5 ms·

Dijkstra told similar stories. Working in the immediate post-war Netherlands he got something like 30 minutes of machine time a week. I may be wrong on the exac

by User23 2y ago

Dijkstra told similar stories. Working in the immediate post-war Netherlands he got something like 30 minutes of machine time a week. I may be wrong on the exact amount of time, but it was extremely limited. I believe that, at least until recently, quite a lot of the continental European approach to computing science was due to the culture those early pressures created.

cardiffspaceman 2y ago
In the USA, in the ‘70’s, I had an account on a university computer that was good for 4 hours in a month. I think that was just a fairly normal thing in the old days, when almost nobody had an Apple ][.
- kragen 2y ago
  also, i think it's a pretty large amount of computer time! it was enough to do things every month that would have required decades or centuries with a pocket calculator if you were using an ibm 370 model 168 http://www.bitsavers.org/pdf/ibm/370/funcChar/GA22-7010-4_370-168_funcChar_Jul76.pdf http://www.bitsavers.org/pdf/ibm/370/funcChar/GA22-7010-4_37..., you were running on a machine with 1 to 8 mebibytes of ram (dedicated entirely to your program if in batch mode), 16 mebibytes of virtual memory, an l1 cache which i think was 8 kibibytes by default, 1.3 megabytes per second of i/o per channel (with up to 12 channels), and a fixed-point (32-bit) multiply took 780 nanoseconds, so you could do about 1.3 million multiplies per second. your data would often be on magtape, which moved 2.9 meters per second, which would be 700 kilobytes per second at 6250 characters per inch (introduced 01973). 4 hours would be 18 billion multiplies the apple ][, by comparison, could have 64 kibibytes of ram, and read or write a floppy at about two kilobytes per second and run about 300'000 instructions per second, delivering 0.021 dhrystone mips on an apple //e, according to https://netlib.org/performance/html/dhrystone.data.col0.html https://netlib.org/performance/html/dhrystone.data.col0.html. so, coming at it from a batch processing perspective, this particular 370 model had about 64 times as much ram as a maxed-out apple ][, about 64 times as much computing power (maybe 1024× for floating-point stuff), and i/o on the order of 2048 times faster so those 4 hours of computer would allow you to process a quantity of data on magtape that would take about a year swapping floppies on an apple ][, or do an amount of calculation the apple would need weeks or months for suppose instead of the apple your alternative was an hp-35 non-programmable pocket calculator, introduced in 01972, or more or less equivalently, a slide rule. you need about 2 seconds to enter each new operand and press an operation key. we can derate those 18 billion multiplies in the 4-hour monthly allocation to about 5 billion total operations if we include cosines, square roots, etc. this would take you 300 years to do by hand on the hp-35. on a programmable hp-65 (introduced 01974) maybe only 30 years the enormous benefit of the apple ][ was that you got millisecond turnaround instead of hundred-kilosecond turnaround. for many purposes, those eight orders of magnitude less latency more than compensated for the two or three orders of magnitude you were sacrificing in throughput when i started using time-shared unix machines in the 01990s (according to the dhrystone link, the decstation 3100 was 13.4 dhrystone mips, so roughly 16 times the mainframe described above) i would log into a shell server with 16-64 other concurrent users. the default cpu time limit was, i think, 10 minutes. that is, when you launched a program, if it used 10 minutes of cpu, the os would kill it. before netscape, the only time i ever saw this happen was when i accidentally wrote infinite loops. i could use an interactive program like trn or tcsh or emacs for hours and hours without hitting that limit
  - kragen 2y ago
    looking at the docs for the ibm 370 model 165 (https://bitsavers.org/pdf/ibm/370/systemGuide/GC20-1730-0_370-165_Guide_Nov70.pdf https://bitsavers.org/pdf/ibm/370/systemGuide/GC20-1730-0_37... from 01970, several years before the model 168 mentioned above) i came across these more detailed notes on cpu performance > The CPU has an 80-nanosecond cycle time and an 8-byte-wide data path. (...) Among the major elements in the CPU are the instruction unit, the execution unit, local storage, and control storage. > (...) The faster internal performance of the Model 165 is due in part to the use of more concurrence in CPU operations than is implemented in the Model 65. The Model 165 CPU contains an instruction unit and an execution unit that overlap instruction fetching and preparation with instruction execution. The Model 165 instruction unit is controlled by logic circuits and can process several instructions concurrently while the execution unit is