Further to my efforts to free up some room, a smaller item of possible
interest.
A (very) old IMSAI 8080 chassis. Consists of the chassis, IMSAI
backplane, 10amp (point to point wiring) power supply, IMSAI CPU card,
display mask and plexiglass panels. Missing the front panel board, upper
cover, grey switch bezel. (it gave of itself to restore a number of
other machines over the years)
Trades or offers of $$ entertained... (before I give in to the siren call
of ePay... B^} ) For trade suggestions check out the 'Most wanted'
section on the 'Garage' web site.
Have at you!
-jim
---
jimw(a)computergarage.org || jimw(a)agora.rdrop.com
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
>there are 5 RL02 drives sitting at a scrapper in the San Diego area.
>All Computer Surplus 297 S Marshall Ave El Cajun
>Since I am travelling, no time at hand, and furthermore facing the 50 Hz/60 Hz
>problem, I could not do anything about it.
Now I've never used a RL02 drive on 50Hz power, but I'm 99% certain that
the motor speed in a RL02 is determined by a servo loop, and thus
not locked to a multiple of the AC frequency.
I think the fan in a 50Hz RL02 will run a bit slower, but I don't think
this will hurt anything.
The power selector blocks on the back of the drive allow the selection of
90-128VAC or 180-256VAC.
All my (US) RL02 drives have stickers on the back saying "120V, 60Hz",
but I think the voltage is just the factor configuration and the "Hz" is
just an anachronism.
In my RL01/02 books the presence of a 50Hz option isn't even mentioned,
though the tables specify that it's designed for 60Hz power.
If folks know otherwise, they're welcome to correct me!
John G. Zabolitzky
>>There is a picture of the '40 on the website if you want to have a look
>>see...
>So what is above the CPU in the taller picture?
It looks like a paper-tape reader to me, but it may also be a punch -
I can't tell from the tiny little picture.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
I have two problems and 2 Vic20s.
1. My uncle had a vic20 ALONG time ago wich I just recently found. When I pluged it in and turned it on "Let there be light!" A big blue flash appeared and I think the fuse blew. Is there any paticurlar fuses that it uses?
2. My other Vic20 works "ok" But when I load a cart it does not start up right away. How do
I load a cart? I know LOAD "*",8,1 is for disks. But whats for carts?
Thanks..
Sorry if this posts twice for some reason I cant post with my other email address.
Jester
MOVing back into the season of hiding out in the 'Garage' to work on
winter projects, the Garage seems a bit more space constrained than makes
for a comfortable working area, so a bit of redistribution may be in
order. To that end:
Available: (2) PDP-11/40 CPUs. When I acquired them the intent was for
one unit to be restored with the other as a spare/backup/parts unit. Both
are currently in standard six foot tall DEC corporate racks, although only
one of the racks is offered in this deal.
Functional condition of both units is unknown. I did some work on the
primary CPU a couple of years ago and it seemed (at the time) to be
reasonably coherent, but since it has set idle for a year or so, no
promises.
Both are reasonably outfitted, lots of backplane space and cards. And no,
I don't recall what all is there right off hand. For someone SERIOUSLY
interested in obtaining the units I will take a look.
They really should go as a pair, but under the proper circumstances I
could be convinced otherwise...
How much? Well... that one is open for discussion... Trades are always
interesting, for ideas check the 'Most Wanted' list on the 'Garage'
website. For those offering green? I'm listening...
Getting them from here to there? That's up to you... I'll help extract
them from the Garage, but from that point 'yer on yer own...' B^}
There is a picture of the '40 on the website if you want to have a look
see...
Let the games begin!
-jim
---
jimw(a)computergarage.org || jimw(a)agora.rdrop.com
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
>> Now I've never used a RL02 drive on 50Hz power, but I'm 99% certain that
>> the motor speed in a RL02 is determined by a servo loop, and thus
>> not locked to a multiple of the AC frequency.
>>
>> I think the fan in a 50Hz RL02 will run a bit slower, but I don't think
>> this will hurt anything.
>Motor speed is controled by line mains freq. I think the 50hz unit has
>a differnt spindle size. I havent looked under one in 15 years.
