two unrelated questions:
first : where can I find software/support for my NeXT computer on the
web...... searching the web for quite a while has not produced any good
sites.....
Also, I'm looking for an old but WORKING Microvax or VAXStation on which to
run (read : play with) VMS -- anyone have any good ideas on where to look -
i've been watching ebay but most systems that come up for auction look like
"fixer upers" or are expensive. I just need the basics.......
thanx
mark
-------
ICQ 40439199
http://www2.msstate.edu/~mja2
From: "Richard Erlacher" <edick(a)idcomm.com>
> Assuming you've used a real wire, it certainly will keep the two points
> at the same potential.
I love to see an idealist. Is your wire carrying zero current, or is
it a superconductor?
------------------------------------------------------------------------
Steven M. Schweda (+1) 612-785-2000 ext. 16 (voice)
Provis Corporation (+1) 612-785-2100 (facsimile)
5251 Program Avenue #100 sms(a)provis.com (e-mail)
Mounds View, MN 55112-4975 sms(a)antinode.org (e-mail 2)
well . . . back when dinosaurs roamed the earth, and IMSAI was a major
computer maker, the 25.2VCT was about as common as its companion, the 6.3V
filament heater (starting to sound familiar?) and there were a few supplies
which got away with that. If you filtered well and used only one diode at a
time, you still had enough headroom to allow for 2.2 forward volts in the
regulator.
I've got switchers in the basement which have adjustable voltages for three
(5-10Vdc, +/-12-18Vdc). The previous statement that switchers like a
constant load is quite correct, though and what is meant there is that the
switchers don't like capacitive loading, nor do they like loads which are
intermittently on.
S-100 boxes sometimes housed floppy and hard drives, though, and if it was
only the 5-1/4" types, and floppies only, the +12 saw its worst nightmare.
It saw nearly fully on, vs nearly fully off, since one floppy took more +12
than all the RS232 ports.
I don't know where they're going to end up, but I believe that the power
supply thing will have toox have quite a bit more attention than it's gotten
so far.
My advice to anyone wishing to sell hardware in the quantities they're
likely to sell, would be to build a kit, no assembled units, find a catalog
standard switcher to sell them, and use the fact that it's all just spare
parts to bypass the FCC reg's. Sell the box top, sell the box bottom, the
front, the rear, but no fully assembled boxes. Sell the front panel as a
replacement part, too. That way there's no enclosure to require approval.
What's more, it will make the phone support burden lighter.
If they want a fully assembled and tested unit, tell them to buy a PC.
Dick
-----Original Message-----
From: Allison J Parent <allisonp(a)world.std.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Tuesday, August 17, 1999 8:00 PM
Subject: Re: imsai 2
><Anyway, why does it have to be one transformer? Why not a 12-0-12 for the
><16V lines and a 6V one for the 8V line (those should produce DC voltages
><within the range of any normal S100 board regulator). Such transformers
><are trivial to obtain.
>
>Then you'd end up with the piece of crap altair supply...
>
><There is a myth doing the rounds that PSUs -- even simple linear PSUs --
><are impossible to design. No idea where it came from...
>
>Because any error means all your silicon is junk. Also if you make a
>small error the core you using could get quite hot. Or maybe the ripple
>from switching exceeds the reasonable level by say a volt or two. Then
>there are the high current ground loops that cause instability at
>something approaching max load or minimum load. The worst is when you
>forget the chopper side has 300V on it, S*!^^ d@**. The number of
>errors that can be made are far higher. Then again having designed a
>few, once you've done it you learn... mostly everything they taught you
>was far from enough. that and fixing all those that were really not so
>well designed.
>
>Allison
>
Flame me if you want... But it seemed significant enough to mention.
Should be interesting to see where this one goes price wise. Minimum bid
is $5,000US.
-jim
---
jimw(a)computergarage.org
The Computer Garage - http://www.computergarage.org
Computer Garage Fax - (503) 646-0174
>>> Coming soon to www.computergarage.org - the CBBS/NW on-line archives
>>> Coming to VCF III (2-3 October 1999) - CBBS/NW live!
At 10:31 AM 7/21/99 -0400, you wrote:
>> The TRS-80 Model 100 had a much more useable 40x8 character display. The
>> Model 100 also had a built-in editor, address book, schedule, and
>
>The real question is who made it for tandy and what other name did it sell
>as?
It was available as:
NEC PC-8201 *
NEC PC-8201A *
Olivetti M10 *
Kyocera KC-85 *
Tandy M100 *
Tandy M102 *
and later, upgraded as:
NEC PC-8300
Tandy M200 *
The NEC PC-8201 was the Japanese version of the 8201A. Followups that were
*not* related include:
NEC PC-8401A *
Olivetti M15 *
Tandy M600 *
I'm not sure about the NEC PC-8500 though.
* Examples I have -- I'm looking for an 8300 and would like a non-modified
m102.
--------------------------------------------------------------------- O-
Uncle Roger "There is pleasure pure in being mad
roger(a)sinasohn.com that none but madmen know."
Roger Louis Sinasohn & Associates
San Francisco, California http://www.sinasohn.com/
At 05:49 AM 7/21/99 -0400, you wrote:
>While the Epson HX-20 can lay claim to being the first laptop, it had some
Epson HX-20 was the first laptop-sized computer. Toshiba claims they
coined (and trademarked) the term "laptop", beginning with their T-1100.
