[HN Gopher] The Cray-1 Computer System (1977) [pdf]
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The Cray-1 Computer System (1977) [pdf]
Author : LordGrey
Score : 145 points
Date : 2026-01-09 19:05 UTC (4 days ago)
(HTM) web link (s3data.computerhistory.org)
(TXT) w3m dump (s3data.computerhistory.org)
| ggm wrote:
| to deploy a 2nd hand Cray-1 at UQ, we had to raise the ex-IBM
| 3033 floor, it turned out the bend radius for flourinert was NOT
| the same as a water cooled machine. We also installed a voltage
| re-generator which is basically a huge spinning mass, you convert
| Australian volts to DC, spin the machine, and take off re-
| generated high frequency volts for the cray, as well as 110v on
| the right hz for boring stuff alongside. the main bit ran off
| something like 400hz power, for some reason the CPU needed faster
| mains volts going in.
|
| The flourinert tank has a ball valve, like a toilet cistern. we
| hung a plastic lobster in ours, because we called the cray
| "Yabbie" (Queensland freshwater crayfish)
|
| That re-generator, the circuit breakers are .. touchy. the
| installation engineer nearly wet his trousers flipping on, the
| spark-bang was immense. Brown trouser moment.
|
| The front end access was Unisys X11 Unix terminals. They were
| built like a brick shithouse (to use the australianism) but were
| a nice machine. I did the acceptance testing, it included running
| up X11 and compiling and running the largest Conways game of life
| design I could find on the net. Seemed to run well.
|
| We got the machine as a tax-offset for a large Boeing purchase by
| Australian defence. End of life, one of the operators got the
| love-seat and turned it into a wardrobe in his bedroom.
|
| Another, more boring cray got installed at department of primary
| industries (Qld government) to do crops and weather modelling.
| The post cray-1 stuff was .. more ordinary. Circular compute unit
| was a moment in time.
|
| (I think I've posted most of this to HN before)
| bilegeek wrote:
| > the main bit ran off something like 400hz power, for some
| reason the CPU needed faster mains volts going in.
|
| Aerospace originally did that to reduce component size, CDC and
| IBM took advantage of the standard in the early 60's.
|
| Strangely, it seems mainframes didn't adopt switching power
| supplies until the end of the 70's, despite the tech being
| around since the end of the 60's.
| CamperBob2 wrote:
| 400 Hz is really the next best thing to a switching supply, as
| the transformers and filter capacitors can be smaller than they
| would need to be at 50/60 Hz. It can save cost and space for
| filter capacitors, especially in a three-phase system where
| there's not as much ripple to deal with.
|
| Another rationale may have been that the flywheel on the motor-
| generator would cover a multitude of power-quality sins.
| kev009 wrote:
| There a lot of discussion here
| https://retrocomputing.stackexchange.com/questions/7412/why-...
| but nothing seems conclusive.. I would wager the last answer,
| "IBM was using 400Hz", to be most directly causal reason. The
| motor-generator configuration might provide galvanic isolation
| and some immunity to spikes and transients as well?
| Animats wrote:
| Smaller transformers and capacitors in all the linear power
| supplies. 400Hz is still common in aircraft. Distribution
| losses are higher, but you're going across the room, not
| across the country.
| Polizeiposaune wrote:
| Cray-1 or Cray-2? IIRC Fluorinert was new with the Cray-2,
| while wikipedia suggests that the Cray-1 used a freon as
| coolant.
| ggm wrote:
| There you go. Not to doubt what you say, but we definitely
| had the love seat yet we also had a tank of vaguely
| flourescing green liquid. Maybe we had some intermediate
| state, the cray-1 cpu form but the cray-2 upgraded coolant.
|
| It wouldn't surprise me if we had the bastard love-child of
| leftovers from Boeing.
| maybewhenthesun wrote:
| You consistency in spelling fluor as flour gave me visions
| of using pancake batter as a coolant :-D
| xattt wrote:
| The GP also mentions X11 Terminals. My wiki-fu shows the X
| Windowing System came about on or around 1983, while Cray-1
| was 1970s vintage. I assume that was an upgrade at some later
| point.