executing a single instruction. The instruction unit prefetches instructions (maintaining them in sequence), decodes instructions, calculates addresses, prefetches instruction operands, and makes estimates of the success of conditional branches. When a conditional branch is encountered, the instructions immediately following the branch and those located at the branch address are prefetched and placed in separate instruction buffers within the instruction unit. Two 16-byte instruction buffers are used. This insures the availability of prefetched instructions whether the branch is taken or not. > The execution unit is microprogram controlled and can execute one instruction at a time. It has the capability of processing a new instruction every cycle. Emphasis is placed on optimizing fixed binary and floating-point arithmetic operations. A 64-bit parallel adder is used to perform binary and floating-point arithmetic, while an 8-bit serial adder is used in the execution of packed decimal arithmetic. processing a new instruction every 80-nanosecond cycle would be a peak performance of 12.5 mips, although presumably many instructions, in particular including multiplication, apparently took longer than that; i think the average was over 2 cycles per instruction. the 12.5 megahertz clock was the same on the model 168 i described above i'm not an ibm fan. but ibm mainframes might be the central example of 'the kind of large computer a person at a university in the 01970s might be allocated a few hours a month on' there's a wikipedia article about this particular model, mentioning it was discontinued in 01977: https://en.wikipedia.org/wiki/IBM_System/370_Model_165 https://en.wikipedia.org/wiki/IBM_System/370_Model_165 there's a table at the end of https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Papers/Padegs-IBM360-sep81.pdf https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Pape... describing the clock speed, cache size and associativity, cache line size, tlb size, etc., of numerous 360 and 370 models, including the 165 and 168, unfortunately lacking year of introduction. if someone else is doing this kind of investigation they may find it a useful reference ken shirriff has an overview of the 360 line at http://www.righto.com/2019/04/iconic-consoles-of-ibm-system360.html http://www.righto.com/2019/04/iconic-consoles-of-ibm-system3... nyt published an article on the introduction of the model 165 at https://www.nytimes.com/1970/07/01/archives/ibm-shows-2-new-computers-ibm-shows-2-new-computer-models.html https://www.nytimes.com/1970/07/01/archives/ibm-shows-2-new-... ('i.b.m. shows 2 new computers', gene smith, 01970-07-01) with the crucial detail: A Model 165 with one million bytes would rent for $98,715 a month and sell for $4,674,160. this allows us to calculate that, at the rental price and assuming 80% capacity utilization, each hour of effective computation cost 169 dollars lynn wheeler's memoirs https://www.garlic.com/~lynn/subtopic.html https://www.garlic.com/~lynn/subtopic.html are an irreplaceable source for information about this kind of thing; https://www.garlic.com/~lynn/2023b.html#0 https://www.garlic.com/~lynn/2023b.html#0 discusses the history of development of the 370 in https://narkive.com/9nl6cj2Q.3 https://narkive.com/9nl6cj2Q.3 (which is by wheeler but which i can't find in his own web pages) he says the model 168 was 3.0 mips, while the 370/195 (which i think never shipped) reached 10 mips peak http://www.beagle-ears.com/lars/engineer/comphist/model360.htm http://www.beagle-ears.com/lars/engineer/comphist/model360.h... says the 370 model 168 was 1.6 cycles per instruction, reaching 3.5 mips on the model 168-3, although 12.5÷1.6 = 7.8, not 3.5 (why am i not an ibm fan? consider this quote from chris date about why his seminal book on databases was delayed for 2 crucial years from https://archive.computerhistory.org/resources/access/text/2013/05/102658166-05-01-acc.pdf https://archive.computerhistory.org/resources/access/text/20... : > I wrote it very quickly, but I was in IBM. And for someone in IBM in those days to publish something, it had to go through the clearance procedures in IBM. And so I submitted it to the clearance procedure, and of course the problem with the book from an IBM point of view was that it was not coming out saying that IMS was the greatest product ever invented. So everybody who reviewed it in the clearance procedure did two things. First, they found something I had to change. And second, they found somebody else who had to review it. This process was clearly going to go on for a long time! (...) I did actually hawk a proposal and sample chapters around to several publishers, and I got some proposed contracts, but I wasn’t getting the clearance. )
- cardiffspaceman 2y ago
  As I look at the thoughtful comments, I think I omitted a detail that would help: the computer in question was a PDP-11 with interactive timesharing.

