On Sat, 28 Dec 2013, Tony Duell wrote:
On the modle 1, TRS-DOs wrote the directory track with
one of the
'special' DAMs. As a reasulT the 179x series of controllers cannot
correctly write such a disk. On the M3, TRS-DOS used the 'deleted'
DAM on the directory track. And IIRC LDOS did that on both the M1 and M3.
There used to be a rumor that the specific choices of which DAMs
Randy Cook used for TRS-DOS was directly due to a typo/misprint
of the DAM chart in the 1771 docs.
What id TRS-DOS 2.3B on the M1 do? IIRC it had
compatibility problems
with all older TRS-DOSes (including 2.3). Did it use the 'deleted' DAM
on the directory track? Something tells me it did.
Not familiar with that one. Possibly one that came AFTER the
introduction of the Model 3, specifically intending to provide
a model 1 OS set up for model 3 compatability.
Remember Baron
Von Munchausen's role in the word "bootstrap"!
????
The good Baron was travelling through a swamp when he began to sink
in. There was nothing overhead nor to the sides to grab. So, he
reached down and grabbed the straps of his boots, and pulling,
lifted himself out of the swamp. Hence the verb "to bootstrap"
to refer to the improbably seeming task of an OS loading itself in.
All handled by ROM code to load one sector and do a jump.
Holub once asked my WHY did MS-DOS/PC-DOS need to have
IO.SYS,MSDOS.SYS/IBMBIO.COM,IBMDOS.COM as the first two files on the disk.
It's because DOS can not FIND them otherwise until after those two files
are loaded.
--
Grumpy Ol' Fred cisin at
xenosoft.com