I've just had one of the disk drives in my TRS-80 Model III start to go
south on me, and before I crack the case and get down to serious diagnostic
work, I thought I'd check with the list to see if the symptoms ring a bell
with anybody.
I believe that the drive in question is a stock factory install; it's the
secondary drive in a fairly low serial-numbered Model III (in the 50,000s).
The first sign of trouble was that the drive began returning spurious "Disk
is Write-Protected" errors, which would go away upon reinserting the disk.
Now it's begun episodes of returning TRS-DOS Error 08 ("Drive Not Ready")
messages for all operations. The activity light functions normally, and the
drive hasn't made any alarming sounds. It does not spin up the disk when
it's in this state. After a while, it'll begin working again on its own.
I realize there are any number of replacement drive solutions out there, but
this is a system where I'd really like to keep the original equipment up and
running until it just can't be patched together any longer. (I can't really
explain why I'm so fond of this thing; I just am.)
Thanks in advance for any suggestions, or just things to look at first.
I've got a scope and logic analyzer I can use for diagnostics, but my
knowledge of disk systems beyond the tracks-and-sectors level is marginal.
--- JP Hindin <jplist2007 at kiwigeek.com> wrote:
> What on Earth is this?
>
> 110206772756
>
> I'm guessing its OT because of the SMD devices in
> the centre ring, but it
> is weird enough I'm willing to risk Jay's wrath to
> find out what it is.
It looks a lot like the readout electronics that might go on the
end of a high energy physics cylindrical wire chamber. Go
to google images and look for "wire chamber".
For even more science-fictiony particle physics detectors,
google for "Gammasphere". I understand it made an appearance
in the Hulk movie!
Tim.
>From the BOFH column in The Register (http://www.theregister.co.uk/2007/12/21/bofh_trivia_quiz_200712/):
Are you an old bastard?
7. >Clunka Clunka Clunka< is the sound you would most associate with:
A. The clothes dryer
B. A washing machine with an imbalanced load
C. A flat tyre on your car
D. A tape safe door shutting repeatedly on an annoying user's foot
E. An imbalanced DEC RM05 Disk assembly moving around the computer room by itself during a head crash
> From: Brent Hilpert <hilpert at cs.ubc.ca>
> Subject: Re: The 2N2/256-BSCP [was: Homebrew Drum Computer]
>
> Another approach to discrete flip-flops can be seen at:
>
> http://www.cs.ubc.ca/~hilpert/eec/misc/CasioAL1000Tech/electronics.html
>
> The stacking of multiple inputs into the basic FF structure was another
> technique from the discrete days. Helps reduce the amount of gating (and
> hence
> transistors) required, for instance when making a parallel loaded shift
> register or counter, although they were lots of other novel uses. (Some
> aspects of logic design were narrowed with the introduction of ICs for the
> sake
> of standardizing on elements that would fit in packages with limited
> connections.)
>
Very similar to an East German calculator that I am partway through reverse
engineering, a Soemtron 220.
www.soemtron.org/downloads/board10.pdfhttp://www.cs.ubc.ca/~hilpert/eec/misc/CasioAL1000Tech/electronics.html
Looks like thees pages might help in that task thanks for the link
Mike.
> From: dkelvey at hotmail.com
> To: cctalk at classiccmp.org
> Date: Fri, 21 Dec 2007 08:21:53 -0800
> Subject: RE: The 2N2/256-BSCP [was: Homebrew Drum Computer]
>
>
>
>
>
>> From: mcguire at neurotica.com
>> Date: Fri, 21 Dec 2007 08:52:06 -0500
>> To: cctech at classiccmp.org
>> CC:
>> Subject: Re: The 2N2/256-BSCP [was: Homebrew Drum Computer]
>>
>> On Dec 21, 2007, at 2:07 AM, dwight elvey wrote:
>>> As a cheaper alternative to a tunnel diode, do a search for
>>> a Lambda Diode. I used one of these circuits once to make an
>>> oscillator that ran at over 100MHz.
>>
>> Oh my, there IS an almost-equivalent-to-a-tunnel-diode circuit!
>> That looks really, really neat...I will have to play with that!
>>
>
>
> Hi
> To better approximate a tunnel diode, you'd have
> to put a resistor in parallel. I don't recommend doing
> this as it only degrades the negative resistance.
> Still, if one was to use a pair of these for a flop, it
> might be more stable since at the higher voltages,
> unlike a real TD, it completely shuts off. Without the
> shunt resistors to bypass some current the circuit
> might oscillate.
> Dwight
>
Hi
Another negative resistance device is the DIAC. These are
really cheap but these are knee type curves instead of
S type, like the TD and Lambda.
One would have to rearrange these in a parallel configuration
for a latch or flop, similar to the neon circuits.
The TD has the advantage that the stable state is lower
current, not higher current.
The disadvantage is that that tends to increate the impedance
of the storage net making it less stable and more susceptible
to noise. That is why I recommend the shunt resistor to
decrease the impedance.
