17 May
2023
17 May
'23
8:13 p.m.
On Wed, 17 May 2023, Mike Katz wrote:
If you have access to a Gimix SS-50 6809 or 6800
system, Gimix used the
WD1791 in their double density disk controller. That controller can do
single and double density 5 1/2" and 8" disks (250KHz, 500KHz & 1MHz data
rates).
Some NEC 765 controllers, including the original 5150/5160 are hard-wried
to not be able to do single density, and they have a limited range of
data transfer rates.
Other than that, 5170 style controllers can do double density 5.25"
(sorry, there is no 5 1/2" disk), and 8".
The ones that support single density (check Dave Dunfield's site) can do
single and double density 5.25" and 8".
The 1MHz data transfer rate is needed for the 2.8M 3.5".
So, those capabilities are same as many NEC 765 PCs.
But, the WD1791 includes a real TRACK READ! Try that for Amiga!
The NEC 765 design does not have a real TRACK READ; instead, it offers a
multiple sector read.