Linked by Thom Holwerda on Wed 28th Jun 2017 19:28 UTC
Hardware, Embedded Systems

Last week I wrote a Mandelbrot set program for the Xerox Alto, which took an hour to generate the fractal. The point of this project was to learn how to use the Alto's bitmapped display, not make the fastest Mandelbrot set, so I wasn't concerned that this 1970s computer took so long to run. Even so, readers had detailed suggestions form performance improvements, so I figured I should test out these ideas. The results were much better than I expected, dropping the execution time from 1 hour to 9 minutes.

Articles like this are very satisfying to post, because we can all agree this is just plain awesome, no ifs or buts.

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RE: Manual
by jockm on Thu 29th Jun 2017 05:01 UTC in reply to "Manual"
jockm
Member since:
2012-12-22

I was surprise that there was no "OR" function in the CPU.


Well one could be added to the microcode store, and there were alternate microcoded instruction sets for the Alto and D-Machines that did include OR; it was just that the default DG Nova compatible microcode didn't include it.

Reply Parent Score: 2

RE[2]: Manual
by avgalen on Thu 29th Jun 2017 08:03 in reply to "RE: Manual"
avgalen Member since:
2010-09-23

Well one could be added to the microcode store, and there were alternate microcoded instruction sets for the Alto and D-Machines that did include OR; it was just that the default DG Nova compatible microcode didn't include it.

This comment should be send to every developer on every locked down platform so they realize just how different their current solutions to problems are from the past.
While they chew on that they can be served a bit of desert in the shape of "how Compaq reverse engineering of the IBM-PC BIOS started the general computing area for the masses"

Reply Parent Score: 2

RE[3]: Manual
by jockm on Fri 30th Jun 2017 02:59 in reply to "RE[2]: Manual"
jockm Member since:
2012-12-22

Well most computers at that time didn't have a writable microcode store. But it is also important to remember that that flexibility came at a price.

Intel and AMD implement a CISC instruction set on top of a hidden RISC microarchitecture. Microarchitectures can be seen as the modern equivalent of microcode

Reply Parent Score: 2