>Maybe someone with a spare drive that could be dismantled and someone
>who could create the specific hardware to write analogically the pack,
>could create a machine for creating alignment packs?! :o)
>
> It was done before with 5 1/4 disk drives... :oD
Hmm, I was under the impression that the alignment packs had everything
hard-coded as to ensure the alignment went okay.
John.
Hi Everyone. I have no idea what these things are called. They show up on
ebay all the time and look like entire 486 machines on a full-length 16-bit
isa card. I'm assuming these are designed to be plugged into a passive back
plane.
I've always wanted to tinker with a computer of this design, but I haven't
had any exposure to them. Is there anything I should look for or avoid
before trying to buy one of these boards? Thanks.
brian
Hi all,
First post here. Long story short, I recently rescued a friend of mine's
Commodore equipment after he'd suffered a fire in his apartment. None of
it caught on fire but some copped a direct hit from a fire hose and was
sitting there for 4 days while I went through the bureaucracy of gaining
access to the place (he's in hospital at the moment but will recover, for
the record).
While this gear isn't particularly uncommon (although the Amiga stuff
might be quite expensive to replace), I'd like to rescue it for him even
if it's just for morale purposes.
Anyway, rusty RF shields have leaked rusty water all over the PCBs and I
really don't know how to deal with it. So far, I've used dry cotton
buds/q-tips to clean off anything visible, but I'd like to know what
people recommend for cleaning the boards properly.
I was thinking isopropyl alcohol - I've previously used it for leaked
caps, but I'm all out right now. Is methylated spirits a bad
substitution?
Speaking of leaked caps, it looks like the water has caused a lot of caps
to leak as well - I've never seen leaking caps in the act, it's always
been dry "after the event" type damage. If there's anything worth noting
about this, that'd be great to know too.
Thanks for any advice!
Cheers,
Dave.
>If the head/voice coil assemblies have been removed you'll have to go
>through the entire alignment procedure which requires a special
>alignment pack. You'll also want to make sure that all of the dreaded
>"DEC foam" has been removed and replaced or you're heads and packs
>won't last long. You'll also want to look at the filters and make
>sure they're in good shape and replace them (if you can find them).
>However, bad filters will also kill the heads and packs.
>
>If the head/voice coil assemblies have been removed how do you know
>that the drives are working?
I noticed that foam almost immediately, I cleaned up the majority but I'll
probably go over the thing with a scraper and the air compressor. I got the
same nasty foam in my SGI Crimson.
Well at the very least the drive powers up with no nasty smells or noises or
the fault lamp and I can get the spindle motor to spin up
>They're one of the standard DEC lamps. I don't recall off the top of
>my head what the equivalent lamp # is but they (or a reasonable
>facsimile) are readily available.
Awesome, that might be a bit better as well.
>For an omnibus PDP-8 you need an RK-8E controller that goes in the
>omnibus chassis. The "hard" part is finding the cable that goes from
>the RK-8E and the drive. For a PDP-11 (unibus) you need an RK-11D
>controller. It is actually a 4 board set in it's own backplane that
>goes in the CPU chassis. There is also an RK-11C for unibus but that
>controller is of the "old style" that has 40 or so flip chips in a
>rack width backplane and is mounted outside of the CPU chassis in a
>rack (requires a separate power supply) that connects to the CPU with
>unibus cables.
Hmm, that might be a bit of a problem as I never see spare flip chips or
anything unless they are on ebay for funky prices.
>If you're not looking for a "blinken" lights machine, you're best bet
>would probably be an 11/34 system. I have several that are "spares"
>but right now I'm swamped and haven't been able to spend any time on
>classic computer stuff.
>
>TTFN - Guy
Well right now I'll go for pretty much anything. I guess a 34 or similar is
a good starter system and on some distant day I'll switch to say an 8/e.
John
Hi guys,
Before I start writing a data decoder of my own (for the disc
analyser), I'd rather like to at least make sure the hardware is
spitting out sane data. Does anyone know of a tool along the lines of
cw2dmk that can accept timing-data input from a file instead of using
(e.g.) a Catweasel?
I was going to do the hardware tests with cw2dmk, but I don't fancy
my chances at figuring out how the ~2500 lines of code fits together,
and how to patch in read-from-file support...
(Apologies if cw2dmk actually /can/ do this; the manpage explains how
to change the output file name, Catweasel port and such, but not how to
make cw2dmk read transition timing data from a file)
Thanks,
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/
Hi at all,
it past much time during i collected all useful info on this my old board
putting all on my website http://elazzerini.interfree.it
<http://elazzerini.interfree.it/>
I hope to can make my board alive soon. A friend given to me all its 32 x
4116 DRAM chips after to have checked all of them.
I buyed on ebay the SWP Double side double density adapter
http://elazzerini.interfree.it/Foto560.jpg and i here to ask: is there
anyone who could indicate where or how to gain the firmware for the bigboard
1 to can make this adapter working or just to gain its 27 original manual?
