THE Microdrive for the Spectrum has finally been introduced, more than a year after it was first announced. The specifications of the final version bear a close resemblance to those given originally with the addition of the interface.

NIGEL SEARLE "Praying for the success of the Microdrive."

The expansion module is a black sloping box which fits under the Spectrum and can take up to eight drives. It will cost £49.95 but only £29.95 if bought with a Microdrive, each of which will cost £49.95. Each of the drives has a capacity for at least 85K, so the total on-line memory capacity is approximately 700K.

The Microdrives are controlled by an 8K ROM, the software for which was designed by Dr Ian Logan.

As well as giving control over the drives, the ROM will allow an extended command mode which will enable users to add commands to Sinclair Basic. The extra commands would then be available with the rest of the Basic commands when the expansion module is in place.

The 8K ROM will also correct bugs in the Basic and operating system of the Spectrum by overwriting the errors while it is in operation.

The expansion module allows information to be accessed from the tape drives in three seconds. That is slightly better than the original Sinclair specification, which gives 3.5 seconds as the access time for 16K of memory.

At first the company will be offering the Microdrives exclusively through mail order to the first 1,000 people who bought the Spectrum by mail order last year. In that way the company hopes to compensate for the long wait experienced by some of its customers in the past.

It will later be offered to other owners who bought their Spectrums by mail order in strict sequence until that demand had been satisfied. Nigel Searle, managing director, said that he did not know when the drives would go on retail sale as that would depend on the demand and the amount by which production could be increased.