26 Jun
2012
26 Jun
'12
2:41 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of David Riley
Sent: 26 June 2012 21:44
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: ST-506/412 to IDE/ATA/SCSI/? adaptor
On Jun 26, 2012, at 1:37 PM, Chuck Guzis wrote:
simple to
On 26 Jun 2012 at 12:49, Dave McGuire wrote:
80MHz
I would think that a bit of analog hardware
could generate the
signals to mimic flux transitions. At that point, the
microcontroller's only high-speed-requiring job would be generating
the encoding, which isn't tough for a fast one.
No analog needed at all (at least not in the pure sense)--the signals
are RS422-differential type that requires some transceivers not
usually part of a modern microcontroller. The control signals are OC
TTL levels, just like a floppy.
Using an 8MHz AVR to generate floppy MFM worked just fine, so an PIC32 or ARM should be up to the job--I'm
using the former, simply
because it's a bit easier.
I might think a PIC32 would be a bit more efficient (depending on the ARM
used); don't most MIPS architectures have a bit more horespower than most
ARM architectures? Mileage may vary, of course.
In any case, having thought on it a bit, it would probably be fairly do the actual data streaming with a very cheap FPGA
(you don't need much
onboard RAM to store a ring buffer of bits for the current cylinder) and a
tiny
micro for housekeeping and loading data between FPGA
and bulk storage.
Store a cylinder back in when the step command comes, perhaps?
With such a setup, you could get away with a very low-performance micro.
The FPGA would likely run about $15 in single quantities.
If anyone is interested in working on such a solution, I may have time to
dedicate to it soon, but I have no hardware which talks MFM or RLL, nor
working drives to compare to. Still, one can do lots without the actual
devices.
- Dave
This is certainly something I want to do too, it has been on my list for
ages, just not started anything. I don't have enough hardware expertise to
do the hardware interfacing, but keen to learn, and have been wondering how
best to do the software (FPGA - no experience of these yet, Raspberry Pi,
something else). Finding the time is the biggest problem though.
Regards
Rob