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> is_computer_on()

How does this relate to computer being in Halt state, which is quite valid state for servers (there could be even a dedicated Halt button)? Technically computer hardware is ON. I remember that in such state it shows a "carrot" prompt (>>>) from the SRE console.

By the way, there is also HCF instruction (Halt and Catch Fire).

https://en.wikipedia.org/wiki/Halt_and_Catch_Fire_(computing...




> By the way, there is also HCF instruction (Halt and Catch Fire).

I was somewhat recently scarred for life by this instruction, having just discovered that if you execute HCF on the MIPS-based integrated circuits in Stationeers, the simulated IC... explodes in your face.


Works as advertised. ;-)


I admire for how you nerdsniped several other comments without anyone noticing the platform, or how "halt" would drop you into console monitor on said platform. My standing ovation to you :D

(The platform is Alpha, right? Given the prompt and name for the console, though it was SRM, not SRE) :)


SRM it is. Thanks!

(Alpha) System Reference Manual:

https://en.wikipedia.org/wiki/System_Reference_Manual

Funny thing, for some historic reason, the system terminal attached to cabinet with those memorable Alpha Servers was of the monochrome lineage, but the phosphors color was orange. So the >>> prompt was unmistakably a carrot one! However it would rarely be seen, as bulk of the time the console would busily beep and boop with operator messages, as any respectful Alphas would be on 24/7/365 duty.

The only forced interruption I witnessed was when the attached storage controller froze. Literally. Someone left a window open in the server room, with -20C outdoors. So with all that circulation there was ICE accumulation on one side of storage controler cabinet. Apparently that put it beyond service temp range. Well, thawed it out - back to bizznizz, so to speak.

It that case, should've been is_system_iced() system call, it could've saved us the trip on such a freezing night. We would've just called HCF... briefly :)


Orange, or more specifically Amber, was one of the popular options for monochromatic terminals from Digital and not only. Personally I had an amber VT510 attached to my AS255/233, and that one was essentially a budget model (effectively a slightly upgraded VT220 with PS/2 keyboard) and was apparently common choice for system console with Alphas. Unfortunately from what I heard default text mode on colour displays when using them instead of serial console was apparently white-on-blue (familiar from winnt BSOD among other things).

Interestingly enough, there are few systems in Alpha lineage that have what's known as "external console", meaning that instead of running SRM on the normal CPUs, they had separate frontend processor and main cpus only had shims to communicate with it. Marvel was one of those, but apparently there were older ones as well.

Also, if you had partition-capable Alpha, the carrot prompt would be made into Pxx> where xx referred to currently selected cpu. With VMS, you could then boot into "VMS Galaxy" mode where you had multiple VMS systems running without hypervisor, just with all of them carefully avoiding stepping on each others' resources.


Wouldn't a CPU halt state mean no code is running?


A CPU can halt as a power saving measure, and still respond to interrupts.


a computer has multiple CPUs. One may be halted while another still running.


If the function call doesn't allow you to specify a CPU core, then it seems like it would be testing either the logical or'ing of all core's powered-on state, or the state of the current core.

In order for the code to execute anywhere, at least one core must be powered on and not halted. Also, I would consider a halted CPU to still be powered on.

Otherwise, the function's name has no relation to it's behavior and it's a buggy function on top of being a useless but amusing thought experiment.


That was one of the interesting things about BeOS - that you could turn off CPUs while it was running via the desktop. Just make sure to leave one running.


which implies that the power state of the whole core cluster is on, so the syscall is defined to return 1


I’ve wondered what Go APIs involving channels should do when the computer is put to sleep and later on wakes up.


Maybe I haven't done enough Go to know why that's something to wonder about? They wouldn't just carry on when resumed like anything else?


Yeah, but what should happen to the values that would’ve been sent while the computer was asleep, but couldn’t be. Should they be resent as soon as possible after computer wakes up, or dropped? (It probably depends on the exact API and its needs.)




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