| egberts1 wrote:
| X Window Release 3 (X11R3) was introduced on Cray into
| UNICOS (a UNIX variant of Cray OS, COS) in late 1989 using
| ported 64-bit Xlib. But it was not widely used within small
| Cray community.
|
| But MIT cooked up X11 "PROTOCOL" of Xlib in late 1985 to
| 1986 on Univac and Unix in C with many other X libraries
| written in Common Lisp.
|
| X10R3 mostly stabilized the Xlib around a few platforms and
| CPU architecture (DDX) in a"long" preparation for X11R1 in
| September 1987.
|
| https://www.x.org/wiki/X11R1/?utm_source=chatgpt.com
| bluGill wrote:
| Since this was a 2nd hand machine having the upgrades for
| X11 doesn't seem unlikely.
| ggm wrote:
| It was fat finger memory. it was X10R3 or something
| similar, which I had previously used in UCL on Ultrix
| machines in the 80s. I don't think it was R5, I don't think
| much got upgraded in that space but .. it was a long time
| ago.
|
| This was a SECOND HAND cray. It was a tax contra made in
| the 90s when Boeing sold a lot of stuff to the Australian
| Defence forces, and to avoid a massive tax burden donated
| science trash to the uni.
| pklausler wrote:
| Cray old-timer here; 'nert was definitely Cray-2 and later.
| In the Cray-3 it was turned into mist.
| markus_zhang wrote:
| Hello Bandit!
| FarmerPotato wrote:
| I used a Cray C-90 and T3D 256-core machine from 1995-1999. The
| T3D used commodity Alpha 21164, and was already behind the T3E
| when we got it (Cray refurbished.) By the end it was outclassed
| by an SGI Oxygen box with 8 CPUs. I'd already ported a lot of
| software from SunOS and HP-UX to Irix and Unicos (Cray) and it
| was easy to move it to Linux in the end.
| Grosvenor wrote:
| You means SGI onyx? The cool looking purple one?
| nyrikki wrote:
| IIRC the desk side onyx had the royal purple stripes and
| only accepted one CPU board, the rack mount version were
| that blue-purple color, more indigo (color)
| Grosvenor wrote:
| So there were two computers made with the same bits mid
| 90s. Origin(compute, blue) and onyx(graphics, purple).
| Both had deskside and rack systems.
|
| Onyx had a few slots reserved for graphics, original
| could have more compute boards. But you could certainly
| put two couple cpu boards in an onyx deskside or rack.
| nyrikki wrote:
| It must have been more complex then that, I was at the
| skywalker ranch when onyx was being replaced by o200/2000
| and never saw a purple onyx at Kerner(ILM), I had a
| purple Indy impact as my home machine and was looking for
| purple. I hated teal with a passion.
|
| Perhaps all the purple rack onyx had been dumped but we
| dug through ILMs boneyard looking to add to our cxfs
| cluster, but the FC bus speed was too low.
|
| It is possible that R10k was different or that there were
| multiple chassis. The desk sides I had experience with
| required RAM in slot 1, with CPU in slot 2, with up to 4
| CPUs on the board.
|
| o200 was more restrictive, with 2 CPUs per chassis, with
| the ability to cray-link two chassis for a total of 4
| CPUs, more required o2000.
|
| But this was a quarter of a century ago or more by
| now...so I may misremember things.
| Grosvenor wrote:
| Oh I think you may be right here. I was thinking
| originally 2000/onyx 2 which were basically the same
| system just with or without graphics pipes.
|
| And you're right origin had three models (maybe more) a
| tower system (o200), a deskside system (same as onyx2)
| and a rack (same as onyx2).
|
| For Indy impact so you mean the teal/purple indigo2?
| Weirdly the teal desktop was named indigo2..
|
| Weird but cool stuff.
| nyrikki wrote:
| I actually forgot that they made a low end 'Indy' and
| never saw one. We called the Indigo2 Indy
|
| There were some oddities with ad dollars and prestige
| clients in the 90s, where systems would be upgraded,
| avoiding swapping out the serialized, asset tagged parts,
| yet upgrading systems.
