Is there anyone in the Tampa area that's interested in helping out with a
computer rescue?
Please reply privately <sellam(a)vintage.org>.
Thanks!
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
Hello,
I have been looking for a DEC TC11 tape controller to go with my
PDP11/45 and TU56 tape drives for some time now. I just discovered
this mailing list, so now I am trying here.
Is there any chance that anyone has a TC11 for sale or trade?
Also, I am looking for a pair of DEC H960 (72") rack sides, preferably
>from someone in the Chicago area.
Thanks in advance (there is always a hope:-)
--tom
> My first useful program was a graphical alarm clock. I'm a dropout and so
> missed math education beyond arithmetic. This is why I do all my agebraic
> problems linearly as you do in programing. I still don't understand how
> and why algebra is done the way it is in schools. Boolean algebra makes
> so much more sense to me.
Trig smoothly describes the world as it really is-
the approximations you independently discovered describe the
world well enough to fool human perception.
More on this below.
> Anyway, I was trying to plot the face of a circular clock. First I tried
> using PI as the base for the plotting and my clock's face came out wierd
> and incomplete. After messing with the program for some hours I realized
> that OF COURSE a circle derived from pi was going to be incomplete because
> PI is irrational. No matter how many digits after the dicimal you use, you
> will never get a complete circle, just a progressively less incomplete
> one. Duh. Back to the drawing board.
>
> I started hitting the trig functions looking for an answer and hit on
> Sine/cosine as the way to do it. Educating yourself is hard and you often
> have to backtrack like that.
You only have to look at AutoCAD to see how crappy a circle looks when
derived by trigonometric evaluation; it wouldn't be that way if there was
enough precision available, but there never seems to be...
So, a guy named Bresenham came up with a click way to generate a circle,
and it was improved upon by another computer scientist named Michener.
it takes advantage of the 8-way symmetry a circle will have when created
in the approximate fashion that pixels arranged in a Cartesian grid yields.
The algorithm generates the points for a single octant of the circle, then
generates the other seven octants by (essentially) changing the sign of
the values for the first octant. The virual result are perfectly symmetric
approximations of circles.
There's also an algorithm I saw written up in Byte years ago for doing
parabolas; the author referred to it as the Variable Duty-Cycle Algorithm.
For a dummy radar-display I hacked up, to handle the sweep line, I
simply at program start-up pre-computed all the data for the lines
in each position of the sweep; I did it with trigonometric evaluation,
but stored the daata in an array and just puked it out at runtime.
But just like with the calculator, it helps to understand the
fundamentals before trying to implement a solution sans science.
OTOH, not knowing the fundamentals has failed to stop many a man...
...OOPS! And women, too, I guess (apologies to Megan and Allison!).
Regards,
-dq
All,
The e-address for this system, rmays(a)satx.rr.com, sounds a lot like
it's in my home town, San Antonio. If that's true and you need help moving,
shipping (eek), putting in a UHaul and meeting you somewhere in central
Texas, etc., email me and I'll pitch in. I'm not interested in the system
for myself.
- Mark
I have a portable test set by Data Disk Inc. of Sunnyvale CA that is
identified as an "8000 Series Exerciser". It comes in a molded case
with handle and removable lid that is 14"W x 10.5"D, and 7"H. It is
powered from a fixed 3-conductor line cord by 115 +/- 10% VAC at
47-400Hz. The unit dates to late 1974 according to the panel
information drawing taped to the inside of the lid. Also, users are
enjoined to "be kind to this tester its a one & only" according
to a label stuck onto the inside of the lid. It could well be as it is
entirely wire wrapped.
The panel contains several rows of mini-toggle switches to select
tracks from 1-512, a 16-bit data pattern, modes of testing, power, etc.
Also a four wheel indicating rotary switch to set bits/sector.
External connections are a 50-conductor ribbon cable that is terminated
in an edge connector (50-pin), and a row of banana jacks to permit
bringing out 8 functions for scope display.
It is available for the price of shipping to anyone who wants it.
I'm guessing that it weighs about 10 pounds.
- don
As folks who follow this list may recall, I was asking about a month ago if
anyone had any vacuum sensors for a TU10.
