----- Original Message -----
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
To: <cctalk at classiccmp.org>
Sent: Saturday, September 07, 2013 7:20 PM
Subject: Re: Soft Sectoring a RK05
A few monthes ago there was a discussion about modifieng 12 secor packs
make them 16.
very handy but not something I have the equiopment to to, however I have
been experimenting with softsectoring an RK05 and tonight got a
16 sectore format of a 12 sector pack.
How 'repeatable is it? If you format a pack as 16 sectors, remove it,
wait a bit, put it back in, does it all work? I assume so, but it can't
hurt to check.
I dont know yet, so far al lI have done is half a dosen formats on one pack,
all ok, yes read only check would give a better take , i will look at the
format program, should be able to startit at the read check so missing out
the format part, or I may just rty and do a os8 restore image and see how
Im pulling out the raw secotor/index pulse train
from the M7700, feeding
this into a PIC18F8720 and using this to synthesize a 16 sector train
is fed back into the M7700, ok it does mean I have to modify the M7700
its only 1 cut track and 2 wires out, also its not at all peroid correct
I really do prefer to keep my clasiscs using technology that could have
been around at the time (actually, one reason I use classic computers in
the first place is that I find the hardware a lot easier to understnad
than the modern stuff, but anyway).
In general I agree and find fault finding and repairing ( and having to)
down to basicly gate level gives me graet deal of stisfaction and to be
honest is probably what " drives me", if it all worked all the time then it
dowdent be half as interesting.and as you say this technology can still be
repaired , later is much harder. This exercise has meant that I have had to
delve into othe inner working of the RK05 drive so Iv leant a lot , this
drive worked when I got it so iv not needed to look at it in detail before,
the RK8E on the otther hand needed lots of work, this board set is a bit of
a nightmare, at laest 2 versions and lots of engineering change patches, in
fact I ended up changing the design a bit and adding an extra latch to get
rid of a timing problem that was givving the CA register an extra incument
I am just wondering how impossible it
would be to implement much the smae solution with
simple logic ICs.
This will be the next version, TTL only
sorry Tony ) but if it means I can have more
than the 1 usable 16
pack I have right now then im a happy bunny.
My more immeidate problem (for suitable values of immediate, it's not
going to get worked on in the nxt few months) is to come up with a
working HP 25 sector drive.
I do have an HP7900, which is the right drive for what I want to do, but
it is not in good shape, and the heads may well not fly. If I can get
that drive to work, the problem then becomes making a 24 sector pack,
soemthign which is easier than making a 16 sector one (it is just a
matter of cutting an extra notch between each pair of existing notches
(well, ignore the index one).
If the HP drive is not repairable, then I have to come up with some
alternative. IIRC HP drives spin faster than DEC ones (and hav a higher
data rate as a result), so using an RK05 is not going to be totally
Well shall see...
Thats going to be interesting , and lots of fun..
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Version: 2012.0.2242 / Virus Database: 3222/6145 - Release Date: 09/07/13