What you say certainly describes the RK05, lots of 8" floppy drives
with AC-drive motors and belts, and many other 14" disk drives,
but I'm now 99.44% certain that there's a servo loop for motor speed
regulation in a RL02 and that it's not tied to having a mathematical
relationship of pulley sizes or the AC line frequency.
In fact, my "RL01/RL02 Disk Drive Maintenance Course" textbook says:
The circuits controlling the drive motor in line are
located on two modules. The drive logic module
decodes the speed of the rotating spindle and sends
the signals to the AC servo module which controls
the drive motor's duty cycle.
The disk speed control portion of the DLM monitors
the sector pulse that is created from the reluctance
pick-up and shaped by the circults on page DL6. This
shaped sector pulse, called sector detect, and the
clock from the interface logic are used by the
counting logic to determine how much time is elapsing
between sector pulses. The result is a
signal called Control Speed-up, which is sensed by
the AC servo module. When active, it increases the
duty cycle of the drive motor from 20% to 60%,
speeding up the cartridge. If the disk is within
the speed limits., Control Speed-up is negated, allowing
the drive motor to run at a 20% duty cycle.
This indicates that the master clock setting the drive rotation rate
comes from the interface board in the Q-bus/Unibus/Omnibus (I believe
this is in turn derived from a crystal oscillator), and that
it is not directly tied to the AC line frequency. Indeed, if you
put a not-RL01 or not-RL02 pack in a RL drive and try to spin it up,
the fact that the sector gaps aren't present in the same number means
that it'll spin up to a different speed than if you have a real RL pack
in the drive.
There may be a separate "50Hz" RL drive variant, but I've not seen any
indication of its existence here in North America, in parts lists,
user's manauls, or in maintenance guides. I'm sure some of our
more international members will have better information than I do.
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927
Jay wrote:
> Is there something wrong with the list?
>
> A) It's unusually quiet
> B) I've recently seen people talking about messages I'm fairly certain I
> never saw
> C) I suspect one or two of my messages never went out
>
> Just testing.....
Quiet? I wouldn't say that. This week it's been at sixty or seventy messages
per diem, about twice what it was last week. Not up to the hundred or more that
we sometimes observe, thankfully...
Philip.
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Hi all,
does anyone collect IBM manuals from the mainframe line, like
system /360, or even older ones, like 1140, 1401, 7090, and earlier ?
I would be particularly interested in any hardware docs.
Thanks and regards
John G. Zabolitzky
Well I think the bids on PDP 8s will finally tone down on EBay. The guy that
paid $1300 for the case needed it because he had CPU boards. He bid $300 on
my boards and placed ANOTHER 7 bids in the last 15 miniutes to make sure he
would not get snipered under $1000 for them. It looks like he really wants
to run a PDP 8/e. But... I see this morning someone put up a PDP 8e doc set
on EBay so I wonder how many $100s he will pay for that.
Now that he has what he wanted it looks like the 8 stuff will sell for the
usual $500 or less on EBay.
P.S. If someone put up a Desktop Honeywell 716 on EBay I would probably do
the same thing.
john
-----Original Message-----
From: Kevin McQuiggin <mcquiggi(a)sfu.ca>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Thursday, October 14, 1999 2:00 AM
Subject: Re: collectors vs. enthusiasts
>At 05:14 PM 99/10/13 -0600, you wrote:
>>I think we are seeing some of the same thing in computers,
>>and eBay (and other auction sites) make it easy for them.
>>Hopefully this is just a passing fad. If enough of these
>>"investors" get burned they may not return.
>
>For what it's worth, I'm also an enthusiast/collector of old radios from
>the 1920s and 30s, and eBay has caused the same thing to happen with prices
>in that realm. Old radios and speakers are changing hands at values far
>above what they're actually "worth", based on the number still in
>existence, the technologies used, etc.
>
>This cost craziness has even spilled over into the local secondhand/antique
>market, where radios that used to be fairly priced at say $100 are now
>price tagged at say $400-$500.
>
>I think that speculation on eBay has caused prices to rise artifically, to
>the detriment of those who seek to acquire for love of the technology and
>the fun of getting old radios (or old computers) working again. These
>things are significant parts of history that will be lost unless some folks
>care enough to preserve them.
>
>Kevin
>
>
>---
>Kevin McQuiggin VE7ZD
>mcquiggi(a)sfu.ca
>
