EUG PD


Tape Troubles

 
Published in EUG #7

Tape Troubles

As I recall the early days of home computing (circa 1980) and the appearance of dedicated magazines, it seemed that more column inches of the "Problems Answered" pages were devoted to airing difficulties in using tapes than to any other subject!

Certainly in the early days a number of suppliers of software has not set up acceptable copying systems with the result that their tapes were of varying quality but of course most of them were willing to provide a replacement when a bad copy was received. However, with the increasing market and competition, the quality of tapes improved dramatically. In the twelve or more years since I bought my first tapes from Texas Instruments (for my Texas TI99 - still going strong!) I have only had one bad tape - it had a complete section unrecorded! However, I always shop from reputable suppliers and would not therefore expect a problem.

Alignment Issues

My recollection of the response of the columnists (supposedly experienced in their fields) was that the more "agricultural" your player was the less the likelihood of trouble providing the head alignment was correct. Hence many articles on how to adjust the head of your player.

The computer demands a well defined frequency spectrum and the tape suppliers do their bit to maintain a matching performance. The weak link in the chain is Everyman's player/recorder. If a tape is readable it is most probably that a basic mono recorder will read it successfully. Of course the best system is the dedicated recorder/player e.g. the Acorn Data Recorder No. ALF03. The next best thing is the so-called computer compatible machine - a machine designed for quality playing of audio tapes but having switching to vary its characteristics to those most suited for reading and sending of computer data. An example of this type is the Sanyo DR101. However the LOW-FI audio mono tape recorder that churned out The Beatles is as good as any although you will have to find the best setting for the volume control and if yours is of a slightly more sophisticated variety having a tone control, you have a further knob to twiddle to get the best results. Mark the knobs in some way e.g. Tippex fluid.

I occasionally use for tape copying, a machine I bought many years ago to make correspondence tapes - it is predecimal coinage £9. 19s 6d - Woolworths' Winfield brand. So if you don't have a mono recorder try the car boot sales, church fete etc, set the head alignment and go! Or if you have a walkman or other Hi-Fi/Stereo machine then use it but do not expect to succeed if the tape is not of a standard acceptable to a mono machine (with a correctly aligned head!).

All of the above relates to a commercially supplied tape. If the tape is an amateur recording then the whole business becomes a different ball game!

Worn Tapes

Now, what is a "worn" tape? If information essential to the program and its loading is not on the tape no HI-FI, stereo, all singing and dancing graphically equalised replay system will recreate the missing data. How is the information lost? Firstly, by mechanical means - a crumpled tape (readily seen) or a minute piece of tape coating dislodged (not readily seen). Secondly, by electro magnetic influence - too long in the Underground - stowed near a high wattage loud speaker - magnetic residue from earlier recordings where the tape has been used many times for recording (you may have noticed the background noise on audio tapes for the same reason) - loss of permeability of the coating because of repeated recordings.

You can doubtlessly tolerate the odd bits of sound missing on an audio tape but the computer is rather less accommodating and needs every bit of the original input data if the program is to load and run correctly. Forgive me for restating the obvious! So I feel there is no such beast as a "worn" tape - it is either a loadable or not loadable tape - a complete set of data or an incomplete set of data.

The suggestion of switching between the two adjacent heads (R and L) of a stereo recorder may achieve a compromise with the single track on a loadable tape but the special arrangements proposed (EUG #5) would surely be unnecessary if a 3.5mm stereo/mono adaptor is used between the player and the computer lead (Tandy 274 - 374). I don't understand what is meant by the tape being "badly recorded on one channel". I presume what is meant is that one or other of the heads may have a nearer alignment to the track optimum than the other and thereby receive a stronger signal. If strength of signal is the objective of the arrangement then why not summate the signals which should be of identical characteristics, by use of the adaptor.

Conclusion

The message is whatever player you are using, take care of the head alignment - this is the prime source of success. Finally take great care of your computer tapes - they need much more consideration than your audio tapes.

Thomas Boustead