Scor­pio News


April–June 1988 – Volume 2. Issue 2.

Page 24 of 35

Here comes the mystery. The normal disks seem perfect. They format faultlessly in anything; the Gemini at 780K per disk using Teac drives, a couple of Walters XTs using NEC drives, the IBM AT with Epson drives, and Walters AT clones with both 80 and 40 track NEC and Mitsubishi drives. Perfect in my anonymous AT clone which uses Korean Ho-Shin drives which appear to be a component for component Teac clone, even down to the positions of the screws securing the front bezel so the fronts are interchangeable with Teac. They even formatted in an old Shugart 48 tpi drive with notoriously low head current which usually refuses to format anything (although it will usually write to pre-formatted disks). They even work well in both the firm’s old Commodore 8096s fitted with the infamously unreliable Commodore modified Micropolis drives.

How about the high capacity disks ? All I can say is the results are variable. All disks format perfectly in the IBM AT with the Epson drives. All but one formatted faultlessly in my clone with the Ho-Shin drives, and the one that failed came up with an inexplicable and undocumented DOS error message. ‘Parameters incompatible’ – remember this was a virgin unformatted disk – so where the parameters came from, I don’t know ! I fixed that one by using a loudspeaker magnet which erased whatever was on the disk, which it read before it tried to formatted the disk. The Teacs in the Gemini couldn’t be tested as they are only ‘normal’ drives with no double data rate ability. The oddballs were the NEC and Mitsubishi drives in the Walters. The Mitsubishi would format most disks most of the time, but occasionally, they would throw out error after error, flagging out anything between 10K and 500K in duff tracks, But the next time you formatted the same disk it would be perfect. The NEC was worse, only about 30% of disks formatted perfectly (and the same disks had worked perfectly in the IBM and my clone), the remainder would throw out anything between 100K and 200K of duff tracks, mainly on side ‘1’. The same disk would be alarmingly variable, one time round it would be 100K of errors, the next time, 200K. The only thing noted was that more times you formatted them, the number of errors on average was less. I suppose if you formatted them enough they’d end up Ok, but I don’t trust these disks in the Walters.

Did I try Mydisk’s 2 for 1 replacement – no I haven’t yet. The disks are Ok in my machine and once formatted seem to read and write Ok in all the others. The errors seem to be only on formatting. I can only guess that the head currents of the drives differ and the disks are a bit marginal on side ‘1’. Sometime I’ll think of someway of proving this. On the other hand perhaps I won’t. The disks seem to work Ok and they are cheap. Would I recommend them ? or will I buy some more ? If you have a genuine IBM AT with Epson drives, I don’t think you’d ever discover anything was amiss, otherwise you could have problems. Yes I think I’ll buy some more.

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