|
| The teal Indigo2s were the original with the impact
| graphics ones being purple.
|
| But all the Indigo2s I saw typically were r10k + max
| impact graphics despite the color.
|
| The cases were identical.
|
| But Evans & Sutherland and Lucas are the only places I
| dealt with SGI, so probably not a good source for typical
| customer's experience
| Grosvenor wrote:
| I'm tugging at my memory with this page:
| http://www.sgistuff.net/hardware/systems/index.html
|
| I had a teal Indigo2, an O2, and an Indy at various
| points. Neat stuff, but time moves on.
|
| There's some complex setups listed in the origin/onyx
| pages. You could mostly mix and match boards to get what
| you wanted.
| nyrikki wrote:
| I should add, the o200 was a 4u chassis with a desk side
| skin option.
|
| If you popped off the plastic and had rails you could
| convert them.
|
| The o200 had stonith (shoot the other node in the head)
| ports like the o2000 for clustering etc..
| FarmerPotato wrote:
| Uhoh, I think I mistook Oxygen for Origin. It was 25
| years ago.
|
| The funny thing was that our Cray sales team, from the
| C90 and T3D, jumped ship from Cray to SGI before their
| merger.
|
| So got to set up some Indys as web servers/ Oracle
| database. Surprise! Same sales team. Then the merger
| happened and we got the Origin boxes.
| twoodfin wrote:
| The CRAY-1 was so ridiculously ahead of its time that it took
| until the Pentium MMX (1997) for "ordinary" computers to catch up
| to its raw performance.
|
| That's 20 years or about 10,000X the available VLSI transistors
| via Moore's Law.
| fnord77 wrote:
| Not terribly impressive considering an average 20 year old
| super computer c. 2005 is still about 100x as fast as today's
| best consumer cpus
| twoodfin wrote:
| Well, yeah, Dennard scaling ended around 20 years ago!
| firecall wrote:
| I wonder how many times faster my iPhone 17 Pro Max is?
|
| Sometimes I like to remind myself we are living in the future.
| A future that seemed like SciFi when I was a kid in the 70s!
|
| Sadly I don't think we will ever see Warp Drives, Time Travel
| or World Peace. But we might get Jet Packs!
| FridayoLeary wrote:
| At the risk of sounding cliche i'll point out that ios
| probably uses several times the capacity of a cray 1 just to
| get the keyboard to work.
| estimator7292 wrote:
| Yes, but the impressive part is that the iPhone does it on
| a few mW instead of a few MW
| hypersoar wrote:
| From the Wikipedia article on the Cray 1:
|
| "The 160 MFLOPS Cray-1 was succeeded in 1982 by the 800
| MFLOPS Cray X-MP, the first Cray multi-processing computer.
| In 1985, the very advanced Cray-2, capable of 1.9 GFLOPS peak
| performance
|
| ...
|
| By comparison, the processor in a typical 2013 smart device,
| such as a Google Nexus 10 or HTC One, performs at roughly 1
| GFLOPS,[6] while the A13 processor in a 2019 iPhone 11
| performs at 154.9 GFLOPS,[7] a mark supercomputers succeeding
| the Cray-1 would not reach until 1994."
| hulitu wrote:
| > while the A13 processor in a 2019 iPhone 11 performs at
| 154.9 GFLOPS,[
|
| Sustained ? Or just for some ms when the thermals kick in ?
| wmoxam wrote:
| Recently I've found myself wanting a tricorder type device.
| esseph wrote:
| With the visual analysis of LLMs, throw in some extra
| ingredients with a camera, microphone, speaker, and
| display, and were getting close. Add Bluetooth for
| biosensors and... Iterate a couple of generations...
|
| We're getting there!
| qsera wrote:
| >how many times faster my iPhone 17 Pro Max is..
|
| Sadly most of that power is not working for you, most of the
| time, but working against you, by spying, tracking and
| manipulating you.
|
| Bet that was not include in your sci-fi dreams in 70s..
| FarmerPotato wrote:
| Oh but we had The Forbin Project, its sequel Colossus, and
| later Wargames. Not to mention Star Trek episodes with
| malignant computers. And I have No Mouth But I Must Scream.
