28 ms·

Forgive me, but I'm struggling to understand how much useful work one could extract from a computer with only 32k of RAM. A microcontroller for an appliance, su

Forgive me, but I'm struggling to understand how much useful work one could extract from a computer with only 32k of RAM. A microcontroller for an appliance, sure, but a mainframe? Could you tell us more about the work you were doing?

TylerE 8y ago
Oblig NASA factoid: The guidance computer on Apollo that got as to the moon had 4096 bytes of RAM and about 72K of ROM.
- cylinder714 8y ago
  Whew, excellent point. That raises another question, though—how much computational work did that computer have to do? The real heavy lifting was performed by big NASA mainframes on Earth, right?
  - cbm-vic-20 8y ago
    The Apollo computer did things like control rocket burns, provide navigational information, etc. More information http://nassp.sourceforge.net/wiki/Guidance_and_Control_System http://nassp.sourceforge.net/wiki/Guidance_and_Control_Syste... The source is on Github, too, for example: https://github.com/chrislgarry/Apollo-11/blob/master/Luminary099/BURN_BABY_BURN--MASTER_IGNITION_ROUTINE.agc https://github.com/chrislgarry/Apollo-11/blob/master/Luminar...
cylinder714 8y ago
(An aside: do terms like "mainframe" and "microcomputer" have any meaning any more, when a Raspberry Pi Zero has orders of magnitude greater RAM and power than a '70s piece of "big iron"?)
- joshAg 8y ago
  Yes. Mainframes still exist. IBM still sells them, and you can do things like hotswap CPUs and RAM or setup an geographically distributed HA cluster that can swap which mainframe the VMs or databases are "running" on without dropping connections, requests, or other interruptions. https://en.wikipedia.org/wiki/IBM_Z https://en.wikipedia.org/wiki/IBM_Z
- nineteen999 8y ago
  One of the four large banks in my country I worked at only a few years ago still managed all their internal change management process on a fairly old IBM mainframe. You had to connect via an arcane telnet client (tn3270 protocol perhaps?) and input the change details. No fancy web forms. Perhaps it was a limitation of the application, but you couldn't mix uppercase and lowercase in the one form.
cbm-vic-20 8y ago
You could land a spaceship in the moon with a computer with less RAM. https://en.wikipedia.org/wiki/Apollo_Guidance_Computer https://en.wikipedia.org/wiki/Apollo_Guidance_Computer
- danellis 8y ago
  > with a computer with less RAM And a team of scientists who had done all the difficult calculations beforehand...
wglb 8y ago
In 1970, a company named Telemed built an Electrocardiograph analysis service where hospitals would call in from all around the country and send ECGs over the telephone line with analog FM signals, three channels at a time. The computer located near Chicago would accept the incoming call, digitize the three analog signals every 2ms to 10 bits, write them to disk, and decode the touch-tone patient ID. When the call was completed, the data from disk would be assembled into a full ECG record and written to tape, and simultaneously passed to the diagnostic program written in Fortran. The system would then initiate a phone call to the hospital's printer and print out an English-language diagnostic. The result was then available in ten minutes to the staff a the hospital. The front end and back end was all Sigma 5 (first SDS then Xerox midrange real-time computer) assembler in an interrupt-rich process--one interrupt every 2ms for the analog, one interrupt for the disk write complete, interrupts for the tape record writing, interrupts for the outgoing phone call progress. This included an cost optimization process that would choose which line (this was in the days of WATS lines) based on desired response time. The middle was the Fortran program that would analyze the waveforms, identifying all the ECG wave forms--P-wave, QRS, and T-Wave--the height, duration, sometimes slope. This all took place in a machine with 32k words (four bytes per word). There were two computers, one nominally used for development, but could be hot-switched if the other failed. I think downtime was on the order of an hour per year. This would have been called an Expert System, but I don't think the term was in common use as yet. So the answer to your question is: "A considerable amount". Today we are all spoiled by environments with more memory on one machine than existed in the entire world at that time.
- cylinder714 8y ago
  Thank you, that's brilliant! It is unfortunate that the source code is lost to humanity, as an example of what is possible.
  - tux3 8y ago
    If you want examples of how far you can go packing way too many things in too little code, you may be interested in the demoscene!
  - 8y ago
ehaliewicz2 8y ago
The original gameboy has 8K of RAM and the first and second gen pokemon games run on it. Most of the hard work is done by the graphics and sound hardware. Fairly large games though.
- colejohnson66 8y ago
  The original NES had 2K of RAM (but cartridges could expand that).
zeta0134 8y ago
A key thing to remember is that 32k of RAM isn't the only memory available; often there was all sorts of longer term storage, and in many cases the data for a job was separate than the machine running the program, which could feed that data in using a number of methods. Today's programs load entire files into RAM because it's available; back then you might load a single record from the file at a time, and there were routines to seek through the offline data (subject to optimization) and manage the working memory more effectively. It's also worth remembering that, at the time, a machine with 32k of RAM was one of the most powerful on the market, was still considerably expensive, and the alternative was paying (a team of) humans to do the work by hand. For all its shortcomings and the insane complexity required to get the machines to work properly, they were generally much faster than humans performing the same task and generally (assuming they were programmed correctly) could be relied on to make fewer mistakes. Their utility was remarkable, especially their ability to perform arithmetic very quickly, which was (and still is) quite tedious to perform by hand.
ridgeguy 8y ago
In 1969, a computer with "2048 words of RAM" and "36,864 words of ROM" managed a landing on the Moon and subsequent return[1]. People do amazing things with primitive tools. [1] https://en.wikipedia.org/wiki/Apollo_Guidance_Computer https://en.wikipedia.org/wiki/Apollo_Guidance_Computer
ci5er 8y ago
The PDP (11? I think so, but maybe 7? My home PDP for running the internet in my corner of the universe was an 11) at JPL that processed the Voyager flyby snapshots of Saturn into colorized planet+ring images was 64KB. Instead of viewport-centric geometry scans doing texture lookup, they scanned in texture-space (less swapping)

