Re: Did Commodore cheat with the quad density floppies?

Den Tue, 8 Jan 2019 18:32:08 +0100 skrev Gerrit Heitsch
<gerrit@laosinh.s.bawue.de>:
> On 1/8/19 6:19 PM, Mia Magnusson wrote:
> > The questionable thing is really that the lines have pull-up. In
> > Amiga 600, 1200 and 4000 commodore did solve this by instead having
> > pull-down on the interrupt line in the IDE interface. (IDE is
> > basically a stripped down ISA bus with two I/O address spaces
> > decoded to two select lines. The timing and how all signals work is
> > straight forward ISA on IDE).
> 
> I know, back then there were very cheap IDE cards for ISA where they 
> even omitted the bus buffers, effectively the IDE cable was connected 
> directly to the ISA signals.

IIRC I've never seen any ISA IDE cart with buffers! My memory might
serve me really bad though.

> From the software side, IDE behaved like a WD1003.

With some additions, which btw didn't work as expected in some of the
earlier drives.

For example a Connor 5.25" 60MB IDE drive, an option in the Compaq
Deskpro 386/20, reported one sector too much as it had a off-by-one
issue (with sectors obviously counted from 0 in the drive parameter
table, while Conner put 17 instead of 16 there), which made Linux hate
the drive :)

-- 
(\_/) Copy the bunny to your mails to help
(O.o) him achieve world domination.
(> <) Come join the dark side.
/_|_\ We have cookies.