3 Nov
2013
3 Nov
'13
3:15 a.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of emanuel stiebler
Sent: 03 November 2013 10:33
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Looking for a MicroController Recommedation
On 2013-11-02 18:25, Robert Jarratt wrote:
it
I have been mulling a project to emulate MFM
disks (DEC RD53 and RD54
in
particular) at the disk-to-controller interface. Before anyone asks, I
don't want to interface to Qbus (or any other bus) because I want to
emulate the least possible hardware and keep my RQDX3 cards working.
And yes, I know this has been talked about many times before, but I
want to actually start trying this out.
Pops up every year. Reoccurring subject. And a lot has been written about
on this very list. So just check the archives ...
I'm not innocent either ;-)
I made myself more than two designs already, but never had the time to
write the software for it, or even finish it. At the end, the job came in
between :(
and
My idea is to use some kind of MicroController,
talking to specific
interfacing logic that drives the lines, and using SD memory for the
actual storage. I am considering two approaches:
[..]
What I tried was to simply record the signal from the drive controller, play it back. Like a digital version of analog tape.
some remarks to it, 40 MHz is probably not enough. So you need a nice
controller which can also handle the 4-bit mode of the sd-flashes.
What frequency do you think is needed? According to the RD53 manual the
pulse width is 50ns.
check the write-precompensation chapters on disk drives. Some headaches
are hiding there.
Thanks I will check this.
think about buffering a cylinder, so you need some memory.
Yes, that is my thinking, to store a whole cylinder in memory and indeed to
record/playback the flux transitions as that is the most general thing to
do.
My last approach to it, was an FPGA which contains the shift register, has
local memory. The supervisor on the side is a stm32f4, which handles the
upload of FPGA, and storing the data on the sd-flash.
Indeed, it is looking like some kind of microcontroller talking to custom
logic is what will be needed. As per another reply a BeagleBone Black might
be a good controller. Not sure on the FPGA front, but Reinhard Heugerger is
using a DE0-Nano. The annoyance is that the BeagleBone uses 3.3V, ST-506 is
5V and the DE0-Nano is 3.3V, so some level conversion somewhere would be
needed.
Just my .0005 cents ;-)
Cheers,