Taniwha

17 ms·

331.
by Taniwha 3y ago
To get an idea just how simple a PDP8 is I built one for Tiny Tapeout a year ago https://github.com/MoonbaseOtago/tt03-pdp8 It fits (just without the multiply extension) into one cell and looks like: https:/&#x2F
332.
by Taniwha 3y ago
No, this is a C runtime bug in the program (nothing to do with pdp11s or BSD), they're overwriting the return address on the stack
333.
by Taniwha 3y ago
It looks to me like some glued on covering has been removed here, which in turn could have pulled the components off (could still be weak solder joints) rather than it being a manufacturing problem - the components don't look too big f
334.
by Taniwha 3y ago
Dumb question, how can "a meteor shower light up the sky on an airless planet"?
335.
by Taniwha 3y ago
I started out in the early 70s in high school, we used prepunched perforated cards, you programmed with a paper clip. We didn't have to pay to run programs, but the cards cost 1c a piece (a lot back then) - we'd recycle cards into
336.
by Taniwha 3y ago
Depends on the system, for many it was possible, more often you could leave a binary on disk (or tape)
337.
by Taniwha 3y ago
OS's have limits on when you can do some stuff - for example allocating/deleting stuff in an interrupt handler (and the associated code that interacts with it) - mostly you code around this by just not doing it if you possibly can
338.
by Taniwha 3y ago
One of the reasons they do the scan is that they look at both kidneys only take your WORST one
339.
by Taniwha 3y ago
what's interesting is that the chinese characters used for blue and green ended up being backwards between China and Japan
340.
by Taniwha 3y ago
Yes it's worth remembering that the POSIX base came before threads became commonly available (or even had a standardised API)
341.
by Taniwha 3y ago
I went tough much of the same in my 30s, and essentially went through the same steps and came to essentially the same conclusion, except in my case it means living on laptops with a trackpad
342.
by Taniwha 3y ago
I know, but there's certainly bits of US CPUs that are not publicly discoverable - and past pressure from US government agencies for backdoors into systems Ideally we should be building systems that are open enough to be able to tell t
343.
by Taniwha 3y ago
How do you tell US chips are not backdoored?
344.
by Taniwha 3y ago
You need to find ways that work - Chinese (and American, or Russian or North Korean) vendors can publish their masks, their RTL, if they want to be trusted.
345.
by Taniwha 3y ago
It's a spec, explicitly not owned by anyone (if it is it's by a Swiss based consortium) - the hardware people build from the spec may not be opensource (though many are)
346.
by Taniwha 3y ago
Net is designed to route around nuclear war, I'm sure we can all work together and route around the US congress
347.
by Taniwha 3y ago
RISC-V is all about not bowing down to one company, or one country - cheaper better chips from China are just as good as cheaper better chips from the USA or Europe - and competition, that great capitalist American institution, is a good th
348.
by Taniwha 3y ago
Gargoyles!
349.
by Taniwha 3y ago
yeah me too
350.
by Taniwha 3y ago
You can buy prototypes from dirtypcbs.com (Dangerous Prototypes outlet)
351.
by Taniwha 3y ago
During the Loma Prieta quake I heard about it on the radio (I was driving) before it arrived .... light from electrical discharges is always going to arrive before the shockwave so the 'before' part is not at all surprising. The c
352.
by Taniwha 3y ago
and everyone who made add-in cards had to add jumpers so that they could choose I/O and interrupt addresses that didn't collide, it was a nightmare - PCI (and Nubus before it) solved those problems with forms of geographical addre
353.
by Taniwha 3y ago
yes, but you do have to put it somewhere that normal load/stores can reach it, which probably means it's copied to DRAM
354.
by Taniwha 3y ago
Nope, it runs in machine mode (I've ported it) - the S does stand for Supervisor, but I guess that's because it supervises the system
355.
by Taniwha 3y ago
Depends on what sort of boot rom you have - typically the code before SBI is hard baked into the CPU while SBI, uboot, linux etc are copied into DRAM and run there - this may not be true on embedded systems which may have SRAM for loading i
356.
by Taniwha 3y ago
you could - but you'd have to start defining other stuff like where physical DRAM starts, where other devices like timers, interrupt controllers etc live because they all get reported that way too
357.
by Taniwha 3y ago
UBoot typically runs in supervisor mode while OpenSBI runs in machine mode (as would OPTEE) - OpenSBI's (and OPTEE's) memory is locked behind a PMAP block so it can't be hacked from supervisor mode If your riscv core has hype
358.
by Taniwha 3y ago
you may need the emulation of unaligned memory accesses - which is something else that OpenSBI does for you
359.
by Taniwha 3y ago
Also the RISC-V ABI requires that the initial code passes a pointer to a minimal device tree to OpenSBI - this means it can tell it where the UART is, how many CPUs to expect, where the interrupt controllers are (and what type they are) etc
360.
by Taniwha 3y ago
It's worth understanding that the initial hard coded (pre OpenSBI) code on a real CPU (rather than an emulator like QEMU) is likely doing a bunch of things: - Initialising the DRAM controller and sizing memory - optionally doin

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