12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
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Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#2Way back in 1985, a seminal 'Computer Recreations' column in Scientific American featured the Mandelbrot set: https://www.scientificamerican.com/media/inline/blog/File/De...
(A K Dewdney's columns were always fantastic - a whole new world of wonder for early 'home computer' users!)
After careful study, my brother coded it in assembly on a C64. We both had the idea to double the display resolution (from 320x200 to 640x400) by 'extending' the screen into RAM. After leaving the computer running overnight (often longer), we eagerly came the next day to check progress, and dump the output to a dot matrix printer. We couldn't use color or even grayscale, so black and white stripes were the only option to reveal the glories of the Mandelbrot set.
Result: stunning, finely detailed, black and white images! I still have the printouts...
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#3The footnotes in this article are fantastic.
I used the inflation calculator [1] to convert 1960s prices to today's dollars:
- Rental price: ~$20,000 / month
- Purchase price: ~$1,000,000 (yes, a million dollars).
So what you're looking at is what used to be a million dollar computer. You could buy a car for every month you pay to use this machine, so you better had really useful programming ideas or it's back to pen & paper :)
As the author points out, this was considered the model T of computers because of how affordable it was compared to what sold before.
The attention to detail is tremendous.
I never paid much attention to the design of old IBM mainframes, but now I can see how profoundly it influenced our perception of computing. I love the author's phrase "inherent drama of computing." and how it became a trope. The IBM industrial design book [2] he recommends is now going on my to-read list..
[1] http://www.usinflationcalculator.com/
[2] The Interface: IBM and the Transformation of Corporate Design http://www.amazon.com/gp/product/0816670390/ref=as_li_tl?ie=...
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#4This is fascinating. While I have a soft spot for old computers, I don't think I would put that much time into such a project. I do admire the author's determination, though! I imagine it must have been a lot of fun and thoroughly enjoyed reading about it.
Just the other day, I was talking to one of our automation engineers on the phone, and while waiting for his computer to reboot, we talked about old hardware. He told me how, as a student, he sometimes had to write programs in FORTRAN, and how punched cards were kind of, eh, expensive[1], so the students were all kind of happy when somebody hooked up a paper tape reader to the university computer. Until, that is, they realized that paper tape - at least the paper they were using - was kind of prone to tear, and sometimes students would get their programs back in pieces.
I feel nostalgic about this era I did not see for myself, but I also appreciate today's computers being cheap and - for most intents and purposes - mind-bogglingly fast.
EDIT: Also, it is fascinating how the 1401 was simple enough that one could get to know each part of it so intimately, from the software running down to the individual pieces making up the processor. On today's computers, where even the keyboard controller is probably more complex than the entire 1401, this has become pretty much impossible.
[1] This engineer is from Eastern Germany, and I know that, for example, audio tape was fairly expensive over there. But punched cards, made out of paper? And keep in mind, this must have been at least around 1980!
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#5Way back in 1985, a seminal 'Computer Recreations' column in Scientific American featured the Mandelbrot set: https://www.scientificamerican.com/media/inline/blog/File/De... (A K Dewdney's columns were always fantastic - a whole new world of wonder for early 'home computer' users!) After careful study, my brother coded it in assembly on a C64. We both had the idea to double the display resolution (from 320x200 to 640…
I loved AK Dewdney's columns. The Core War [1] columns influenced me profoundly.
Would love to see the mandelbrot printout scans :)
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#6Way back in 1985, a seminal 'Computer Recreations' column in Scientific American featured the Mandelbrot set: https://www.scientificamerican.com/media/inline/blog/File/De... (A K Dewdney's columns were always fantastic - a whole new world of wonder for early 'home computer' users!) After careful study, my brother coded it in assembly on a C64. We both had the idea to double the display resolution (from 320x200 to 640…
I learned about the set in '87 or '88 and wrote a BASIC program to calculate it on my Apple IIe using the "obvious" algorithm.
I left my computer on overnight (I had no idea if it would overheat). However, even after a day, it hadn't even got to the interesting parts of the set- it was still off in the big bands of constant color around the set.
When I got to college I had a PC (a 286 with no floating point hardware) so I ran FRACTINT. It was great, fast, and fun. Eventually PCs got hardware floating point but by that time, few people were really exploring fractals.
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#7The footnotes in this article are fantastic. I used the inflation calculator [1] to convert 1960s prices to today's dollars: - Rental price: ~$20,000 / month - Purchase price: ~$1,000,000 (yes, a million dollars). So what you're looking at is what used to be a million dollar computer. You could buy a car for every month you pay to use this machine, so you better had really useful programming ideas or it's back to pen…
I'm glad someone reads my footnotes :-). About the rentals - most customers rented instead of buying. This had a huge effect on computer companies. Starting a competitor was extremely capital intensive since you had to build the computers up front and then you got revenue monthly, rather than from big sales. Rentals also made IBM conservative since they didn't want to introduce a new machine that would obsolete all the old ones they were still renting out.
As for the design book, I only recommend it about 50% - it has a lot of academic theory that HN readers may find uninteresting. It also goes into great detail of the architecture of IBM buildings. Not to discourage you but just set expectations.
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#8This article and its footnotes constitute the best summary of an IBM mainframe computing environment I have ever encountered. Have occasionally tried to read the old reference materials but they were never remotely this cogent. He also makes good use of modern context, since we have now settled on fundamentals such as word length, binary encoding, and so on. A masterpiece in miniature.
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#9I worked as a paid programmer on card systems in 1970. I'm not saying things were better then. Give me C++ and Python any day over Assembler.
However, there was something magical about being able to step through your program one instruction at a time using a switch on the control panel, or being able to display and modify the memory with lights & toggle switches. It was like you were reaching right into the soul of the machine, in a mysterious world.
Compilations were so expensive (40 min. for a 4,000-card program) that we would often patch the binary card decks to squeeze one more test.
We had to segment our programs into "overlays" that would load consecutively, and re-use the same limited memory locations. What a pain :o)
Having dealt with index registers in Assembler, C pointers were a cinch.
Re: 12-minute Mandelbrot: fractals on a 50 year old IBM 1401 mainframe
#10The footnotes in this article are fantastic. I used the inflation calculator [1] to convert 1960s prices to today's dollars: - Rental price: ~$20,000 / month - Purchase price: ~$1,000,000 (yes, a million dollars). So what you're looking at is what used to be a million dollar computer. You could buy a car for every month you pay to use this machine, so you better had really useful programming ideas or it's back to pen…
I'm glad someone reads my footnotes :-). About the rentals - most customers rented instead of buying. This had a huge effect on computer companies. Starting a competitor was extremely capital intensive since you had to build the computers up front and then you got revenue monthly, rather than from big sales. Rentals also made IBM conservative since they didn't want to introduce a new machine that would obsolete all t…
We employ z, i, and p, series systems from IBM currently. The biggest costs these days have become licensing software and site costs; power, cooling, site to site comm, and space. The number of languages used across all platforms is varied and well represented. There will always be a lot of business use for large hardware and even languages I thought long past their prime have had enough enhancements they blend the best of the old coding with the newest.