|
| In the 70s, science fiction fed me Cold War fears of world-
| controlling mainframes.
| drfuchs wrote:
| Colossus: The Forbin Project is simply a renamed release
| of The Forbin Project, a few months after the later had a
| poor opening. Didn't help the box office much. I liked
| it, back when it was easy to dismiss as an impossible
| dystopia.
| FarmerPotato wrote:
| Oh. Well the sequel in print was named Colossus. It is
| about continuing life under the reign of supercomputer.
| Angostura wrote:
| I'd love to see you substantiate that - bet you can't.
| timbit42 wrote:
| I certainly can't. I'm running GrapheneOS.
| chasil wrote:
| Seymour Cray never designed a silicon microprocessor. I wonder
| what he would have created had that opportunity presented
| itself.
|
| https://en.wikipedia.org/wiki/Seymour_Cray
| __patchbit__ wrote:
| In his memory some have said his name are the last two
| characters in RISC and CISC.
| antonvs wrote:
| > The CRAY-1 was so ridiculously ahead of its time that it took
| until the Pentium MMX ...
|
| You'd need a different comparison to show how the Cray-1 was
| special. If the comparison is to single commodity CPUs, like
| the Pentium MMX, you could make much the same comparison for
| many mainframes and supercomputers. Several supercomputers in
| the 1980s exceeded 1 GFLOP, for example, and it wasn't until
| the 2000s that you could get commodity CPUs with that
| performance.
| effnorwood wrote:
| Blew my mind age 4. Then found out about the imos transputer. And
| robotics magazine. 70's were popping. Ponging?
| SirIsaacGluten wrote:
| Inmos not imos, if my memory cells serve ne correctly. I lived
| overseas at the time, so I did not hear about the Cray till
| like 1980/81. My friend (we were like 12) had an idea to write
| a simulator for digital circuits, and I was puzzled as to why
| you would want to simulate a circuit when you can build it and
| test it. He was way ahead of his time.
| lukeh wrote:
| XMOS is still keeping the Inmos dream alive, more or less!
| HarHarVeryFunny wrote:
| The Transputer was ahead of it's time, maybe due to
| anticipating the end of Moore's law a bit too early!
|
| The Transputer's inter-chip channel connections remind a bit of
| Nvidia's NVLink or AMD's Infinity Fabric.
| october8140 wrote:
| > The aesthetics of the machine have not been neglected. The CPU
| is attractively housed in a cylindrical cabinet. The chassis are
| arranged two per each of the twelve wedge-shaped columns. At the
| base are the twelve power supplies. The power supply cabinets,
| which extend outward from the base are vinyl padded to provide
| seating for computer personnel.
| postexitus wrote:
| It looks really nice - but never understood the seating. Who
| came up with that?
| wongarsu wrote:
| It ensures the Cray is placed as the centerpiece of the room,
| not as mere equipment shoved on the wall
| postexitus wrote:
| Probably they could achieve the same with circular
| construction but without the seats.
| t1234s wrote:
| Answers my question.. I always thought they can't possibly want
| people sitting on something so expensive.
| tvguide61 wrote:
| Why the thin black curtain on the window?
|
| Thoughts:
|
| 1. To block some sunlight from getting in.
|
| 2. It's a secure facility and wanted to prevent people from
| looking in.
|
| 3. To not have to look at something outside.
|
| 4. It's a secure facility and wanted to prevent the chance of
| taking a picture of someone or something outside that could
| compromise the location of the computer or someone's identity;
| sometimes the first place a photogenic computer was built was at
| a customer site.
| ssl-3 wrote:
| Or, you know: Sometimes, a window shade is just a window shade.
| estimator7292 wrote:
| It was the 70s, and that was simply the style at the time.
| fredoralive wrote:
| I suspect the curtains are closed to avoid causing exposure
| issues etc. in the photos being taken.
|
| As for windows in a computer room, seems a bit unusual, but a
| nicer working environment than the usual windowless box I'd
| guess...