by User23 2y ago

cardiffspaceman 2y ago

In the USA, in the ‘70’s, I had an account on a university computer that was good for 4 hours in a month. I think that was just a fairly normal thing in the old days, when almost nobody had an Apple ][.

kragen 2y ago
also, i think it's a pretty large amount of computer time! it was enough to do things every month that would have required decades or centuries with a pocket calculator if you were using an ibm 370 model 168 http://www.bitsavers.org/pdf/ibm/370/funcChar/GA22-7010-4_370-168_funcChar_Jul76.pdf http://www.bitsavers.org/pdf/ibm/370/funcChar/GA22-7010-4_37..., you were running on a machine with 1 to 8 mebibytes of ram (dedicated entirely to your program if in batch mode), 16 mebibytes of virtual memory, an l1 cache which i think was 8 kibibytes by default, 1.3 megabytes per second of i/o per channel (with up to 12 channels), and a fixed-point (32-bit) multiply took 780 nanoseconds, so you could do about 1.3 million multiplies per second. your data would often be on magtape, which moved 2.9 meters per second, which would be 700 kilobytes per second at 6250 characters per inch (introduced 01973). 4 hours would be 18 billion multiplies the apple ][, by comparison, could have 64 kibibytes of ram, and read or write a floppy at about two kilobytes per second and run about 300'000 instructions per second, delivering 0.021 dhrystone mips on an apple //e, according to https://netlib.org/performance/html/dhrystone.data.col0.html https://netlib.org/performance/html/dhrystone.data.col0.html. so, coming at it from a batch processing perspective, this particular 370 model had about 64 times as much ram as a maxed-out apple ][, about 64 times as much computing power (maybe 1024× for floating-point stuff), and i/o on the order of 2048 times faster so those 4 hours of computer would allow you to process a quantity of data on magtape that would take about a year swapping floppies on an apple ][, or do an amount of calculation the apple would need weeks or months for suppose instead of the apple your alternative was an hp-35 non-programmable pocket calculator, introduced in 01972, or more or less equivalently, a slide rule. you need about 2 seconds to enter each new operand and press an operation key. we can derate those 18 billion multiplies in the 4-hour monthly allocation to about 5 billion total operations if we include cosines, square roots, etc. this would take you 300 years to do by hand on the hp-35. on a programmable hp-65 (introduced 01974) maybe only 30 years the enormous benefit of the apple ][ was that you got millisecond turnaround instead of hundred-kilosecond turnaround. for many purposes, those eight orders of magnitude less latency more than compensated for the two or three orders of magnitude you were sacrificing in throughput when i started using time-shared unix machines in the 01990s (according to the dhrystone link, the decstation 3100 was 13.4 dhrystone mips, so roughly 16 times the mainframe described above) i would log into a shell server with 16-64 other concurrent users. the default cpu time limit was, i think, 10 minutes. that is, when you launched a program, if it used 10 minutes of cpu, the os would kill it. before netscape, the only time i ever saw this happen was when i accidentally wrote infinite loops. i could use an interactive program like trn or tcsh or emacs for hours and hours without hitting that limit
- kragen 2y ago
  looking at the docs for the ibm 370 model 165 (https://bitsavers.org/pdf/ibm/370/systemGuide/GC20-1730-0_370-165_Guide_Nov70.pdf https://bitsavers.org/pdf/ibm/370/systemGuide/GC20-1730-0_37... from 01970, several years before the model 168 mentioned above) i came across these more detailed notes on cpu performance > The CPU has an 80-nanosecond cycle time and an 8-byte-wide data path. (...) Among the major elements in the CPU are the instruction unit, the execution unit, local storage, and control storage. > (...) The faster internal performance of the Model 165 is due in part to the use of more concurrence in CPU operations than is implemented in the Model 65. The Model 165 CPU contains an instruction unit and an execution unit that overlap instruction fetching and preparation with instruction execution. The Model 165 instruction unit is controlled by logic circuits and can process several instructions concurrently while the execution unit is executing a single instruction. The instruction unit prefetches instructions (maintaining them in sequence), decodes instructions, calculates addresses, prefetches instruction operands, and makes estimates of the success of conditional branches. When a conditional branch