Choice Of Modemsdown In The Soho

The Age

Monday May 29, 1995

George Skarbek

I AM considering buying a V.34 modem. If I opt for an internal modem, will the modem answer our personal incoming calls before we have a chance to pick up the receiver?

I would be grateful if you could outline the pros and cons of internal/external modems with the SOHO user in mind.

-- N. Avkiran, Melbourne.

THE MODEM can be instructed not to answer the phone, or to answer after a certain number of rings. This aspect is controlled by the S0 register. Using any communication software, type ATS0=0 and the modem will never answer.

This setting can be programmed into the modem as the default, usually with the &W command, but check with your modem hardware manual. If you wish to receive a fax or have a friend to call you via the modem, type ATS0=2 and the modem will answer after the second ring.

Note that after every command you issue to the modem, you should see an OK on the screen signifying that the command has been accepted.

The pros and cons of internal/external modems is not quite as clear cut. I prefer external modems mainly because faults are much easier to diagnoseand I like to see the activity lights such as RD (receive data) and CD (carrier detect).

At times it is difficult to tell if the problem is at the PC end or the modem. With an external modem, simple tests can be performed to ensure that data is leaving the PC by shorting pins 2 and 3 at the end of the cable and typing characters in the communications program, even a simple one such as Windows Terminal.

If the characters that you type appear on the screen, then you have tested out most of the PC side, as pin 2 is the transmit pin and 3 is the receive pin. This verifies that the com port works and there are no interrupt clashes.

This simple diagnostic test is not possible with an internal modem.

Another advantage is being able to monitor progress via the lights built into the case. Although there are many software packages (comprising memory resident programs) that simulate these and other signal lights, my preference is for the real thing so that you don't waste valuable memory resources.

When monitoring an external modem, if the data stops coming it may be because the other end is busy, the network is saturated due to Internet traffic, your PC has locked up, or the carrier is lost (which means the other end has hung up).

A quick glance to the modem will confirm if you have a carrier, and if you haven't there is no point in hitting ``Enter" and waiting.

If you are getting a lot of spurious characters then it may be line noise of a faulty modem.

It is much easier to take the modem to another site than to take the computer as well.

Now for the disadvantages of an external modem. They cost more. They take up extra desk space and need a power point. And, if you travel a lot and need a modem, there is additional hardware to carry with the computer.

Ultimately, it is your choice based on the way you operate.

8-BIT IDE CONTROLLERS.

Can I obtain an IDE controller to put a 40MB disk into an old XT? I wish to replace an old MFM 20MB hard disk. -- L. Rosenthal.

THERE are almost no 8-bit IDE controllers available. There was one made for specific Seagate drives but I am not aware of any others being available.

If you would like your questions answered, fax them to George Skarbek on (03) 601 2960 or write to him care of Computer Age, 250 Spencer Street, Melbourne, 3000. He can also be contacted via the Internet as gskarbek @melbpc.org.au but please be aware that due to the volume of inquiries it may not possible to reply individually.

Your telephone number will increase the probability of a reply.