TylerE 8y ago

Oblig NASA factoid: The guidance computer on Apollo that got as to the moon had 4096 bytes of RAM and about 72K of ROM.

cylinder714 8y ago
Whew, excellent point. That raises another question, though—how much computational work did that computer have to do? The real heavy lifting was performed by big NASA mainframes on Earth, right?
- cbm-vic-20 8y ago
  The Apollo computer did things like control rocket burns, provide navigational information, etc. More information http://nassp.sourceforge.net/wiki/Guidance_and_Control_System http://nassp.sourceforge.net/wiki/Guidance_and_Control_Syste... The source is on Github, too, for example: https://github.com/chrislgarry/Apollo-11/blob/master/Luminary099/BURN_BABY_BURN--MASTER_IGNITION_ROUTINE.agc https://github.com/chrislgarry/Apollo-11/blob/master/Luminar...

cylinder714 8y ago

(An aside: do terms like "mainframe" and "microcomputer" have any meaning any more, when a Raspberry Pi Zero has orders of magnitude greater RAM and power than a '70s piece of "big iron"?)

joshAg 8y ago
Yes. Mainframes still exist. IBM still sells them, and you can do things like hotswap CPUs and RAM or setup an geographically distributed HA cluster that can swap which mainframe the VMs or databases are "running" on without dropping connections, requests, or other interruptions. https://en.wikipedia.org/wiki/IBM_Z https://en.wikipedia.org/wiki/IBM_Z
nineteen999 8y ago
One of the four large banks in my country I worked at only a few years ago still managed all their internal change management process on a fairly old IBM mainframe. You had to connect via an arcane telnet client (tn3270 protocol perhaps?) and input the change details. No fancy web forms. Perhaps it was a limitation of the application, but you couldn't mix uppercase and lowercase in the one form.

