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SDF's original "root" / disk from when we ran Kodak Interactive SVR3 in 1990.

#disk #unix #retro

on a scale of 1 to stuck an arrow in a motor oil bottle trying to make a fishing bow to catch carp to follow a recipe you got from a cookbook you stole from the DPRK, how fucked was your day

bus 在电气工程领域翻译为“汇流排”(来源应该是配电箱中的金属轨),而在计算机领域翻译为“总线”。所以前一个译名只能用来形容电源线,后一个译名只能用来形容数据线,但实际应用时经常混用。台湾一律译为“汇流排”就显得合理多了。

I/O, I/O,
It's off to disk I go,
A bit or byte to read or write,
I/O, I/O, I/O...

USB Battery Charging 1.2 really is a messy hack. It standardizes dumb USB chargers with a current output of anywhere equal or greater than 500 mA.

But how can the device know how much current to draw without any logic or negotiation? BC 1.2 says, the voltage gets lower as the current consumption gets higher. But as long as the voltage doesn't drop below 2 V, any current up to 1.5 A is fair game. Most devices just stay at 500 mA to be safe, but theoretically a device can do "max power point tracking" by progressively drawing higher and higher current while observing the voltage drop, until it found a suitable level...

And it's often said BC 1.2 port can provide 5 V, 1.5 A, it's true but only for a computer data port (Charging Downstream Port). For a charger (Dedicated Charging Port), only 500 mA is mandatory. A charger's voltage is theoretically allowed to drop down to 2 V at 501 mA, and shut down at 502 mA... #usb #electronics

@coelacanthus 這玩意其實滿便宜的……弄到台灣來不到 NT$3000,不過運費就佔了 1500 左右

"Terminally online" is when you log in from a VT220 terminal.

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@niconiconi Why not build a similar circuit using TTL chips? 😀

> When reading data, turn on a very strong pull-up, briefly, immediately after each falling edge of SCK, and then switch to a weak pull-up.

Reduce power consumption of your high-speed open-collector bus with this one weird trick! Battery companies hate it! #electronics

@PeterCxy Most EEs don't work on RF/microwaves and I don't expect them to really have a much better understanding of E&M theory. I'm now waiting for The Signal Path to join this flame war.

Holy crap I can't believe the Veritassium video about EM energy transmission has resulted in an entire flame war over on several EE forums and YouTube channels.

Now here's a first: Using the battery I'm working on to power the #TS100 soldering iron to work on the battery. 🔋 #DIY #LiFePO4 #BatteryBuild #hamradio

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