hear News that the "Allegro"
otkryvayutya BBS'ki. And as usual Spectrum BBS'ok used with
disk drives. Personally, I am weak can imagine
how to make a full
BBS'ku on the Spectrum, if only because the amount of
information every day passing through the network is so large
that it does not enough for any drive.
Two of my friends, the commercials
in 1993 they brought themselves from Moscow
this unit, and quite happily share each other's programs. So,
for the user "Allegro" undoubtedly more convenient than vicomm,
on because of more advanced designs and initially normal
programmatic support.
However, both these options have one huge and irresistible
MINUS - Custom! And, having
vicomm or Allegro, you anyway
not be able to connect with a huge amount BBS'ok (if
they do not install special hardware support for your
non-standard modem), or with one another, having ibm or Amiga.
Therefore, in my opinion, the most
preferred is the third
option - a connection to the Spectrum standard hayes modem.
Connect a standard or customary ibm'schikam amizhnikam
hayes, you get a sweet opportunity not only to exchange
information with friends, having
similar device, but
call for a huge number of
BBS'ok your city or even
overseas (if a lot of money).
You will not be up all night to break,
making our way through the crowd wanting for one or two
stations that work with your non-standard device and you will
be able to choose a couple of stations (out of hundreds!) for
yourself and get access to the huge mass of information.
Among the huge number of conferences on various topics you
can always choose something
interesting for you, whether it is
beer, women, books, jokes,
Program, automatic number detectors, magic ... or
something else of the many hundreds of topics.
You can find like-minded opponents, make an interesting debate
and learn something new for yourself. And maybe you become an
avid Fidoshnikom who can not imagine a day without fresh
bundles of letters and will be difficult represent - as you
used to lived without all this vast and
iteresneyshego world of electronic
mail addresses, without those friends from whom you are,
perhaps, distant at thousands of miles and never
seen ...
Seller vicomm'a Sergey Usov
as an argument against
hayes'ov said something like: "what's the use in a standard, if
at all these hundreds of BBS, you can only read mail, files,
there are ibm'ovskie.
My answer: The first - about BBS'ki:
currently working and have a file
areas for ZX-Spectrum programs:
BBS MONTEZUMA
(2:5030 / 362)
ZX-Rise BBS
(2:5030 / 178.47)
Dark Dragon Station
(2:5030 / 362.2)
ASN Station
(2:5030 / 362.3)
This is one of those to which I climb, but if seem a little,
the list can easily be increased.
So far we have to suffice.
Second: I absolutely can easily send the person Spectrum
program at ibm. There, he dragged them to the TR-DOS and looked.
Without hayes'a we would not have
Timeout.
____
Now specifically about the hayes.
Hayes modems come in two types -
internal and external. They practically did not differ in
opportunities, only for the price and
connection. In addition,
hayes'ah found interesting
tsifrochki and shaped as letters. such as these:
2400/mnp5/v42b
2400 - is the speed - 2400 baud;
mnp5/v42b - it's error correction and data compression.
Various combinations of these values in the ground and affect
the cost of modems.
Standard speed - 2400
4800, 9600, 14400 and above.
Connected to the Spectrum modems
speeds greater than 14,400 may
original, but hardly justified, the price of domestic 2400/mnp5
/ V42b modem is about $ 20, and at 14,400
- For more than a hundred dollars.
Minutes of the correction and compression
data - a very useful thing.
Correction of errors in practice
means that during transmission
data terminal mode itself
modem (it deals with its "iron"), without the help of your
program will deal with interference in line and not allow a
failure of symbols, and the appearance of unnecessary.
Data compression means that
Again, the modem transmission
blocks will be their packaging, of course, saving this time
transmission.
So I would recommend
buy modems specifically with the protocols, it will cost a few
dollars more, but will save a lot of time
and nerves in relation to noisy lines.
____
So, what do we have?
In St. Petersburg for a year already Sergei
Zonova sold the RS-232 and
terminal program under iSDOS external hayes modem.
Speed data exchange with the port
- Up to 9600 baud. Protocol -
X-modem. Program in general is an exact copy vikommovskoy,
and has the same features plus
dialing. Using a modem protocols pleasantly pleasing to the eye
to the lack of garbage screen and 100% safety of the characters.
However, I am more sympathetic to
option to connect the internal
hayes'a. Why?
First internal modem
is cheaper than external (External
has its own power supply and case, so the price of
it somewhat more expensive).
Second connector
Internal hayes'a do not need
to spend on RS-232 port, so
as an internal modem connected to the computer bus.
Thirdly you are not limited
9600 baud (author shemki
Connection Michael Kondratyev
used US Robotics 14400).
Connecting the internal hayes
will cost you three chips and
slot. Policy support for
it develops, and development of its
depends on the number of people, it
uses. While some people, the program can only essentials. In
the next plans - implementation file
Protocol Z-modem, which is much smarter and more convenient
X-modem'a; and a few other ideas.
________________
Author wiring diagrams and
iS-DOS software support - Michael Kondratyev,
have access to Fido can send him soap on the address
2:5030 / 362.1
The author of this article - Vladimir
Larkov, wishing to complement or
challenge the above can
send soap on 2:5030 / 362.2
In one of the following numbers
ZX-Format to be published
Internal wiring diagram
hayes-modem to the ZX-Spectrum.
With best wishes, Vladimir.
St.-Petersburg, 14-Feb-1996
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