| bluGill wrote:
| Many computer rooms had windows. Computers were expensive
| things that companies often wanted to show off - but they
| needed special rooms with raised floors, HVAC (which also
| make them look even more exclusive/impressive and worth
| showing off), and the cost (millions of dollars when senior
| operators might be making $50k/year) meant you wanted to be
| careful who could touch them. Thus a window so that you could
| bring outsiders by the room on the way to a meeting and they
| could look in and see that shiny equipment.
|
| Remember in 1980 the modern PC wasn't even invented (Apple II
| was) yes. Most people didn't have access to any terminal as
| part of their job, only specialized positions did.
| Typewriters where was everyone had on their desk. As such a
| computer was something a company could wow visitors with.
| Times have changed.
| DonHopkins wrote:
| I had the cover of this pinned up on my wall! Supercomputer porn.
| DonHopkins wrote:
| I knew a guy who worked at one of the national labs that had its
| own Cray supercomputer, in a computer room with a big observation
| window that visitors could admire it through, of course (all
| Crays required observations windows to show them off).
|
| Just before a tour group came by, he hid inside the Cray, and
| waited for them to arrive. Then he casually strolled out from the
| back of the Cray, pulling up the zipper of his jeans, with a
| sheepish relieved expression on his face, looked up and saw the
| tour group, acted startled, then scurried away.
| technofiend wrote:
| The Cray 1-ish machines I had access to at Shell and Chevron
| were most definitely tucked away in rooms with no visibility
| into them. In fact the Chevron machine room had pretty stern
| "no photography" placards, which I took seriously and is sadly
| why I don't have a photo of sitting on the loveseat of their
| machine.
|
| Getting access took just short an act of God and I was a
| sysadmin in the central support group! They didn't want us
| puttering on the machines, so as far as I could tell it mostly
| sat idle.
| MonkeyClub wrote:
| > a photo of sitting on the loveseat of their machine.
|
| Unsurprisingly, I would say, the Cray is literally the prime
| example in "A Gallery of Computers as Furniture".[+]
|
| [+] https://news.ycombinator.com/item?id=46601097
| NL807 wrote:
| Documentation is fantastic.
| awacs wrote:
| I remember doing a report on this in high school in the late 80s.
| I'd love to do an order of magnitude comparison to a modern M4
| Mac... Amazing how far we've come.
| hulitu wrote:
| > I'd love to do an order of magnitude comparison to a modern
| M4 Mac... Amazing how far we've come.
|
| Yes, would be nice to compare the capabilities (multiuser,
| multitasking, security, RCE). Did we get _so_ far ? How many
| users can a Mac sustain ?
| TheOtherHobbes wrote:
| Cray 1 - 160 MFLOPS
|
| M4 CPU - 280 GFLOPS
|
| M4 GPU - 2900 GFLOPS
| fghorow wrote:
| I just did a BOTE calculation for my iPhone (A17 Pro chip; GPU
| rated at 4 Tflops). According to the sales blurbage in TFA, the
| Cray 1 performed at 80 Mflops. (Yes, that is OBVIOUSLY not
| comparing apples to Apples -- pun intended). Unless I've
| dropped a decimal point, my iPhone is (capable of) 50,000 times
| the floating point speed of a Cray 1.
|
| In my back pocket. To watch cat videos.
| AnimalMuppet wrote:
| I remember computer magazines of the time talking about "a Cray
| on a chip" in their April 1st jokes.
|
| Well... we're there. Far past, in fact. We live in the future
| that then was so far out of reach that people could only joke
| about it, not consider it a realistic possibility.
|
| In one lifetime.
| 5- wrote:
| for a much more in-depth description of its predecessor, see
| https://archive.computerhistory.org/resources/text/CDC/cdc.6...
|
| i don't think there is a comparable book about the cray-1?
| bytesandbits wrote:
| who was the industrial designer? Cray-1 fits so well it looks
| straight out of 2001: A space Odyssey
| idatum wrote:
| In the past few years whenever I re-watch 2001 when Dave is
| shutting down HAL, I see a spaceship capable data center. And
| HAL sings "Daisy.." finally at the foundational, bare metal
| layer.
