29 Apr
2006
29 Apr
'06
3:20 p.m.
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