Re: How to transform a Disk II card to handle 13-sec?

[Linards Ticmanis <ticmanis@gmx.de>]

On 02/10/2011 09:02 PM, David Empson wrote:

> The 16-sector logic state sequencer can definitely read 13-sector disks
> (as evidenced by tools like MUFFIN/CONVERT13/BOOT13 included on DOS 3.3
> system disks).
> 
> I don't recall whether it has any issues writing in 13-sector format,
> such as different timing tolerances which might cause issues if the disk
> was subsequently read on a standard 13-sector controller.

As far as I remember, the "write" part of the two sequencer PROMs is
identical, only the "read" part is different. So writing is not a
problem either. Look at some games from 1980/81 that use "dual booting"
(with two sectors 0 on track 0) to run on both controller types and use
a (possibly modified) 13-sector format for the rest of the disk. For
example the original release of Ultima I. It has no problems writing its
save-game disk on a 16-controller format.

-- 
Linards Ticmanis