Weirdity with my 8" drive

[Vintage Computer Festival]

On Sun, 1 May 2005, Dave Dunfield wrote:

> It means that ANADISK saw gaps in the sector numbering.
> For example, it might have seen sectors:
>   1 2 3 4 6 7 8 9
> In this case there is a "gap" which is sector #5 missing.

Gee, why can't it just say, "I didn't find sector 5" instead of the
message it gives, which is akin to, "Hey, I did find a sector between
11-20...guess which one?"

> The higher the track, the smaller the "circle" on the disk with the
> data, hence the more densly packed the bits are - which can lead to
> more errors - this is also the area where head alignment etc. can be
> most critical, and worn drives do tend to give more errors on the
> inner tracks.

Makes sense I suppose.

> But it's may also be a incompatibility between the diskette format and
> the PC disk controller (I am assuming this is the 8" drive that you
> have hooked up to a PC).

Yes, 8" drive.  It works fine for the most part.  I can even format a disk
with DOS and write files to it, read them back, etc.

> The PC disk controller cannot handle gaps sizes as small as some
> other systems did - For example, I find that Cromemco disks do not
> read reliably on my PC. The interesting thing is that certain sectors
> consistantly do not read on one PC, while DIFFERENT sector(s) may not
> read reliable on a different PC.

I would sometimes get back different errors from the same disk.

> reliability. One thing I wanted to add to the program was the ability to
> merge multiple images read from different PCs into one to "collect" all
> the sectors.

This would be useful.

> If you format a disk from the PC can you read it back reliably?

Yes.

Thanks for the input.

-- 

Sellam Ismail                                        Vintage Computer Festival
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International Man of Intrigue and Danger                http://www.vintage.org

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