Date   : Mon, 04 May 2009 12:45:26 +0100
From   : mike@... (Mike Tomlinson)
Subject: ADFS 1.53 patch

In article <d8834d20905040224y1d6274a7w68a33600b6bb573@...>,
Alex Taylor <zeem.uk@...> writes

>Are you thinking of XTA (sometimes called XT-IDE) and ATA (otherwise
>known as IDE) disks? XTA is an 8-bit subset of the 16-bit ATA
>interface, and the two aren't interchangeable.

Yes.  I remember years ago using Seagate drives that had a jumper that
could switch them between 8-bit and 16-bit mode, so you could use them
on AT machines (16-bit slots) or XT machines (8-bit slots).

One such model is/was Seagate ST351A/X, e.g. 

  http://support.dell.com/support/edocs/dta/18814/00000003.htm

I originally wrote "Obviously, you lost half the capacity in 8-bit
mode", but the above suggests that the designed capacity (42MB) is still
fully available in 8-bit mode, so perhaps the drive controller used a
double-transfer technique to make use of the full capacity.

The Connor drive I referred to earlier has a jumper to select ATA or IDE
mode.  I thought that might be a 16-bit/8-bit selector, hence the
possible interest to people using IDE interfaces on 8b-bit systems, but
some more googling suggests that this jumper had a different purpose.

> I've got a couple of
>Western Digital 30MB FileCards with duff XTA drives on them, pulled
>out of Amstrad PC1640s.

Are they dead?  Have you tried reformatting them?  You can jump into the
controller BIOS/formatting program by booting a DOS floppy, running
debug, then entering g=c800:5 (if that doesn't work, try cc00:5)

>I think XTA's just an historical curiosity, even in terms of
>connecting hard drives to 8-bit machines. I don't think there was ever
>a great deal of drives made. Nowadays they're like hen's teeth, and
>most of those left are probably broken.

agreed:-)

>I don't think the Conner CFS210A is 8/16-bit configurable, looking at
>the specs and jumper layout.

Agreed.  I mistook the ATA/IDE selection jumper for a 16/8 bit jumper.
Thanks for the correction.

-- 
(\__/)   
(='.'=)  Bunny says Windows 7 is Vi$ta reloaded.
(")_(")  http://imgs.xkcd.com/comics/windows_7.png