The Goood, Bad And 2.04e
The Age
Tuesday February 16, 1993
THINGS seem to be coming a little unfastened at the headquarters of PKZIP, the popular file compression package from PKWare. We heard about version 2.04c and its bugs (Green Guide 28 January); then there was version 2.04e.
Now one of the Brisbane bulletin board system operators (BBS sysop) has alerted users to the existence of two versions of 2.04e. The archive of this program is always supplied as a compressed file which you ``run" to extract its contents. The ``good" version was PKZ204E.EXE with a size of 196424 bytes and it displayed the message ``Authentic Files Verified! PKW655" when extracted.
The ``bad" one contains the V2P6Z-II virus, which according to Roger Riordan, creator of the VET anti-virus package and the man who named the Michelangelo virus, is relatively benign. One of a family of viruses written by an American virus researcher, Mark Washburn, which have not, until now, been released into the wild, it does nothing more than infect other files, although like most of these things, it's likely to crash an occasional system.
It increases the PKZ204E.EXE file to 196780 bytes, despite an amateurish attempt to shrink it to the same size. This one does not display the verification message when you extract it.
In the meantime, PKWARE has released version 2.04g. This version detects the type of software and memory-resident programs on a PC and disables parts of PKZIP to avoid crashes. To avoid the risk of any viruses, `The Age' has downloaded the shareware version directly from PKWare's US BBS, and placed it on to the Melbourne PC User Group BBS, together with a patch that updates the registered version of release 204c.
My contact at the Pentagon PC User Group (Washington) had not seen any reports of the infected PKZ204E.EXE in the United States. I will continue to use PKZIP 1.10 for a while until the excitement dies down.
It is truly very easy to connect your computer to another over the telephone lines. All you need are a telephone line, modem (MOdulator- DEModulator), communications software and suitable cables.
Austel is the Australian Telecommunications Authority, established on 1 July 1989 to administer the Telecommunications Act 1989 and to look after the interests of users of all telecommunications equipment, including telephones, modems and facsimile machines.
You may choose to buy the cheapest modem you can find, but make sure it has been approved by Austel (or Telecom, if the modem is old). Such modems have an approval number similar to ``AUSTEL PERMIT: A91/37D/0005". If you disregard this requirement, you will contravene the Act. There are penalties for selling and connecting non-approved equipment, up to a fine of $12,000.
Choosing a modem is like choosing a car: there are many models and they all get you from A to B. Assuming that it works as advertised, it will connect your computer to another. But what features must you look for? How can you decipher the marketing jargon?
Modem specifications can be divided into three protocols: modulation, error control and data compression. It is more important for you to understand their roles than to memorise the details. The international standards body with a long French name is better known as the CCITT.
Its recommendations in this field have ``V" designators, such as V.22, V.42bis and so on.
Modulation protocols define the speed and manner in which the computer signals are sent across the telephone lines. Always look at the raw speed figure, not throughput. You will frequently see modem suppliers using the throughput figures to impress you. Speed is measured in bits per second (bps). It is frequently referred to as ``baud" but this is wrong in a technical sense, although many people use that term in speech.
TODAY, I would not recommend the purchase of a 2400 bps (V.22bis) modem because 9600 bps (V.32) and faster modems are becoming affordable. A high-speed model can also operate at lower speeds. If you can afford it, buy a 14400 bps (V.32bis) unit.
Error control is essential to the transfer of data because telephone lines are prone to spurious noise. V.42 and Microcom Networking Protocol (MNP) 2 through 4 are the common protocols. They cause corrupt data to be re-sent until it is correct. These protocols also send the data in an efficient manner, increasing throughput by almost 20 per cent. Error control protocols can be turned on or off through software switches, so you should read the modem literature for details.
Data compression protocols help to improve throughput because the data can be compressed as much as 4:1 on a 9600 bps modem. Hence my Hayes Ultra 96 claims a throughput of 38400 bps. The data compression designators are V.42bis and MNP 5. The reality is that a file that is already compressed with a program such as LHA or PKZIP cannot be further compressed, and can actually get expanded slightly by the use of these protocols. Again, these are options that should be used only when dealing with uncompressed data.
Modems usually come with a power supply and a telephone line cable if they are tabletop models; the little ones designed for laptops often need no external power or computer-to-modem cable. You can also buy an ``internal" model, where the modem is a circuit board that plugs inside your computer.
Internal modems do not have a set of light-emitting diodes (LEDs), which convey the status of each session. I would not buy one for a desktop computer because an internal ``slot" (a socket for accessory cards) is a limited resource. If you have more spare slots than the accessories you plan to buy, then you could choose an internal model.
There are some public domain programs that display the status of internal modems on your screen, so you are not entirely in the dark.
Internal modems are easier to manage than the plug-in variety when it comes to portable computers.
External modems are connected to the ``serial port", a nine-pin or 25-pin ``male" socket on your computer (a male plug or socket has visible pins; a female one has corresponding holes). Many IBM-PC or similar computers have two serial ports, designated COM1 and COM2. If your mouse needs to be plugged into a serial port, give it COM1. Even if you don't have a serial mouse (as opposed to a bus mouse, which plugs into its own special socket), give COM2 to your modem, for better performance.
Be sure to buy a ``modem cable" when you buy a desktop modem. They are usually separately priced items. I use one that has both nine- and 25-pin plugs at each end, although desktop modems tend to have a 25- pin female socket.
Communications software enables you to dial into a remote computer and reach a bulletin board system (BBS), on-line services such as CompuServe and MCI Mail, or others. It configures your modem and can store everything you see on the screen into a log file. The latter is useful. Some of the following software packages will be reviewed in later issues: Procomm, Telemate, Telix, Qmodem Pro, Crosstalk, Microphone, ZTerm and others.
Many of the popular communications packages are available as shareware. That means you can get a copy for about $5 from a user group or shareware vendor, but you must pay the registration fee to the author separately if you choose to use it regularly. Some shareware vendors sell the registered version, often with a printed manual.
A previous article mentioned a commercial service that provides e-mail and Usenet feeds but its phone number was accidentally omitted.
Connect.com.au can be reached by voice at (03)5282239.
© 1993 The Age
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