- entry 2022/11/11

What a twat!

Driving to work on Saturday morning, I noticed bins all around. Were they on strike? I hadn't read anything about that in the paper. The French, more or less, were not on strike (fuel worker protests aside) which is unheard of - this is France, somebody somewhere has to be waving a big CGT flag on any given Thursday.
Instead, Britain is on strike. That's unheard of. It's almost like the seventies.

Then I remembered. Tuesday was a public holiday, so the collections are all a day late.

Somehow, a facepalm emoji doesn't quite suffice does it?

Pasta and potatoes

Lidl Halloween pasta.

Since there was about 300g of dried pasta, that cooked up to be around a kilogram of edible pasta. Tossed in butter and lightly peppered. Lovely!

There were four shapes - spider, bat, pumpkin, and ghost. There were three colours of pasta. Normal yellow, a red (from tomato), and a sort of brownish (from black carrot).

Lidl Halloween pasta, shapes and colours.

Last night while having a bath and passing my clothes through the washing machine, I had the halogen cooker on to bake two potatoes. Buttered, covered in grated cheddar…
...and it was unimpressive. The potatoes were mushy. Not bad, they just weren't a firm type. Being the type "Blanche" and sold as good for the oven, it's a shame as they were pleasingly large.

Cheesy spuds.

I decided to have some fun with the macro lens.

Yellow mush wrapped in old leather?

Gaping chasm. The air hole?

And since this final one looks like an oddly rendered landscape, it's only right that I paste in the little spacecraft from Zarch.

Shoot the...aliens?

Lidl

Anyway, walked around. Got some chicken burger things, that weird not-yoghurt, and some croissants. Then I discovered the in-store baker also makes cookies. Proper soft-in-the-middle bendy cookies, not those awful burnt offerings that seem so common around here.

Proper fresh cookies!

Warrior Nun

RISC OS 64

This is, of course, quite impossible. Our future, to keep RISC OS more or less as it is, lies in a 32 bit emulation.

Why? Well two reasons. The first is that huge swathes of the OS are written in assembler. There wasn't much in the change between ARM26 of the old original days and ARM32 we use now. It was mostly around splitting the combined PC (current execution location) and PSR (status flags) into separate registers. This was necessary as the combined method only provided 26 bits for the execution address (hence why it is known as ARM26 even though it's a 32 bit processor) which means it can only cope with 64 megabytes - which was "loads" in the mid eighties when the ARM was designed. By taking the flags out, a full 32 bits are available for the execution address allowing direct access to 4 gigabytes.

The change to 64 bit is basically an entirely different processor. Load and store multiple registers isn't supported. Neither is conditional execution. There's a sort of conditional but it doesn't work like the ARM we're used to.

Secondly, the ARM32 registers look like this:

ARM32 registers (from arm.com).

There is a definition for a procedure calling standard (APCS) which is used by C programs, but is generally ignored by the OS that uses whatever registers necessary for the many SWI calls. Pretty much the only thing that can be relied upon is that if the V flag is set on exit, R0 will point to an error block.

For completeness, APCS defines that R0 to R3 (called a1-a4) can pass data and be trashed by the function called. Anything that won't fit that needs to be pushed to the stack. R4 to R9 (aka v1-v6) are guaranteed to be preserved. The rest are environment registers (R10/sl = stack limit, R11/fp = frame pointer, R12/ip = usually used as the stack chunk base, R13/sp = stack pointer, R14/lr = link register, R15/pc = program counter); but don't expect the OS itself to honour any of this as it predates APCS.

By contrast, here's what ARM64 (AArch64) looks like:

ARM64 registers (from arm.com).

The X registers are 64 bit. There's a copy set of W registers that are the lower 32 bits.
You'll notice that PC and SP and the PSR are all missing. They exist but they aren't general purpose registers. You cannot change PC by poking an address into it. Therefore this:

LDR PC, [PC, offset, LSL #2]

ADR X0, table
LDR X0, [X0, offset, LSL #3]
BR  X0

So, as you can understand, retaining the existing API is just not viable. Especially if the OS is going to be written in C or Rust or whatever. Anything that isn't another billion lines of assembler.
Which means none of the existing software will work.
Which means all the effort required to design and create a new updated secure 64 bit incarnation of RISC OS is, honestly, ludicrous.

This isn't negative thinking. It's cold hard reality and crossing fingers, squeezing eyes shut and wishing really really hard isn't going to change this.

I would love to see a new OS based upon the concepts of RISC OS but in a way appropriate for the twenty first century, written in a high level language so it can be ported to various different processors (like x86). But given that the Pi3 is now over six years old and we still have no support for the onboard WiFi and Bluetooth is a completely unknown concept to RISC OS, it's painfully clear that the dreams of a 64 bit rewrite are that - dreams. The only thing that's going to change this is cash, and a dose of madness given that Microsoft spaffed a shade under ten billion dollars and failed to make a dent in the mobile phone market dominated by Android and iStuff.

Carrot Cake

Carrot Cake (Betty Crocker).

Just had a big piece and my blood sugar level is right up there with the noctilucent clouds. ☺

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J.G.Harston, 12th November 2022, 17:01

"How come the governments of the world have done practically bugger all in the past twenty six years?"    'Cos Governments. Instead look to non-government actors.  26 years ago my car did 25mpg. Today my car does 55mpg. That's not doing nothing.  In the last 26 years the price of solar panels have dropped something like 20-fold per kWhr output, about 100-fold since the 1970s. That's not doing nothing.  Wind power is about 20 times cheaper than it was 26 years ago. That's not doing nothing.  The UK's carbon dioxide emissions are half of what they were in 1990. That's not doing nothing.

J.G.Harston, 12th November 2022, 17:23

I assisted with writing the in-built ARM64 assembler for C-coded BBC BASIC targetting ARM64 platforms. ARM64 is a Completely Different Processor. It's not ARM with extra bits, it's like 68000 vs 6502. Working out the assembler coding was like learning Czech after a lifetime of Spanish.

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