cbm-vic-20 8y ago

You could land a spaceship in the moon with a computer with less RAM. https://en.wikipedia.org/wiki/Apollo_Guidance_Computer https://en.wikipedia.org/wiki/Apollo_Guidance_Computer

danellis 8y ago
> with a computer with less RAM And a team of scientists who had done all the difficult calculations beforehand...

wglb 8y ago

In 1970, a company named Telemed built an Electrocardiograph analysis service where hospitals would call in from all around the country and send ECGs over the telephone line with analog FM signals, three channels at a time. The computer located near Chicago would accept the incoming call, digitize the three analog signals every 2ms to 10 bits, write them to disk, and decode the touch-tone patient ID. When the call was completed, the data from disk would be assembled into a full ECG record and written to tape, and simultaneously passed to the diagnostic program written in Fortran. The system would then initiate a phone call to the hospital's printer and print out an English-language diagnostic. The result was then available in ten minutes to the staff a the hospital. The front end and back end was all Sigma 5 (first SDS then Xerox midrange real-time computer) assembler in an interrupt-rich process--one interrupt every 2ms for the analog, one interrupt for the disk write complete, interrupts for the tape record writing, interrupts for the outgoing phone call progress. This included an cost optimization process that would choose which line (this was in the days of WATS lines) based on desired response time. The middle was the Fortran program that would analyze the waveforms, identifying all the ECG wave forms--P-wave, QRS, and T-Wave--the height, duration, sometimes slope. This all took place in a machine with 32k words (four bytes per word). There were two computers, one nominally used for development, but could be hot-switched if the other failed. I think downtime was on the order of an hour per year. This would have been called an Expert System, but I don't think the term was in common use as yet. So the answer to your question is: "A considerable amount". Today we are all spoiled by environments with more memory on one machine than existed in the entire world at that time.

cylinder714 8y ago
Thank you, that's brilliant! It is unfortunate that the source code is lost to humanity, as an example of what is possible.
- tux3 8y ago
  If you want examples of how far you can go packing way too many things in too little code, you may be interested in the demoscene!
- 8y ago

ehaliewicz2 8y ago

The original gameboy has 8K of RAM and the first and second gen pokemon games run on it. Most of the hard work is done by the graphics and sound hardware. Fairly large games though.

colejohnson66 8y ago
The original NES had 2K of RAM (but cartridges could expand that).

zeta0134 8y ago

A key thing to remember is that 32k of RAM isn't the only memory available; often there was all sorts of longer term storage, and in many cases the data for a job was separate than the machine running the program, which could feed that data in using a number of methods. Today's programs load entire files into RAM because it's available; back then you might load a single record from the file at a time, and there were routines to seek through the offline data (subject to optimization) and manage the working memory more effectively. It's also worth remembering that, at the time, a machine with 32k of RAM was one of the most powerful on the market, was still considerably expensive, and the alternative was paying (a team of) humans to do the work by hand. For all its shortcomings and the insane complexity required to get the machines to work properly, they were generally much faster than humans performing the same task and generally (assuming they were programmed correctly) could be relied on to make fewer mistakes. Their utility was remarkable, especially their ability to perform arithmetic very quickly, which was (and still is) quite tedious to perform by hand.

ridgeguy 8y ago

In 1969, a computer with "2048 words of RAM" and "36,864 words of ROM" managed a landing on the Moon and subsequent return[1]. People do amazing things with primitive tools. [1] https://en.wikipedia.org/wiki/Apollo_Guidance_Computer https://en.wikipedia.org/wiki/Apollo_Guidance_Computer

ci5er 8y ago

The PDP (11? I think so, but maybe 7? My home PDP for running the internet in my corner of the universe was an 11) at JPL that processed the Voyager flyby snapshots of Saturn into colorized planet+ring images was 64KB. Instead of viewport-centric geometry scans doing texture lookup, they scanned in texture-space (less swapping)