Re: [cosmacelf] Re: My latest elf2k in a case project
- On 12/31/2012 9:21 PM, David Keith wrote:
> I have been wanting to build a working mocked up version of an IBM 370/148That would be interesting! Perhaps the easiest way is to take a good
> Mainframe front panel to hang in my office wall, but lack the artistic
photograph of the front panel, and make a color print of it. Cut holes
for the various lights and switches, and install them.
> Lee Hart's reference to his EV web site, blew me away...Thanks! It's a *big* project, and we've been at it for about 5 years now.
> I was researching how to build an EV bicycle. The bike trail I use to ride, aligned with some high voltageI don't think there's a chance of getting a shock from it. The main
> power lines, and I was trying to figure out how to use my bike frame
> (with a coil of wire) to tape off enough power to drive my 10 speed. LOL
> Thank God I didn't do it, it would have been a very shocking experience
problem is that the power lines are normally well balanced, to minimize
radiated power. Thus there is little or none to be picked up.
The power companies always strive to run equal and opposite currents in
the wires. The radiated fields from them cancel out once you are more
than a few times the spacing between the wires away from them. It's
called "transmission line theory" if you want to study up on it.
But once in a blue moon, they'll screw up. If the currents are *not*
equal and opposite, you *can* make an air-core transformer with your own
wires at ground level. The efficiency is poor (due to the air core at
60hz), but who cares if they loose 100 watts for every watt you receive. :-)
In one famous case, a power company installed a set of high power lines
over a farm. The farmer kept complaining that he was getting shocks, the
lights in his barn would light even with the switch off, etc. The power
company refused to take him seriously. So he strung up a big loop of
wire under the power lines, and used the power received to run everything.
Now, the power companies have meters to measure how much power is going
out on a line, and how much is being received at the other end. It's
intended to detect damaged insulators, loose connections, trees on the
wires, etc. His power draw drove them nuts, because they couldn't find
the source of the leakage! They eventually figured it out, re-balanced
the lines, and the power loss went away.
> But seriously guys, why don't we channel all this creative energy into aI think many of us design and build things for fun; not for profit. I
> new product the group can sell as a kit or as assembled. Guys think
> outside of the box (case )
know I do. There really isn't a market for most of these things. People
want *cheap*, not clever -- and no hand-made low-production item can
compete with the cheap flashy stuff from China, India, Mexico, etc.
Take my Membership Card, for example. It costs $79, because sales volume
is so low (I sell about 1 a week). But you can buy an Arduino for $29,
because they sell a *thousand* a week. With that kind of sales volume,
they can build them in China to get the price down, hire a staff of
people to do development and sales promotions, etc. They have so many
customers that there is a lot of "buzz" on the web to use it, further
promoting sales. (Look at the Hack-a-day website, where it seems like
every other project uses an Arduino).
It's HARD to think of things that people will actually BUY for more than
it costs you to make it. So you do it for fun; not profit.
Don't worry about people stealing your ideas. If your ideas are any
good, you'll have to ram them down people's throats. -- Howard Aiken
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm
- Thanks Craig,I see you are right. I keep on forgetting that the System 370 ISA is/was not a physical architecture, but one that was emulated in the mircocode/programming of the underlying model hardware. Looks like 370/138 model was actually a 16 bit word, with only a maximum addressable memory of 1 mega bytes.Good CatchDave
From: cstull <cstull@...>
To: David Keith <beloved_wind@...>
Sent: Monday, February 18, 2013 3:03 PM
Subject: Re: My latest elf2k in a case project
I think you are mistaken on the 370/138 control panel. If you go to images.google.com and type in IBM 370/138 you will see that the item that was on ebay is identical to the 138 panel. The 3705 panel doesn't look at all like it.
The 138 must have been a shorter address machine because with five hex knobs to address memory, that would mean that the maximum addressable memory (FFFFF) would have been 1 meg.
Lots of iron for a 1 meg machine.
--- In firstname.lastname@example.org, David Keith <beloved_wind@...> wrote:
> Thanks Bill, glad to see some old time mainframe system 370 programmers still out there. I am aware of the Hercules 370 emulator, but never have/had the time to download it and play with it.
> Found this link for a IBM System 370 control panel for sell out on eBay, BUT it looks like someone took a IBM 3705 Communications Controller and fit it to be a 370/138 console. NOT enough lights (16 bits + 2 parity) when there should be 32 bits + 4 parity, also not enough rotary selection switches at the bottom. Very good conversation piece, LOL