Wafadrive - 1984
A slightly more rugged alternative was the Rotronics Wafadrive.
This used the same technology as the Microdrive using a an endless tape loop. The unit provided two drives as well as both serial and parallel printer interfaces so you did not need an Interface 1. It offered cartridges in sizes from 16KB up to 128KB. The smaller the tape, the quicker the load and the loop was shorter. Of course, you cannot save a 48KB program onto a 16KB tape!! Timings were slightly longer than for the Microdrive but still incredibly fast compared to cassette tape! Wafas (as they were known) still stretched though the tape did seem more robust.
In terms of cost, Sinclair sold the Interface 1 for £30 and one Microdrive for £50. The 2 drive Wafadrive was £130.
One reason for the performance difference between the Sinclair Microdrives and the Wafadrive was that the Wafadrive operated at two different speeds. When searching for the next area of data, the Wafadrive changed to a higher speed, faster than the Microdrive. Reading or writing data was at the slower speed, in this case, slower than the Microdrive. This did result in slightly more reliable use.
Without doubt, the greatest advantage of either system was the fact that you could save many files to one device and that the software could find the relevant file by itself with no pressing of play or record buttons as was required ona tape recorder.
The disadvantage came from the storage media, an endless tape loop of high quality but very thin tape. Over time, this used to stretch so the index marks were no longer where they should be. Reformatting the wafa or microdrive did return it to working condition though, eventually, the tape would stretch to the point it would break.