My workbench is currently covered with a 9845 is many bits :-). And I am
slowly figuring out just what's inside that darn machine...
Anyway, I believe there was an HP service toolkit for it (based on the
markings on the PSU cover). Does anyone have it?
If so, I have some questions
1) What did said kit contain (other than normal hand tools, which I have
anyway). I am almost sure 2 of the items in the kit were a 'Discharge
Tool' for the power supply and a 'Turn on fixture' to run the machine
without a monitor
2) What does the 'Discharge Tool' consist of? I'll guess it was just a
reisstor connected to a couple of isulated probes, or a plug, or
something. There are some insulated holes on the SPU cover, under them
are bare pads on the PCB connected to the terminals of the mains
smoothing capes. The instructions are to insert the tool into 2 of the
holes, then into the other pair, then to check the voltage between the
holes you put the tool in (basically, check the caps are discharged)
before removing the PSU. From the size of those capacitors (1800uF, 200V,
small coke-can size), I would agree!
3) More importantly, what does the 'Turn On Fixture' consist of? Again
I'll make a gues. It's a little PCB that goes into one of the edge
connectors in the monitor pillars. But which connector, and what's on the
PCB? Does it just short a couple of pins together to complete some kind
of interlock circuit, does it contain load resistors, or worse, does it
contain ICs?
HAs aonone else been foolish enough to dismantle the printhead? Suffice
it to say it consists of a normal PCB that connects to the printer cable,
a seramic substrate containing the (thermal) printhead heater elements, 7
seramic hybrid circuits that contain the driver cirucits, and something
like 35 of those metal-rings-round-elastomer connectors (like those
between an HP41 logic board and keyboard) to link everything up...
-tony
>From: "Tom Jennings" <tomj(a)wps.com>
>
>On Mon, 13 Dec 2004, Carlos Murillo wrote:
>
>> > It isn't much good for home use. In fact, lamps don't
>> > do as well on DC as AC because of the electrical effects
>> > of the wire evaporating ( not sure which end goes first ).
>>
>> Ah, the "Edison Effect".
>
>I'd heard of the effect, but not for a long time, and probably paid little
>attention to it :-)
>
>So, how pronounced is this DC-filament effect? If I collect
>dead lightbulbs from my cars, should I see filaments with gaps
>burned towards the ground end more often than not?
>
>(Tapered filaments would fix this.)
>
>
Hi
I would think the effect is smaller today since we don't
still use high vacuum bulbs. Most have a partial atmosphere
of an inert gas. The Edison effect is the same as used
in vacuum tubes. You still might see a slight bias towards
one or the other end.
You have to realize that work hardening and fracturing
of the filament in an auto is a large factor in shortening
the life of these lamps.
Dwight
CNN has a magazine style show called NEXT@CNN that has a gaming theme
this week. Included is, of course, a discussion of vintage gaming and
what the kids today think of the old stuff.
It's funny to see the old Atari X-Wing run side-by-side with the modern
version.
About 20 minutes into the show is a "bump" for the 30th anniversary of
the Altair computer featuring a machine from my collection including a
shot from this year's VCF!
Erik Klein
www.vintage-computer.comwww.vintage-computer.com/vcforum
The Vintage Computer Forum
Makes perfect sense :)
A novice was trying to fix a broken Lisp machine by turning the power
off and on. Knight, seeing what the student was doing spoke sternly:
"You can not fix a machine by just power-cycling it with no
understanding of what is going wrong." Knight turned the machine off
and on. The machine worked.
the only sound physical reason for fractions is cooking... the general populace is so technically illiterate that is really doesn't make a difference whether things are in fractions or decimal. They really don't have a clue anyway. When was the last time you heard any clerk actually count change out or someone realize that 1/4 cup is 1/2 of a 1/2 cup...
The people that like decimal systems don't understand fractions and the fractional people don't know what to do with a decimal point.
As for eight fingers, I like my thumbs...
-----Original Message-----
From: "Dwight K. Elvey" <dwight.elvey(a)amd.com>
Sent: Dec 13, 2004 3:12 PM
To: cctalk(a)classiccmp.org
Subject: Re: electro-Physics: 17.3409 volts
>From: "Paul Koning" <pkoning(a)equallogic.com>
---snip---
>
>Some of this discussion reminds me of the "arguments" why the metric
>system is inferior to the US system of measures.
Contrary to what Tom Jennings states in a later post, there
are sound physical reasons for using fractional systems
when dealing with the physical world.
anyone have the DOS version of Empire, Nethack (an older version that
does not need dpmi),
I had a DOS version of tetris too (using regular characters in 40 char
mode) so I am looking
for that too.
Any websites that provide old DOS programs for download?
Thanks!
All this talk about getting older drives to work on newer hardware got me
thinking about a totally different track on how to get this done (not to
mention the previous subject was referencing a 5 foot, 3 inch floppy
drive... ;-) )
There are VAXen that have SCSI bridgeboards to control 3.5" 1.44Meg floppy
drives via the SCSI bus - how "controllable" are those, WRT different
drives, data rates & low level programmability? I have one, but other than
"it gives my VAX a floppy drive" I know very little about them.
(I know I'd been thinking of getting another one so I could use 1.44Meg
drives on a CoCo system under OS-9 equipped with a SCSI board... but have
yet to get around to it.)
Also, would those bridgeboards support 2 drives?
Just an "out of box" thought...
Roger "Merch" Merchberger
--
Roger "Merch" Merchberger | A new truth in advertising slogan
sysadmin, Iceberg Computers | for MicroSoft: "We're not the oxy...
zmerch(a)30below.com | ...in oxymoron!"
They also made SCSI ZIPs - used on Macs and SGIs, etc. The parallel models
used a proprietary SCSI over parallel protocol, at least on the early ones, and
were slower than snails. I've never popped one open to see if it is possible
to revert to SCSI, though (probably not). I think I heard that later models
used an encapsulated IDE protocol. I'm not sure if it is still the case, but I
think some of the old (2.2.x) Linux kernels had some documentation about the
protocol.
It could be possible to hack together a similar interface for floppies,
though (encapsulate over parallel port)
the one floppy deal is not really a bios issue, it is a hardware issue. As long as there are two drive select lines coming from the hardware, then the mb can supprt two drives even if there is not bios support. My ASUS P4 mb only supports one drive and I suspect that there is only one drive select. Bios code is meant to support the hardware that is present. At least that is the way is has been for 23 years...
-----Original Message-----
From: Robert Feldman <r_a_feldman(a)hotmail.com>
Sent: Dec 12, 2004 11:13 PM
To: cctalk(a)classiccmp.org
Subject: Re: 5-1/4' drive on modern PC
I've been wading through a lot of digests, catching up with the list, so
this post is a bit late in the thread.
One thing to watch out with on recent PC's is that the BIOS might not
support more than one floppy drive. I found that out on a SOYO motherboard I
got last year. The BIOS can handle 360KB and 1.2 MB 5 1/4" drives, as well
as 3.5" drives, but you can have only one drive attached at a time.
Bob
If you can read the disks, this might be of interest
http://home.iae.nl/users/pb0aia/cm/8-525.html
- cabling to use a 5.25" HD (1.2MB) drive in place of an 8"
and
http://nemesis.lonestar.org/computers/tandy/hardware/model16_6000/floppyfix…
ml
hints specific to the TRS80
Found it on the web and have it in the pile of projects to try out on my Z-80
when I get around to it. although I don't know how much longer 5.25 HD
diskettes will be easy to get-
Scott Quinn
P.S. I'm new to Classic Computing, so don't take my word for it-please double
check before risking your machine