I'm going to have to chase down that Byte reference; I seem to remember
"lap-computer". The m100, being a fair bit more usable and available,
became a hit with journalists, and got quite a bit more fame.
>Now, does anyone know which the first notebook was? Was it the Grid
>Compass, or the DG/One? Or something else I've never heard of?
GRiD Compass, in Fall '82, followed by the Sharp PC-5000 and the Gavilan
(both in '83; I'm still trying to find out which came first.)
--------------------------------------------------------------------- O-
Uncle Roger "There is pleasure pure in being mad
roger(a)sinasohn.com that none but madmen know."
Roger Louis Sinasohn & Associates
San Francisco, California http://www.sinasohn.com/
>>> Tony Duell <ard(a)p850ug1.demon.co.uk> 08/17 6:01 PM >>>
>
> Upon the date 05:01 PM 8/17/99 -0700, Wayne Smith said something like:
> >What's the best way to replace a broken belt in a DC300 tape cartridge? Is
> >there a source for new belts?
>
> Not likely unless there was a real unusual need and someone already
> supplies them. Normally, the mfr (3M, Dysan, or whoever else made them)
> figures the user will typically throw out a defective cart and use a new
> one. Hence, the assumption there's likely no aftermarket supplier,
> especially now since DC300's have been out of popularity for several years.
In my experience, spares for tape cartridges are impossible to obtain,
other than by dismantling a new cartridge. This is worth doing if you
have a defective catridge with some important data on it.
> Best way to deal with this is to find an unusable tape with a good belt and
> very carefully remove it and very carefully replace it on your defective
> one. Probably should find one of the same manufacturer just to be safe.
> It's stretched rather taught and will be a real circus to replace. Got
> three or four arms hanging off you? :) Tony, have any thoughts on this?
Argh! (that's me remembering what happens when you try to do this).
The belt runs from the 'drive puck' (the roller that's driven by the
capstan in the drive), between the 2 tape spools (it rubs on the outer
layer of tape on both spools, thus maintaining the tape tension, and
causing the tape to move at constant speed), and then round one or two
idlers. The better cartridges have a fixed idler (on a post fixed to the
baseplate) in the bottom corners. Some lesser cartridges have a
'floating' idler between the 2 spools at the bottom. That sort is a right
pain to rebuild, and some of them were glued together (particularly on
the smaller tapes), and these will drive you mad!
OK, assuming 2 fixed idlers and screwed-together housing. It's best if
you have 2 new tapes - one to take to bits for spares, the other to show
you where all the bits go.
Start by undoing the screws on the bottom of the cartridge, and pull off
the cover. Remove the door and its spring. Take off the empty-ish spool
(unwind the few turns of tape if necessary), the idlers, drive puck and
belt. Take off the full spool, making sure you don't spill tape
everywhere.
Clean up the rollers and housing.
Now to reassemble. Put the full spool on the 'supply' side. Put the drive
puck, idlers and belt in position. The belt will be fairly taught even
now, and should stay in place
Drop the empty spool over the other spindle. It won't drop down as the
belt gets in the way. Using a cocktail stick/plastic spike/etc, hook the
belt round the spool.
Evertything will fly off (:-(). Try again, and after about 5 goes you'll
get it in place.
Run the tape round the guides and put the end in the gap between the belt
and the empty spool. Hold everything in place and carefully turn the
drive puck. Keep on guiding the tape until 2 or 3 turns are wound on.
Counter-rotate the 2 spools to tension the tape. You will have to force
them against the friction of the belt.
Refit the door and spring. Often you can fit the spring into a hole on
the bottom of the door, tension it, and hook the end into a slot on the
door. Then drop the assembly onto its post, and finally release the spring.
Put the cover one, and fit the screws.
Wind on the tape a few more turns, and try it in the drive. Start by
'retensioning' the tape.
-tony
>>>Thanks for that great description, Tony. I don't know whether you've inspired or depressed me. ;-)
Wayne
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<Well . . . freight cost alone might be justification for using switchers.
<Nevertheless, I don't see a use for the regulated supplies in connection
<with a bus which by definition uses on-board regulation. If the supply
<actually provides the specified voltages, that's a different situation. Th
<typical S-100 box, IIRC, used lots of amperes, even for just one memory
The average S100 crate was +8 20A minimum and many were 25-30A on that bus
never minding +12 at some 6A and -12 at same. The boards DO heat a bit
and fans were typically 110V 100-140CFM models!
Allison
<What puzzles me is why the IMSAI folks decided to use a switching power
<supply when the box and everything else already supported the needs of the
<S-100 with the previously available and now quite inexpensive unregulated
<supplies of yesteryear. One of the main benefits of the S-100 was that it
It would hae to be regulates at Vreg(oncard)+3V to work. or every cards
would ahve to have the regulators ripped off. Add to that +5V bus sag
>from end to end... not a good thing. This is why most every other "decent"
bus (STD, Multibus, Eurocard, Qbus, unibus...) were either physically short
or used multiple supplies powering short segments.
On a more serious vein, cost, availability and oh UL/CSA/TUV/<your favorite
safety/electrical/communications standards agency here>.
I should look at this hack to see how much damage there is... likely the
idiots have a PC inside wiggling the lights and thats all.
Allison