Dwight
_________________________________________________________________
Share life as it happens with the new Windows Live.
http://www.windowslive.com/share.html?ocid=TXT_TAGHM_Wave2_sharelife_122007
DUT (Device Under Test) board
for an automatic board tester.
The pins around the edge are called pogo pins
and mate with the base of the tester.
You see these a lot on eBay, sellers never have a
clue what they are.
Repost since the mail server doesn't seem to like to work outside of
business hours
I've been looking at the garage, and here's a list (for those who are
waiting (you know who you are), I have the SIMMS and the Xyplex ready
to go, the post office is a bit of a nightmare now though).
(1) the definitely on-topic stuff
Sun-3 and Sun-4 VME stuff. (note-Pat gets first call, since he's
sending me some E3k stuff)
4x 501-1333 32M Sun 4/400 (/470, /490) ECC RAM (128MB total)
3x 501-1102 8MB Sun-3/200 ECC RAM (also works on 4/260 & 4/280 per FEH)
501-1167 Sun-2 SCSI and 9U->6U adaptor (external DD-50 conn.)
501-1276 FDDI adaptor
501-1539 IPI-2 adaptor
501-1206 Sun 3200 CPU, no PROM onboard.
501-1316 Sun 4300 CPU for parts
501-1203 Asynch serial multiplexor
Sun 50-pin drive lunchbox.
Assorted stuff (well, the Xylogics can go in a Sun)
Xylogics 450 Multibus SMD controller, with or without a Sun VTM adaptor.
DIGITAL Alpha Multia VX42 (233MHz, cache) with new battery.
SGI IRIS Indigo Express (GR2 XS/XS-24/XZ/Elan) boards:
ZB4 Z-Buffer
3x VM2 bitplanes
Personal IRIS PSU and TFLU skins (no cracks, door in place)
Xyplex Maxserver 4000-series terminal server, telco style outputs,
fully populated.
still many 4MB 30-pin (9-bit) parity SIMMS (80nS) (free)
one Sun USIIi 333MHz/2MB Ecache module (U5/U10)
Apple M0130 400K Macintosh floppy
DD-50 interface drive box w/ PSU.
The "pushing it" section:
Unholtz-Dickie OSC-1S sweep sine generator
Graphtec WR3200 thermal arraycorder (8-channel chart recorder)
HP 3746A selective level measuring set
HP 5061A Cesium beam frequency standard (CS beam likely needs work)
HP scope frame that I've not tested yet - no plugins, email if
interested as I'll test it later.
Part of a satellite tracking system. Figure no interest, but I should
ask before scrapping. Scientific Atlanta. On a more practical note,
these have 3U rack cabinets, aluminum, pretty nice. Not set up for
computer stuff specifically, but hackable.
Renton, WA. If anyone wants to trade, I'm looking for a decent
soldering setup, PROM/PLD programmer (need not be fancy), interesting
computer stuff (perhaps some SGI Origin 200 dual processor modules,
largish 72-pin parity SIMMS, even very off-topic but a couple of years
old stuff that could run W*****s (but won't). Don't think any of this
runs up anywhere near the value of a smallish PDP-11 or HP 2100, but
figured I'd put it out as a pipe dream), or other electronic/computer
stuff. Cash always accepted, too.
Otherwise make offer, some I might just give away.
---------- Forwarded Message ----------
Does anyone have a source for the keyboard for this PC? This keyboard connects to an eight pin mini-DIN socket.
Also if anyone has pin-out information for this keyboard or this PC's monitor outputs, (B/W-5 pin DIN connector, analog RGB-DB15 connector, or digital RGB), it would be greatly appreciated.
I am also looking for pin out information for my Zenith ZVM-131 monitor purchased new in 1985 but did not have a manual with it when we received it.
Regards,
Brett
_____________________________________________________________
Need cash? Click here for low rate home equity options.
http://thirdpartyoffers.mybluelight.com/TGL2321/fc/Ioyw6i50uhFS2ETSxvvPdN8f…
Tall Corporate cab, plus five (all bad hda) RA81 drives. The corporate cab
includes an 861A power supply. This 861 has a power cable half the size of
my arm coming out of it.
The cab was sold with four RA81's in it, so it has all the correct DEC rack
hardware & cable management pieces for all the SDI cables (several of the
bolt on SDI in/out modules), the power sequencing connectors for in/out of
the rack at the bottom, etc. It also has a metric buttload of SDI cables and
power sequencing cables. All headed for the skip unless someone is willing
to pay shipping for any of it. It will be gone within 24 hours.
I don't want to ship dead drives or anything, but I'm willing to unbolt any
small rackmount hardware or brackets people may want.
Jay
On Thu Dec 20, 2007 at 17:01 Dave McGuire wrote:
> > Well, if you put no limit on the number of diodes (just 3 terminal
> > devices), you can go a heckuva long way using tunnel diodes or even
> > diacs.
>
> I'd love to find a huge stash of a few thousand new-old-stock
> tunnel
> diodes. :-(
>
> -Dave
Me, too! I've never seen tunnel diodes going for less than $50 each,
so if I had a few thousand I'd sell most of 'em for $40 : )
-Bobby
