this post was submitted on 12 Nov 2023
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What do you mean by "almost no safety"?
Edit: OP edited his comment to clarify. He only had "parallel" without the "no multi-thread/multi-core" bit.
A CPU is a very complex gate array which handles bothersome tasks such as synchronization (run conditions) and memory access, and presents you with a very limited set of instructions. All serial programming builds upon this very limited set of instructions, and the instructions have been thoroughly tested over the past 6 decades.
Not to say that CPU architecture or microcode is fail-safe, but the chance of your computer blue-screening because of a failure of your CPU is rather small.
Now, parallel programming (the low level variant, not the hijacked definition) is the art of "wiring" those gate arrays. A CPU is actually made using parallel programming, so all the safeties it presents for serial programming will not be present in parallel programming, as parallel programming does not use a CPU.
EDIT: the above is of course simplified, there exist multiple architectures, collected into more common instructions sets such as amd64, armhf, arm64, etc. but even the most barebone processing unit contains a lot of securities and nicities that parallel does not have.
You lost me at parallel programming not using a CPU.
Perhaps you mean that it uses the lower levels of the CPU.
But regardless, I see that you mean that parallel programming involves almost no safety at the hardware level. Which is a weird thing to say since "serial programming" at the assembly level also offers no safety (e.g. if your program runs at ring 0.)
I think you are misunderstanding me. Are you perhaps thinking about multithreading or multi core? Because some people have also started calling that "parallel", even if it is nothing like low-level parallel.
A CPU does not build upon a CPU, a CPU builds upon transistors which are collected into gates, and which can be assembled into the correct order using parallel programming.
EDIT: as an example, you do not actually need a computer to parallel program. Get yourself a box of transistor, some cable, and a soldering iron, and you can build some very rudimentary gate arrays, like a flip-flop.
This link might give a better understanding of our confusion.
EDIT 2: One could perhaps illustrate the confusion which this topic is often victim of as such:
Transistors are part of the hardware and are parallel programmed to form complex gate arrays called "Processors", which feature instruction sets used by machine code, which is made using assembly, which is called "serial programming", which enables high-complexity operations such as multi-core "parallel" programming.
I'm talking about the former "PGA parallel programming", and not the latter "multi-core parallel programming".
I understand all that. I wrote my first 6502 assembler program in 1989 - and it was fun, by the way!
I am also aware that today's CPUs are nothing like the 8-bit CPUs of the 80s. So we're on the same page in that respect.
I understand what you're saying now. You're talking about programmable gate arrays, which is cool. But I still don't understand how "parallel programming" gate arrays comes with almost no safety compared to "serial programming" gate arrays. If you are not careful in either mode, you can introduce serious bugs in the programming.
Right, apologies for dumping it down so far, I find it hard to properly gauge the knowledge of others on the internet, and just try and play safe.
I wasn't aware that one could serial program gate arrays, as, as far as I know, the definition of serial programming is code that is governed by a processor, and which prohibits anything but serial execution of commands. So it's new to me that gate arrays can run serial code without any governance or serialization process, since gate arrays by themselves are anything but serial. Or rather, you need to synchronize anything and everything that is supposed to be serial by yourself, or use pre-built and pre-synced blocks, I guess.
Anyway, going by the definition that serial programming can only be performed using some kind of governance or synchronizing authority, that alone would be another layer of security.
As serial implies, it rid us, or lessened the burden, of those timing related issues, some of which included:
And the list goes on, but you know.
Serial also has a lot of pitfalls, and you can definitely screw things up bad, but at least you don't have to think much about clock or timing, or memory placement, unless communicating between devices or cores, and those sync problems tend to be rather tame and simple compared to intra-processor problems.
At least from my experience.
Oh if serial programming is not a thing in the electronics low level realm, then all is well. It's not news. It just doesn't exist. Apologies. I just assumed it was a thing since you said "parallel programming comes with almost no safety," and in my eyes, that implied that there existed other kinds of programming besides parallel in the context you were referring to.