| themafia wrote:
| Cray himself. Here's a talk about designing it. My favorite
| part is his description of the aluminum machining they had to
| invent in order to move the freon through the frame to keep the
| machine from melting. It's a great talk.
|
| https://www.youtube.com/watch?v=vtOA1vuoDgQ
| ckastner wrote:
| somewhat related:
|
| _" Seymour said he thought it was odd that Apple bought a Cray
| to design Macs because he was using Macs to design Crays. He
| sent me his designs for the Cray 3 in MacDraw on a floppy."
| reports KentK._
|
| https://cray-history.net/2021/07/16/apple-computer-and-cray-...
| zippyman55 wrote:
| My first time on Cray, I thought I had a core dump, my program
| ended so quickly. No, the job had finished.
| jeffrallen wrote:
| Same with "go test". :)
| qingcharles wrote:
| Am I right in thinking there are no working Cray-1s?
|
| I know a couple of museums have them, but I don't think any
| software has ever surfaced, am I right?
| pinewurst wrote:
| No, both COS (but missing Cray Fortran) and Unicos have been
| located.
| feurio wrote:
| > "The compact mainframe occupies a _MERE_ 70 sq. ft. of floor
| space. "
|
| (emphasis mine)
| tvali wrote:
| Compare this to modern system: we could fully simulate this kind
| of slow computer in real time, I would guess, with all the
| wheels, clockwork and mechanics as well as logic circuits with
| full electricity. Deciding the simulation level would be a bit
| challenging - is this an atomic, an electron or more common sense
| simulation -; still I think the simulation would work as well as
| this kind of document.
| formerly_proven wrote:
| Absolutely not on the electrical level. ISA emulation,
| probably, maybe, though these Crays are not IEEE machines so
| you have to actually fully emulate the floating point
| operations, instead of punting them to the FPU. That may make
| getting hundreds of MFLOPs on difficult.
| W-Stool wrote:
| If these kinds of machines interest you I highly recommend the
| book "The Supermen" by Charles Murray. It has all the details you
| would ever want on Seymour Cray and others in the business.
|
| I was working at a geophysical company in the 80's and we lusted
| after a Cray-1. Best we could afford where array processors
| (CSPI) connected to VAX systems.
| LgWoodenBadger wrote:
| In college I had an account on our ACM chapter's DEC Alpha, which
| I used primarily for mudding. Its DNS name was cray-
| ymp.xxx.xxx.edu, which resulted in more than a few moments of
| shock/consternation from mods. "You're mudding from a CRAY
| Y-MP???"
| TZubiri wrote:
| Before IBM's deep blue, apparently there was a chess program
| called Cray Blitz, I'm sure the cray had the raw power(20MHz? But
| with 64 parallel operations) needed to beat the top humans, but
| the software just wasn't there yet.
|
| Blitz was ported to C and continued development FOSS as Crafty,
| mainly by a U of Alabama professor, but to this day it can't beat
| top humans on modern cpu (topping at 2650 elo instead of 2850 of,
| say, carlsen.)
| lebuffon wrote:
| I quickly skimmed the instruction set and did not see anything
| resembling a sub-routine call or branch and link instruction.
|
| Did I miss it?
| HarHarVeryFunny wrote:
| The "R exp" is subroutine call (which saves return address to
| register B00), and I believe "J Bjk" is the subroutine return.
|
| The Cray-1 didn't have a hardware stack, so subroutine call is
| basically just jump there and back, using a register for the
| return address rather than pushing/popping it to/from the
| stack.
|
| Another oddity of the instruction set that stands out (since
| I'm in process of defining a VM ISA for a hobby project) is
| that the branch instructions test a register (A0 or S0) rather
| than look at status flags. In a modern CPU a conditional
| branch, if (x < y), is implemented by compare then branch where
| the compare instruction sets flags as if it had done a
| subtraction, but doesn't actually modify the accumulator. In
| the Cray this is evidentially done by doing an actual
| subtraction, leaving the result in A0, then branching by
| looking at the value of A0 (vs looking at flags set by CMP).
|
| Gemini explains this as being to help pipelining.
