21 Jan
2023
21 Jan
'23
1:37 p.m.
>>>>> There is also the SMSC USB97CFDC2
floppy usb controller. Al has the
>>>>> datasheet archived on bitsavers:
>>>>>
http://www.bitsavers.org/components/standardMicrosystems/_dataSheets/USB97C…
>>>> also, I found it here;
>>>> https://www.mouser.com/datasheet/2/374/97cfdc2_01-198397.pdf
>>>>> What more could you ask for--legacy floppy interface, external
flash
>>>>> programming...
> A possible minor issue, and/or stupid question, . . . looking at the
> datasheet, it says that it supports 1Mbps, 500 Kbps, 300Kbps, 250Kbps data
> rates.
> 1Mbps is the never-made-it-to-mainstream "2.8M" drive (and NeXT
"4M"
> (unformatted))
> 500 Kbps is "HD" ("1.4M", "1.2M", and 8"DD/MFM)
> 300 Kbps is a "360K" disk in a "1.2M" drive (compensating for the
360RPM)
> 250 Kbps is 5.25" DD/MFM (and also 8" FM/SD)
> For 5.25" FM/SD, don't you also need a 125 Kbps data rate?
> 1) SO, does this mean that it can't handle 5.25" single density (TRS80
> model 1, early Osborne, and many others)?
> 2) It mentions Win98/2000 driver and firmware. Is there also newer
> driver/firmware support?
On Sat, 21 Jan 2023, emanuel stiebler wrote:
Isn't the biggest problem, that it uses the NEC
765 controller, which can't
read a lot of the WD formatted floppies?
The biggest problem that I had with the NEC765 (PC) was the "flash
blindness" - there was a delay after the index pulse before it could read.
Some systems with Western Digital (179x), for a crowded format, such as
Cromemco, would start the first sector too soon after the index pulse.
Often, you could get around that by masking off the index pulse for
reading, either in cable or on FDC board, or even physically taping over
the index hole of the floppy jacket (not for drives that relied on index
pulse to know whether drive was ready)
Unfotunately, in an unsuccessful read, not having index pulse would
confuse the error reporting.
Also, the WD had a real "track read", whereas the NEC's "track
read" was a
multi-sector read. A real track read is handy for disk analysis (I kept a
TRS80M3, with modified copy of Trakcess, handy), and for formats such as
Amiga which were MFM, but without WD/IBM sector headers.
So, I would agree that WD179x would be preferable, using NEC765 simplifies
drivers for using it as the disk controller on PC.
--
Grumpy Ol' Fred cisin(a)xenosoft.com