Replacment for INS1771 FD controller

[Chuck Guzis]

On 4/29/2006 at 5:53 PM Roy J. Tellason wrote:

>My understanding of these parts is that the 179x series had the data
>separator 
>on-chip,  while the 177x parts had to have a separate chip for the
>purpose...

Not really--the 279x and the 1770/1772 had on-chip data separators (well,
so did the 1771, but you didn't want to use it if you expected to function
in the real world).  179x used either a 1691-type data separator, a 9216.
or a user-supplied one and never made any bones about not having an on-chip
one (i.e. there's no XTDS/ pin on a 179x).

Back to the TRS-80.  I do recall that some versions of TRSDOS used data
address mark FA as a directory sector marker, but there are patches to
TRSDOS that will use only the F8 mark that later systems used.  See Tim
Mann's page on the subject:

http://www.tim-mann.org/trs80faq.html#[13]

And, of course, if you only want to run CP/M on your TRS-80, it don't make
no nevermind anyhow.

Cheers,
Chuck