40-track adaptor

10 Over the past few years, the cost of 5"/4 inch floppy disk drives has gone down to the extent that modern, 80-track, double-sided drives now cost less than a simple, 40-track, single-sided type some three years ago. It is, therefore, not surprising to see many computer owners upgrade their systems with a set of 80-track, slim-line drives to boost the mass storage capacity of their micro. However, 40-track stored programs are not readily retrievable in the new system, because the distance be- tween tracks in the 40-track drive is twice that in the 80-track model. This circuit offers a solution to the problem, in that it doubles the step distance for the R/W head in the 80-track disk drive, so as to make it "look like" a 40-track type to the computer which should, of course, be programmed with a 40-track disk operating system (DOS). It is seen from the circuit diagram 40-track adaptor that Gate Ni receives the FDC con- troller STEP pulse, which is used in the circuit as a timing ...