3 Nov
2013
3 Nov
'13
3:37 p.m.
-----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-
bounces at classiccmp.org] On Behalf Of David Gesswein
Sent: 03 November 2013 17:45
To: cctech at classiccmp.org
Subject: Re: Looking for a MicroController Recommedation
On Sat, Nov 02, 2013 at 05:25:05PM -0000, Robert Jarratt wrote:
and
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.
I was playing in the same area. I am using the beaglebone.
http://beagleboard.org/Products/BeagleBone+Black/
The PRU have a 200 MHz clock so you can measure the edge to 5 ns though
you can't respond to the next edge for a while depending on how many
instructions. I have the PRU writing the transition times to main memory the ARM doing the decoding. I was planning to make it
a drive emulator
after
getting reading working well.
I made by own cape to convert signals to proper level and drive. 4 chips
wirewrapped.
I have it reading MFM disks. One disk I had around I get about twice as
many
sectors with CRC errors as the labels says. The other
disk has a lot of
errors.
The rest of the disks don't go ready. Next was to
hook them up to the
proper
controller and see if the errors are real or my MFM
decoder needs more
work.
Its been stalled for a little while since some DECtapes and LINCtapes came
by
to be read before forwarding them on. I modified my
cape to talk to my
TU56 (using the G888's in the drive) to read/write DECtapes & LINCtapes.
That now is working pretty well and the tapes are read so I may have some
time for this again.
I can put my stuff online if you think you wish to use the beaglebone. It
really
needs some more time to clean it up.
Hello David,
I am going to do a little bit more research, but this looks like a promising
avenue. If I do go down this route I may take you up on your offer to take
the stuff you have done so far, if that is OK.
Regards
Rob