Monday, February 15


Daily News Stuff 15 February 2021

Did I Do That Edition

Tech News

  • The RTX 3060 is great value at $329 with 12GB of RAM.  Unfortunately it looks like it will sell for anything from $600 to $850.  (WCCFTech)

    Which is not great value at all.

  • Why SELECT * is bad for SQL performance.  (Tanel Poder)

    Actually, all the reasons are obvious and most of them don't matter most of the time.  If you do need just one or two fields, and those fields are indexed, and that query is used a lot, it's worth your time to narrow your field selection.  But far more important to get your database design correct.

  • The Raspberry Pi Pico can output VGA with just a handful of resistors.

    With two cores, 2MB of flash, and 264K of RAM, it's pretty close to a real-world implementation of my imaginary home computer.  Well, it does run at 133MHz rather than 3MHz, and it's 32-bit rather than 10/20 bit, but otherwise.

    Having 8 bit bytes instead of 10 bits means it effectively has less memory, but on the plus side it is much, much, much faster.

    The 264k RAM is broken up into four banks of 64k and two of 4k.  There's a fabric that connects the two cores and the DMA controller to the memory, and the multiple banks let them all read and write to RAM without conflict, if you're careful.

    It also has XIP - execute in place - on the flash memory, so you don't need to load code into RAM before running it.  Not sure how dynamic that is; the tradeoff for XIP is that you can't write to it at the same time.  You have to be running code out of RAM, switch XIP mode off, write your data, and then switch it back on.

    Working my way through the 637 page datasheet right now.

  • Fuck Ethereum.

    Matic on the other hand - now part of Polygon - is Ethereum compatible and seems to actually work, while offering transactions two million times cheaper than Ethereum.

    The one good thing about the sky-high Ethereum prices (both ETH and gas) is that I was able to scrape together small amounts of ETH from secondary wallets at my day job and convert it to what would cost $430,514,016.07 if we wanted to run the same volume of transactions on Ethereum itself.

Definitely Not Tech News

  • Bubble dwellers rise up against....  Everyone else!  (CJR)

    This has to be the most comically unaware piece ever written by a multicellular organism.

  • Though this comes close.  (New York Times)

    The money quote comes right at the end:
    "That’s not what I would have expected from The Times,” she said. "You have the 1619 Project. You guys do all this amazing reporting on this, and you can say something like that?”

Essential Minecraft Mods Video of the Day

There's a strange cat outside.

Disclaimer: Assumes facts not in evidence.

Posted by: Pixy Misa at 09:14 PM | Comments (3) | Add Comment | Trackbacks (Suck)
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1 My understanding of ARM microcontrollers is that the built-in flash is technically XIP, but that's because that's where programs run from.  Running code out of RAM seems to be less common.  (Now, flash that's on external QSPI chips, yeah, that's definitely XIP the way it's normally meant.)
Microchip's got a bunch of ARM line, but the commonly-used hobbyist ones (as demonstrated/pushed by Adafruit) are the SAMD21 and SAMD51.  The latter are faster and have more of everything, and have XIP, whereas the 21 series doesn't.  STM's STM32 series...well, they have something like 7 or 8 different lines, and I think some of them support XIP and some don't.
Anything over about 20-24MHz CPU speed requires wait states when executing code, and it seems to be about 1 wait state added per 24MHz of CPU speed above 24MHz.  There are about a billion registers in an ARM microcontroller; most of them are what we think of as control registers, not general-purpose ones, and doing anything seems to require touching several.
Arduino's neat but it leaves a lot of features and power on the table in favor of making it easier on beginners.

Posted by: Rick C at Wednesday, February 17 2021 01:07 PM (pxvtu)

2 Looks like the Pico has a 16k XIP cache, which should solve the wait state problem, as long as all your data fits in RAM.

Posted by: Pixy Misa at Wednesday, February 17 2021 02:09 PM (PiXy!)

3 It looks like a lot of them have a certain amount of L1, yeah, at least once you get past the $1 or so mark. smile

Posted by: Rick C at Thursday, February 18 2021 04:43 AM (2Mei2)

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Apple pies are delicious. But never mind apple pies. What colour is a green orange?

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