30 May
2000
30 May
'00
10:19 a.m.
>Just as an aside, I recently encountered a
datasheet for the WD 1773 FDC
>(similar to 1770/72). Do you know of any systems in which it was used?
the 1770/1772 was the 1793+8229+glue on one chip.
Wasn't the 1773 a single-chip version of the 1793,
or am I out in Left
The 1773 was the earlier single density controller.
The 1793 was the later DD and SD controller in nearly the same pinout
and basic IO.
Field? The early Tandy controllers that required 12V
were based on the
1793, and weren't the later 5Vonly ones based on the 1773?
No. The tandy used the 1773 and was wired to provice the -5V and +12V
as needed but there were parts that didn't use the -5V (SMC 1773).
The 1793 wanted +12 and +5 though there were 5volty only versions later on.
Allison
30 May
30 May
11:57 a.m.
The 'Shack model 1's had a 1771 and the model 3's had a 1793. These were
nearly pin-compatible, both on a 40-pin footprint and required buffering to
drive the cable. The 1770,1772, and 1773 are 28-pin parts that can drive
the cable directly.
Dick
----- Original Message -----
From: allisonp <allisonp(a)world.std.com>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, May 30, 2000 4:19 PM
Subject: Re: Defining Disk Image Dump Standard
on.
>Just as an
aside, I recently encountered a datasheet for the WD 1773 FDC
>(similar to 1770/72). Do you know of any systems in which it was used?
the 1770/1772 was the 1793+8229+glue on one chip.
Wasn't the 1773 a single-chip version of the
1793, or am I out in Left
The 1773 was the earlier single density controller.
The 1793 was the later DD and SD controller in nearly the same pinout
and basic IO.
Field? The early Tandy controllers that required
12V were based on the
1793, and weren't the later 5Vonly ones based on the 1773?
No. The tandy used the 1773 and was wired to provice the -5V and +12V
as needed but there were parts that didn't use the -5V (SMC 1773).
The 1793 wanted +12 and +5 though there were 5volty only versions later
Allison
12:12 p.m.
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12:39 p.m.
If you wanted to preserve the sense of the data bus, you'd use a 1791, which
also has the inverted data bus. The 1791 and 1793 are otherwise identical.
It's pretty straightforward upgrading a 1771 with a 1791, with the exception
of the write precomp and clock/data separation logic, which has to be
upgraded. I find the SMC9229 a fine solution. It also muxes the clock to
the appropriate harmonic of the 179x clock.
Dick
----- Original Message -----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Tuesday, May 30, 2000 6:12 PM
Subject: Re: Defining Disk Image Dump Standard
>
> The 'Shack model 1's had a 1771 and the model 3's had a 1793. These
were
> nearly pin-compatible, both on a 40-pin footprint
and required buffering
to
One big pin-compatibility difference is that the 1771 had active-low data
pins, and the 1793 had active-high data pins. The 1791, with active-low
data pins, was closer to the 1771, therefore, and was what was used in
the Tandy double density mod.
-tony
8972
days inactive
8972
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allisonp＠world.std.com -
ard＠p850ug1.demon.co.uk -
richard＠idcomm.com