Since that time, I have identified a source for purchase of these sensors
(set for 10" H2O pressure). They are suitable for TU10's (where I found
some of the exact part I found in there as replacements) and for the DG
6021. I would guess that they are in other drives of similar vintage. (a
TU10 has 8 of them, a 6021 has 4 of them (plus a separate 20" H20 unit) )
If you have a TU10 or a DG 6021, and expect to keep it running for another
10 years, listen up: these will fail, eventually, depending on what their
condition was when you got the drive, how often you use it, etc. On the
TU10, the ones most likely to fail are at the bottom of each vacuum column,
because they are in a pressure differential state most of the time.
I can get the parts for $14.23 each in unit quantities, but the catch is
that the minimum order is $250. I was thinking that I needed about 10 of
them, for sure, so I'd like to find someone else who could use at least 7
or 8 of them.
I also suspect that the price would come down a little for quantities over
24 -- but I have not yet checked quantity pricing.
SO, what I would like to do is this. Anyone who is SERIOUSLY interested in
purchasing some of these beasties, please reply to me (as well as or
instead of the list), and I'll try to put an order together this
month. Payment will probably be via your choice of personal check or
PayPal (I have not yet set up my PayPal account, though).
Jay Jaeger
---
Jay R. Jaeger The Computer Collection
cube1(a)home.com visit http://members.home.net/thecomputercollection
John Tinker has just claimed this item.
- don
---------- Forwarded message ----------
Date: Mon, 15 Jan 2001 17:09:10 -0800 (PST)
From: Don Maslin <donm(a)cts.com>
Reply-To: classiccmp(a)classiccmp.org
To: classiccmp(a)classiccmp.org
Subject: Garage cleaning
I have a portable test set by Data Disk Inc. of Sunnyvale CA that is
identified as an "8000 Series Exerciser". It comes in a molded case
with handle and removable lid that is 14"W x 10.5"D, and 7"H. It is
powered from a fixed 3-conductor line cord by 115 +/- 10% VAC at
47-400Hz. The unit dates to late 1974 according to the panel
information drawing taped to the inside of the lid. Also, users are
enjoined to "be kind to this tester its a one & only" according
to a label stuck onto the inside of the lid. It could well be as it is
entirely wire wrapped.
The panel contains several rows of mini-toggle switches to select
tracks from 1-512, a 16-bit data pattern, modes of testing, power, etc.
Also a four wheel indicating rotary switch to set bits/sector.
External connections are a 50-conductor ribbon cable that is terminated
in an edge connector (50-pin), and a row of banana jacks to permit
bringing out 8 functions for scope display.
It is available for the price of shipping to anyone who wants it.
I'm guessing that it weighs about 10 pounds.
- don
Since we had some talk about NetBSD, this is totally off-topic, not to
mention totally bizarre. And it really does exist.
http://www.netbsd.org/Ports/dreamcast/
--
----------------------------- personal page: http://www.armory.com/~spectre/ --
Cameron Kaiser, Point Loma Nazarene University * ckaiser(a)stockholm.ptloma.edu
-- I can't complain, but sometimes I still do. -- Joe Walsh -------------------
--- David Gesswein <djg(a)drs-esg.com> wrote:
> Does anybody happen to have a spare one of these? I have a AT&T
> 5620 terminal missing the mouse and I think that is the one that goes with
> it. Terminal has a DB-9 connector.
>
> > It is bright red, almost perfectly round,
I do. Anyone with a naked 5620 terminal, contact me off-list for a mouse. I
have more than one, but I cannot test them. Anyone want to swap a few mice
for a spare terminal? I also have a couple of ROM carts that I think are for
them (the one in my hand has a damaged label that reads, in part "...456
615MT/4425 emulation and has three 27128 unlabelled EPROMs and a few TTL parts;
somewhere, I may still have a couple of carts with some 27C512s, but I've been
recycling the EPROMs from those so I don't know if I have any left)
-ethan
=====
Even though my old e-mail address is no longer going to
vanish, please note my new public address: erd(a)iname.com
The original webpage address is still going away. The
permanent home is: http://penguincentral.com/
See http://ohio.voyager.net/ for details.
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