Thoughts on a datascope

This might take a lower-level approach, because a simple thing like a different number of sectors or a different sector size will make the drive totally unreadable under DOS, or any other OS that doesn't use the same sector count and size. If you are brave enough to write some code to attempt to read a drive with different sector and gap sizes (those are programmable on a WD HDC, and most others) you might be able to recognize what's been done on your datascope's drive. I'd recommend you consider hard-wiring the write-gate to the disabled state on your HDD while you're trying to read/sample its contents. The WD HDC was very widely used, but not universal. SMC made a pretty good MFM HDC that was not compatible with the WD, as did ADAPTEC and others. The differences were mainly in address mark-related circuitry, but that's enough to foul up readability. IIRC, (somewhat of a stretch, BTW) you're pretty familiar with the CATWEASEL FD interface. A similar approach, with a sample rate that's a harmonic of the nominal data rate will enable you to acquire the data stored on your drive. Unfortunately, writing it back will require you reimpose the precompensation, since that's lost in the recovery process. You can use any controller you've got to move the heads around and to detect the INDEX pulse, however, so you don't have to build a whole controller. You just need code to step the head stack from track to track, switch the heads, and record the signal sampled from the read data line. Timing won't be critical beyond the business of getting the sampled data into a RAM. Since I don't know what the hardware on the CATWEASEL is, I don't know whether it is reasonable to consider using a faster (10x or so) crystal oscillator, but something on the order of 30-40 MHz might be worth a try if it looks like the logic is fast enough to get the job done. At precisely 10x the original rate, the software might even work without modification, and I seem to recall someone telling me that the sample rate isn't that critical. Who knows ... it might even work! Dick ----- Original Message ----- From: "Bruce Lane" <kyrrin(a)bluefeathertech.com> To: <classiccmp(a)classiccmp.org> Sent: Saturday, July 14, 2001 8:53 AM Subject: RE: Thoughts on a datascope drive's format was entirely dependent on what chip the controller was using. If the controller in the datascope isn't using the same chip as in, say, a WD1003, 1006, or other controller, I'm pretty much screwed. on the thing. It's certainly from the right era. translate it into step-by-step! DOS batch language, and a tiny bit of shell scripting under AIX. Again, I lack the skill to write something like you describe.