8-inch disk drives

From: Andy Holt <andyh_at_andyh-rayleigh.freeserve.co.uk>
Date: Thu Jul 24 00:56:00 2003

Tony wrote
> I am wondering how on earth you can make a disk controller (note, not the
> OS driver software, the physical controller) that works correctly with a
> 9-sector-per-track format, but fails with the 8 sector-per-track version,
> all other parameters being the same. Because that's the only difference
> between the 320K and 360K MS-DOS formats.

Only if you were to make an "intelligent"* controller that was designed to
work as a sort of co-processor with less interaction with the main system.
>
> Similarly, I can't understand how you can make a controller that works
> correcty with a DS disk but fails with the SS version.
>
as above.

However, the FDCs on even the most recent PC motherboards are fully
compatible (well almost, they may be slightly extended) with the original
Intel chip ... as can be shown by running older software on those
motherboards.

* whether this is or is not more "intelligent" from the end-users' PoV
depends entirely on whether said end-user needs the flexibility of a
main-cpu-controlled preipheral. There seem to be few complaints about such
high-level interfaces in (for example) Ethernat cards.

Andy
Received on Thu Jul 24 2003 - 00:56:00 BST