| commandlinefan wrote:
| I recall when reading TAOCP that Knuth's MIX assembly
| supported subroutines by requiring the caller to modify the
| RET call to it's own address (obviously not re-entrant!).
| This sort of thing was common when Knuth started in the early
| 60's, may have still been around by the time of the Cray.
| HarHarVeryFunny wrote:
| This Cray version isn't so bad - it just requires that if
| the callee itself calls other subroutines, then it has to
| save/restore this B00 return address register. You could
| still support re-entrant routines with this as long as you
| saved/restored the return address to a software stack
| rather than a fixed location, but I wonder if Cray
| compilers typically supported that?
|
| Apparently the reason for using a register vs stack for
| return address was because memory access (stack) was so
| much slower.
|
| I'm kinda tempted to use this for the VM I'm designing,
| which will run on the 6502 8-bit micro. The 6502 doesn't
| have any 16-bit operations, so pushing and popping using a
| software defined 16-bit stack pointer is slow, and saving
| return address to zero page would certainly be faster. It'd
| mean that rather than always pushing/popping the SP, you
| only do it in the callee if needed. It's an interesting
| idea!
| antonvs wrote:
| Subroutine calls are for the weak :)
|
| There's some more detail here: https://ed-thelen.org/comp-
| hist/CRAY-1-HardRefMan/CRAY-1-HRM...
|
| The following quote gives some sense of how "manual" this was:
|
| > "On execution of the return jump instruction (007), register
| Boo is set to the next instruction parcel address (P) and a
| branch to an address specified by ijkm occurs. Upon receiving
| control, the called routine will conventionally save (Boo) so
| that the Boo register will be free for the called routine to
| initiate return jumps of its own. When a called routine wishes
| to return to its caller, it restores the saved address and
| executes a 005 instruction. This instruction, which is a branch
| to (Bjk), causes the address saved in Bjk to be entered into P
| as the address of the next instruction parcel to be executed."
|
| Details were up to the compiler that produced the machine code.
| FarmerPotato wrote:
| Essentially, the B00 register is a Top Of (Return) Stack or
| TOS register. It's great for leaf routines.
|
| You have to push it to your preferred stack before the next
| operation. You do the cycle-counting to decide if it's a good
| ISA for your implementation, or not.
|
| Obviously, ISAs with a JSR that pushes to stack are always
| using an extra ALU cycle for the SP math, then a memory
| write.
|
| Doing it with a (maybe costless) register transfer followed
| by (only sometimes) a stack PUSH can work out to the same
| number of cycles.
|
| With improvements in memory speed or CPU speed, that decision
| can flip.
|
| Consider that in this era, your ALU also had the job of
| incrementing the PC during an idle pipeline stage (maybe the
| instruction decode). Doing a SP increment for a PUSH might
| compete with that, so separating the two might make the
| pipeline more uniform. I don't know any of the Cray ISAs so
| this is just a guess.
| csmoak wrote:
| whenever i hear about a Cray, i'm always reminded of the scene in
| the movie Sneakers where they sit on one to have a conversation
| dongecko wrote:
| I never realized; thanks for pointing that out. Sneakers is one
| of my favorite movies.
| AKluge wrote:
| I was a heavy user of the Cray-1, Cray-XMP and Cray-2 at the
| magnetic fusion computing center at Lawrence Livermore National
| Lab. One of the important things to remember was that the Crays
| of this generation were vector processors, that is they carried
| out operations across multiple elements of arrays at once. If you
| didn't structure your code properly, you didn't see these
| extraordinarily high instruction rates.
|
| And, yes, quite some time ago I noticed that my cell phone had
| surpassed the capabilities of these early Crays :)
| commandlinefan wrote:
| According to this link
| https://www.datacenterdynamics.com/en/news/cray-1-supercompu...
| these things retailed for $8 million (in 1975 dollars!). That's
| almost $50,000,000 today - I can't even imagine how much work
| went into justifying a purchase like that.
| jgalt212 wrote:
| How does a vector processor of yore compare to SIMD of the late
| 90s to the current day? Are they two words for the same thing?
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