is encountered, the instructions immediately following the branch and those located at the branch address are prefetched and placed in separate instruction buffers within the instruction unit. Two 16-byte instruction buffers are used. This insures the availability of prefetched instructions whether the branch is taken or not. > The execution unit is microprogram controlled and can execute one instruction at a time. It has the capability of processing a new instruction every cycle. Emphasis is placed on optimizing fixed binary and floating-point arithmetic operations. A 64-bit parallel adder is used to perform binary and floating-point arithmetic, while an 8-bit serial adder is used in the execution of packed decimal arithmetic. processing a new instruction every 80-nanosecond cycle would be a peak performance of 12.5 mips, although presumably many instructions, in particular including multiplication, apparently took longer than that; i think the average was over 2 cycles per instruction. the 12.5 megahertz clock was the same on the model 168 i described above i'm not an ibm fan. but ibm mainframes might be the central example of 'the kind of large computer a person at a university in the 01970s might be allocated a few hours a month on' there's a wikipedia article about this particular model, mentioning it was discontinued in 01977: https://en.wikipedia.org/wiki/IBM_System/370_Model_165 https://en.wikipedia.org/wiki/IBM_System/370_Model_165 there's a table at the end of https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Papers/Padegs-IBM360-sep81.pdf https://www.ece.ucdavis.edu/~vojin/CLASSES/EEC272/S2005/Pape... describing the clock speed, cache size and associativity, cache line size, tlb size, etc., of numerous 360 and 370 models, including the 165 and 168, unfortunately lacking year of introduction. if someone else is doing this kind of investigation they may find it a useful reference ken shirriff has an overview of the 360 line at http://www.righto.com/2019/04/iconic-consoles-of-ibm-system360.html http://www.righto.com/2019/04/iconic-consoles-of-ibm-system3... nyt published an article on the introduction of the model 165 at https://www.nytimes.com/1970/07/01/archives/ibm-shows-2-new-computers-ibm-shows-2-new-computer-models.html https://www.nytimes.com/1970/07/01/archives/ibm-shows-2-new-... ('i.b.m. shows 2 new computers', gene smith, 01970-07-01) with the crucial detail: A Model 165 with one million bytes would rent for $98,715 a month and sell for $4,674,160. this allows us to calculate that, at the rental price and assuming 80% capacity utilization, each hour of effective computation cost 169 dollars lynn wheeler's memoirs https://www.garlic.com/~lynn/subtopic.html https://www.garlic.com/~lynn/subtopic.html are an irreplaceable source for information about this kind of thing; https://www.garlic.com/~lynn/2023b.html#0 https://www.garlic.com/~lynn/2023b.html#0 discusses the history of development of the 370 in https://narkive.com/9nl6cj2Q.3 https://narkive.com/9nl6cj2Q.3 (which is by wheeler but which i can't find in his own web pages) he says the model 168 was 3.0 mips, while the 370/195 (which i think never shipped) reached 10 mips peak http://www.beagle-ears.com/lars/engineer/comphist/model360.htm http://www.beagle-ears.com/lars/engineer/comphist/model360.h... says the 370 model 168 was 1.6 cycles per instruction, reaching 3.5 mips on the model 168-3, although 12.5÷1.6 = 7.8, not 3.5 (why am i not an ibm fan? consider this quote from chris date about why his seminal book on databases was delayed for 2 crucial years from https://archive.computerhistory.org/resources/access/text/2013/05/102658166-05-01-acc.pdf https://archive.computerhistory.org/resources/access/text/20... : > I wrote it very quickly, but I was in IBM. And for someone in IBM in those days to publish something, it had to go through the clearance procedures in IBM. And so I submitted it to the clearance procedure, and of course the problem with the book from an IBM point of view was that it was not coming out saying that IMS was the greatest product ever invented. So everybody who reviewed it in the clearance procedure did two things. First, they found something I had to change. And second, they found somebody else who had to review it. This process was clearly going to go on for a long time! (...) I did actually hawk a proposal and sample chapters around to several publishers, and I got some proposed contracts, but I wasn’t getting the clearance. )
cardiffspaceman 2y ago
As I look at the thoughtful comments, I think I omitted a detail that would help: the computer in question was a PDP-11 with interactive timesharing.