Re: Mega STe DMA, HD floppy and other hardware issues

Jorge wrote:

Hallvard Tangeraas <inv@xxxxxxxxx> writes:

Do you know if it's possible to modify the hardware so that the computer already "knows" what kind of floppy is used by reading the status of the HD-detect switch?

Yes, it is possible, its a simple TTL signal. But it is not very useful, and probably because of this it was never done.

Again, too bad :-(
But since it's simple, *can* it be done?
I would certainly like for the computer to automatically "know" what kind of disk is inserted.


TOS doesn't change the FDC clock. The FDC clock is automatically changed by the hardware following the HD signal. That's precisely the reason why it is easy to detect the media type, even without any reading or writing to the disk.

I'm not sure I understand.
Are you saying that the clock (8 or 16 Mhz) of the FDC chip (WS-1772/AJAX) is changed, based on which position the HD-detect switch in the floppy drive is at?
I remember messing around with the HD detect switch when I modified the drive for my STe. I never got around to making the HD-module though, but ended up using the same modified Sony drive with my Mega STe, which works fine.
I don't remember the details, but I made a connection from the HD detect switch to pin 2 of the disk drive connector (34 pin Shugart connector). I think this had to do with the HD mode. Is this something that can be used?


And btw, because of this same reason, *every* TOS version (including 1.0) supports HD disks. The only thing that you get with 2.05 and above is built-in support for formatting HD disks. So you need a third party formatter in previous TOS versions.

In my opinion you need third party formatters in any case if you want PC compatible disks that don't take forever to do, but that's beyond the point ;-)


Oh well, if the floppy drive circuitry of the Mega STe can't be modified to automatically know the disk type to be used I guess I can set Ecopy to format HD floppies by default as that's what I'll be using from now on anyway. No more need to hunt down stores that sell DD floppies that cost twice as much as HD floppies, but store half -if you can find them at all!


--
Hallvard
.

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