Thanks for any kind of useful suggestion and please sorry for my not perfect
English.
Enrico Lazzerini - Pisa - Italy
I managed to locate two nicely working RK05J drives (though the voice
coil/head assemblies were removed but I'm trying to get two more from
another guy but damn, those things apparently weigh 80 pounds alone! Think
of the shipping costs! D:) and now I'm really intent on finding either a
PDP-8 or PDP-11 Omnibus system I can run them with. I have been trying my
local Craigslist (as well as others but the listings kept on getting
flagged) but it's a ghost town and I got leads at a place called FreeGeek in
Vancouver but they have never seen a PDP come in through their doors, ever.
I'm running out of places to search and ideas on how to bring my searching
for a PDP to the attention of people who have systems they no longer need or
are willing to part with theirs. I saw alt.sys.pdp8 and alt.sys.pdp11 but
they are both rather empty so I don't know if a yell for help would be heard
there. Any help or offers would be appreciated very much.
Also, most of the bulbs on the front panels of the drives have burnt out.
Are these just regular 12v bulbs? I saw someone replaced the lights in their
drives with LEDs and that would be a bit nicer as LEDs would never have to
be replaced again.
Also, I received only the drives. I saw several flip chips in the thing and
a single empty slot. I'm assuming that the flip chips are the controller and
the empty slot contained a board which gave you a ribbon cable connection to
the omnibus backplane in the PDP or are the chips in the drives "fridge
logic" and I'm missing the controllers?
Thanks.
Hi guys,
I'm just putting the finishing touches on my disc reader hardware. At
this point the disc stepping works (under the control of the FPGA -- you
set the step rate and tell it how many steps to move and in which
direction), and I can access the acquisition RAM on the PC (both read
and write).
So the next step before adding the acquisition module is to make the
thing detect start and stop events. Frankly if you're reading formats
that are index-synchronised (read: IBM PC), then it makes more sense to
read index-to-index than it does to read from $HEAD_POSITION to some
other random place on the disc.
Most folks who have been following this project will know that it has
three ways of starting or stopping an acquisition:
- Index Synchronised. Waits for one or more index pulses.
- MFM Synchronised. Waits for a given MFM sync word to pass under
the head.
- HSTMD. Hard Sector Track Mark Detector. Looks for an index pulse
halfway between two other index pulses, then triggers on the index pulse
after that. For example...
I I I I I I ...
| |
X +--trigger here
(X = the track index mark, + = the trigger point)
Each of these trigger modes can be used in conjunction with a
"delayed capture" mode -- basically, it waits for N events before
triggering. That is to say, you can program it to trigger on index
pulses, with a count of (say) 3, and it'll wait for 3 index pulses
before triggering.
This could be useful for any number of things -- reading
hard-sectored discs, waiting for a few rotations before trying to read
the disc, and probably a few other things I haven't thought of yet.
I'll probably have the HSTMD detector wait for a track-mark, then
count index pulses, which would allow single sectors on hard-sectored
discs to be read with very little effort. This seems more useful to me
than just counting track-marks.
The thing is, I have a limited number of bits available in the
registers (and an equally, if not more limited number of registers). So
what I want to know is... how high does the event counter need to go?
Specifically, how many sectors can you actually get on a
hard-sectored disc? I know 10- and 16-sector discs were (are?)
available, but were any larger sizes (e.g. 20 or 30 sectors) ever made?
Thanks,
--
Phil.
classiccmp at philpem.me.uk
http://www.philpem.me.uk/
Today I became the proud owner of:
- Northstar Horizon w/ 2x 5.25" built-in drives + mucho software
Haven't had a chance to pop the cover and inventory the boards.
- Sony SMC-70 w/ 3 boxes of binders and software
A nice little CP/M system with built-in 3.5" diskette drives
- Morrow 8" external hard drive
This looks to be an MFM interface, or at least it has a 34-pin + 20-pin
header on the rear panel. Anyone familiar with it?
And the strangest one of all:
- OSM "Zeus"
I'm told this was a multi-user business computer from the early 80s, but
the person who gave it to me had no documentation or other information on
it.
Oh, and about 40 boxes of 8" SS/SD NOS diskettes still sealed in plastic
and about 10-20 boxes of 8" SS/SD hard-sectored diskettes, most still
sealed. I'm not sure I really need all the diskettes and may offer them
for the price of shipping - stay tuned.
Also, 4-5 large shelf bins full of 8" application master diskettes and the
entire CPM-UG collection.
This will all take a while to go through.
Steve
--
