The only problem I have with my rather conventional equipment in terms
of RFI is when my monitor changes modes, and I am using an AM
receiver right next to it. The sound flickers a bit. I would think
that the home computers and games systems like C64, PCjr, etc.
couldn't put out too much RFI, since they used TVs for monitors...
>
>Maybe that's why the 5150 is more desirable :-). After all, you can
>always fix those given the techref - no custom chips, full schematics,
>etc. No problem...
>
>> Now to add something new to the list... What are the best/worst for
RFI?
>
>Well, my old Tandy model 1 radiates a bit.
>
>I would think some of the old DEC backplanes with no metal screening at
>all (like the RK11-C and DX11, and even machines in the BA11-F, like
the
>PDP11/45) would not be trivial to get through EMC tests. I've never had
>problems running any of my machines with normal broadcast radio/TV in
>adjacent rooms, so it's not a big problem in that sense, but it may be
a
>pain for amateur/SWL work.
>
>Worst problem I know is that the harmonics of both the TV line scan and
>the VGA line scan are close enough to our standard time service (Rugby
>MSF on 60kHz) to totally swamp the RF stage of any such receiver. I
>generally have to put the aerial/RF stage in another room at least.
>
>-tony
>
>
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>I used to collect coins when I was a kid, and the Blue Book (wholesale
>values) and Red Book (retail values) were my bibles. Coins had a pretty
>good grading system, and you could find fairly reliable production data.
>I don't know of anybody that has tried to do anything close to this for
>computers.
I have "A Collector's Guide to Personal Computers and Pocket Calculators"
by Dr. Thomas F. Haddock that attempts to price old computers. They
don't do a very good job, though. According to the book, an Apple IIc is
worth $200 - $400 and a Lisa 1 is worth $50 - $150. To be fair, though,
the book is from 1993. Anybody know of anything more recent?
Tom Owad
In a message dated 98-05-15 21:07:04 EDT, you write:
<< > Now to add something new to the list... What are the best/worst for RFI?
>>
I had an apple ][+ which caused major tv interference. my particular apple
had a revision 6 motherboard i believe. later models had a different board and
had some metal shielding on the inside. earlier models had no provisions for
it.
david
Noone really cares about used-up silicon. My uncle works at a major
company that builds semiconductor factories (A meta-semiconductor
factory?), the name of whic escapes me. It is the major one, though.
Anyway, he has an bad wafer, of Pentium chips.
By the way, is it theoretically possible to make an IC with only
a prototype IC and an arbitrary amount of machinery?
>>into it within the first 5 or so hits.
>
>Yes, there's an image of the 4004 die on Coulson's site. But if
>collecting classic computers was only about finding GIFs on the
>web, we'd all have pretty big collections, wouldn't we? :-)
>
>Sad to say, but I'd like to get two 4004s - one to smash, one to
>keep as-is. I get the impression they're considerably less rare
>than many of the computers we collect, having been used in more
>popular computerized devices.
>
>For that matter, I'd like to get more rejected silicon dies.
>I have one three-inch wafer containing an HP CPU from the early
>80s, and I lusted at the eight-inch wafers I saw at a friend's
>office. Anyone know anyone at a foundry? Or do they religiously
>recycle the silicon after it's been contaminated with circuitry?
>
>- John
>Jefferson Computer Museum <http://www.threedee.com/jcm>
>
>
>
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In a message dated 98-05-13 10:41:03 EDT, you write:
<< Actually, David Greelish (of "historically brewed" and the "classic
computing society") is attempting just such an online price guide. His
efforts so far can be seen on:
http://members.aol.com/mtpro/ >>
what a joke! i just webbed there not long ago and checked his price guide. an
H89 for $400? wow, i got mine for free! a pcjr for $50? i cant even give one
away! a trs80 model 1 for $200? yea, right! from his "prices" i could sell
part of my collection for over $1500. the list is quite sparse though. what
about my osi or my portable pc or mac512k with a hyperdrive or my tandy 102 or
atari portfolio? i seldom take seriously anyone who attempts to put market
prices on old computers. for some light reading and humour goto the above url
and check for yourself.
david
<> NS* were setup with 16-62k of ram. There were three common OSs run on
<> them NS*dos(nothing like PC dos), CP/M-80, there was also UCSD pascal
<> P-system. I believe NS*dos reached at least V5.4. They didn't not use
<> a monitor or keyboard as a terminal was commonly used.
<
<While agreeing 100% with what you say, is there any reason why you
<couldn't put one of the many S100 video boards into an NS* and plug a
<monitor into that You'd probably still need a terminal for text I/O, but
<I can't see why you can't have a separate graphics display as well.
Typical NS* was set up that way. That was not to say they were configured
with an assortment of third party cards. Mine never had a NS* ram card
>from 1978 on, already had Seals and PT 8kx8 on hand. Also used a PT
VDM-1 until I got an H19 a few weeks later. No doubt over time most any
combination of cards made it in to a NS* crate. It was a good crate for
upgrading and mods.
Allison
Anyone interested in a Head Start Explorer? (Laptop -- sorta -- XT w/HDD,
needs CGA monitor).
- HDD OK, has a virus
- Broken backsoace key, some others feel funny (stuck)
- Broken on/off switch, needs to be pushed in with pen
manney(a)lrbcg.com
"Un sot trouve toujours un plus sot qui l'admire."
Hi, all!
I'm kinda novice around here... So can't get at once if the topic will be
interesting to you chaps.
In my school days I used to work with programmable calculators (Soviet ones
- .ua was part of SU that days). So if smb finds the topic interesting I can
try to recollect all I know about 'em and post right to the group. And I can
assume they could be called classic 'cause the last model of this
"Elektronika MK" series was issued ~11 years ago.
So, if find it worth typing please mail me to andy(a)topaz.kiev.ua
-andy
As a teen, I remember scavenging 7400-ish chips and whacking
them along the edge to split the ceramic to expose the silicon die,
then examining them under a microscope. With that experience in
mind, I've saved a number of chips from junked equipment over the years.
Has anyone else out there assembled a microscopic chip collection?
I've thought about removing the dies from the chips (hmm, might
be tough because they're so fragile) and mounting them on slides.
Sam's message about the 4004 made me think about this. Coulson
suggested a good way to get a 4004 would be to find one in an old
cash register. I checked the net for sites for cash register
repair companies, and sent a few e-mails, but none had spare 4004s.
It would be fun and almost educational to outsiders to have a
series of slides showing the evolution of the common Intel chipset,
or memory chips.
- John
Jefferson Computer Museum <http://www.threedee.com/jcm>
I remember smashing chips. Was pretty difficult, actually. I tortured
memory chips. I think this might be a good idea. I can imagine a
fairly large market for this, if you're into that sort of thing.
THe only problem is: how many 4004s are left, not counting the ones
on Voyager? How many were made?
>them along the edge to split the ceramic to expose the silicon die,
>then examining them under a microscope. With that experience in
>mind, I've saved a number of chips from junked equipment over the
years.
>
>Has anyone else out there assembled a microscopic chip collection?
>I've thought about removing the dies from the chips (hmm, might
>be tough because they're so fragile) and mounting them on slides.
>
>Sam's message about the 4004 made me think about this. Coulson
>suggested a good way to get a 4004 would be to find one in an old
>cash register. I checked the net for sites for cash register
>repair companies, and sent a few e-mails, but none had spare 4004s.
>
>It would be fun and almost educational to outsiders to have a
>series of slides showing the evolution of the common Intel chipset,
>or memory chips.
>
>- John
>Jefferson Computer Museum <http://www.threedee.com/jcm>
>
>
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