The Samurai system has two splendid NEC drives and can read both SSSD and DSDD disks. About 20 of my disk bargains were proper DSDD types and I decided to have a go at altering some of the rest from SSSD to DSDD. The technique is quite simple, and, if carried out as described, is unlikely to damage the disk.

With a ruler, mark a point 66mm down from the top edge and 84 mm in from the right hand edge of the disk using a soft pencil. Using a narrow-nosed single hole paper punch (obtainable from good stationers), punch a hole through the upper side of the disk jacket. Take care to avoid punching a hole through the disk itself or creasing it in any way !

Rotate the disk in its jacket so that the index hole appears in the new hole and, using a needle, punch a hole through the centre of the disk index hole and under-side of the disk jacket. Turn the disk over and using the hole punch as before; punch a hole centred on the needle mark on the under-side of the jacket. Finally, place an opaque adhesive sticker over the original index hole and check that the index hole on the disk is not obscured in any way (you may have to do a little trimming). The new hole should lie a little to the right of the original. Some of the disks which I acquired have no write-protect notch but since the 8″ write-protect facility depends upon the notch being uncovered, these disks are not protectable. However, if you punch out a notch on the bottom edge, about 5 mm long and at least 2mm wide, centred exactly 4.4 mm from the right hand end, the write-protect facility is activated.

The disk should format correctly in DSDD mode if your software has been appropriately modified and the drive is designed to do this, but if your disk will not format, check that the new hole is in the right place. If, in spite of your best efforts, the doctored-disk won’t format in double-density, it can usually be formatted as a single-density single-sided disk – just transfer the adhesive patch from the old hole to the new one.

I have modified over 40 disks in this way with only one failure – due to over-enthusiastic use of the hole punch whilst drinking parsnip wine – there’s a moral here somewhere.......

Next Issue

The dates for the next issue of Scorpio News, Volume 2 Issue 3, are as follows:

Letter/​articles in by 01/06/88; adverts in by 08/06/88; newsletter posted to you by 01/07/88.