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Comment Re:You're testing wrong (Score 2) 177

Yeah, I was going to say, 40ms seems a bit out there. If you consider a touch typist typing 100WPM, that's about 8.3 characters/second, or about 120ms / character. You may think 40ms is fast enough to accommodate that, but not really. Typing is bursty by nature, and so many of those consecutive keystrokes will come close together. If you scan too slowly, you might see two keys "become active" on the same scan, and end up reordering them. At 40ms, that seems entirely likely for a touch typist at 100WPM.

10ms seems far more reasonable.

Comment Re:You're testing wrong (Score 2) 177

So, GGGP was less wrong than stated, but for the wrong reasons. Huzzah! That is a rather strange defense. "I thought I was supposed to go south, when actually I was supposed to go north. But, I misread the roadsign and got on a road that goes northeast, so I ended up not too far from my destination. See? I'm not a bad navigator!"

Anyway, in the interest of actual analysis:

Let's go at the low end: 10kHz. And let's pick a beefier keycode, say "R CTRL", that has a 2 byte scan code. No, we're not going to benchmark the hilarious pause key. Get real. The vast majority of the scan codes are 1 byte anyway.

The time to send a key down event should be 2 bytes * 11 clocks, or 22 clock periods at 10kHz. That's 2.2 milliseconds. The time to send a key-up event should be 3 bytes * 11 clocks => 3.3 milliseconds.

Both of those seem pretty fast. The OS itself, though, and whatever layers there are between the PS/2 connector and the OS, will add their own latency. But in a race between a PS/2 keyboard and a USB mouse? I think they're going to both be well under 50ms in any case. 50ms is 20Hz, which is "Intellivision games from the late 70s" speed.

Comment Re:Clarification (Score 1) 211

I think it's probably fine to store non-empty cells as objects, as long as you use something like the Flyweight pattern to avoid carrying too much baggage in each cell. It makes for a fine user interface, I'm sure.

To really get good recalc performance, though, you really need to drag the cell dependence graph out of the grid and treat it like an actual program. Once you do that, you could actually JIT the computation represented by all those cells. If you're really walking the object forest for every recalc, you'll never speed up.

Comment Not too surprising (Score 5, Interesting) 164

Someone else (who I think I saw here on Slashdot the last time Voyager was mentioned) had a great analogy for what we're likely seeing. I can't take credit for this at all, but I think it makes a lot of sense.

Suppose we're a small probe, making our way off an island, down the beach, and into the ocean. All we have is a wind-speed detector, and a water detector. As we near the water, waves start lapping over us. When they do, our wind-speed detector says "no wind", and our water detector says "we're wet." Have we entered the ocean yet? The answer is "not quite, but we're really darn close."

It doesn't seem surprising to me at all that the boundary neither perfectly uniform, nor stationary in time. I think we'll be in this transition band for a while.

Comment Re:Equal rights (Score 1) 832

Even if this is discrimination, I'm also not clear that this is discrimination against fathers. It might well be discrimination against mothers. Fathers only have to spend eight weeks caring for the new baby. Mothers have to spend twelve.

After which you send it to the centralized child care facility, so the child is never a burden to either parent ever again?

I'm pretty sure both parents are on the hook for child care for as long as the child is a child. The issue is whether they're also on the hook for going to a job other than raising their child.

Comment Re:Equal rights (Score 1) 832

My high-tech employer only offers TWO weeks paid paternity leave. TWO. Not the generous eight that Yahoo! offers. That was probably considered progressive in the US in the 60s, but seems hopelessly behind the curve in high tech today. One of my coworkers took an extra two weeks out of his own vacation time to spend a total of four paid weeks with his newborn daughter.

I personally have 8 weeks of vacation time built up, because work keeps me busy enough that I never feel like I can take the time I'm entitled to off. I don't even feel like I can ask for the time off, and it's technically already mine. The culture works against it. We're a country of workaholics, and we're made to feel bad when we ask for a little space.

If we really wanted to do things "right" here in the US, I'd have to ensure I built up a big enough cushion that my wife and I could remain unemployed (and thus, unpaid) for a couple years. And then, hope I could find a job after 2 years out of high tech. Hmmm... yeah, seems unlikely. Or, at least, feels unlikely, even if perception doesn't match reality.

Ah, the American dream: To make enough money that you no longer have to work for a living. For the vast majority of us, it will always remain a dream.

Comment Re: Equal rights (Score 1) 832

Why it is that every time the moron politicians of the world reach for the cutting budget scissors they cut education, healthcare and social programs?

Hint: It's usually a rich politician whose family and friends wouldn't suffer the cuts directly. They sell it by painting the beneficiaries as slackers that are a drain on society, as opposed to the reality. These things solidify the very base of society.

Net result? An ever widening chasm between the haves and the have-nots. That chasm strains the very notion of society.

Submission + - Under the Smogberry Trees: Kickstarter aims for Dr. Demento Documentary (

Mr Z writes: A favorite of geeks, nerds and quirky folk everywhere, Dr. Demento has been a fixture since 1975, bringing funny, demented music to us all. Dr. Demento both inspired and helped launch many artists, including such diverse talents as Weird Al Yankovic and Richard Cheese.

The group at Meep Morp Studio are working to put together a documentary about both the good Dr. himself as well as his alter ego, the globally respected musicologist and historian Barret Hansen.

The catch? They have a a Kickstarter here that still has 40% to go in the next 5 days. That's a pretty tight deadline. But, if even a small fraction of Slashdotters that have enjoyed Dr. Demento over the years pitch in a nice dinner's worth of dollars each, this documentary will get made.

Comment Re:Missing Option (Score 1) 135

You either needed a PEB + Editor/Assembler (which I didn't have), or you could by the Mini Memory cartridge which comes with the Line-by-Line Assembler (which I did have) that left you 768 bytes free to program at location >7D00 (out of 4K total battery-backed memory)

You certainly could not, however, program assembly code on an unexpanded TI-99/4A. You needed at least the Mini Memory cartridge.

TI Extended BASIC didn't have PEEK and POKE in the same sense as other Microsoft BASICs. In other computers, you could literally read and write any location. TI Extended BASIC let you PEEK certain locations, but not really POKE anywhere.

The Mini-Memory did add a PEEKV and POKEV that let you manipulate VDP RAM, but again, that required the Mini Memory cartridge. (I don't know if E/A also provided anything like that; I didn't have E/A.) And if Mini Memory's plugged in, you don't get TI Extended BASIC.

Comment Re:You're a contractor. Your "secrets" are yours (Score 2) 292

There are a lot of good points in this thread. It's worth noting that there's no direct replacement for experience. You bring N years of experience to the job, and the only thing that can bring you N years of experience is N years of doing the job. While you can teach some the broad lessons (and, I would say, teach them specifically in the context of this app; you're not a professor and you're not teaching a class), there's no replacement for experience.

When I was fresh out of college, I could write programs that did very interesting and useful things. Now it's *mumblety* years later, and I know for a fact I would write my programs far differently now, with generally much better outcomes in maintainability, scalability and flexibility. Much of that was learned through trial and error—ie. experience. That only comes with time and practice.


Spinning Black Hole's Edge Rotates At Nearly the Speed of Light 227

astroengine writes "Astronomers have directly measured the spin of a black hole for the first time by detecting the mind-bending relativistic effects that warp space-time at the very edge of its event horizon. By monitoring X-ray emissions from iron ions (iron atoms with some electrons missing) trapped in the black hole's accretion disk, the rapidly-rotating inner edge of the disk of hot material has provided direct information about how fast the black hole is spinning. Astronomers used NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) — that was launched into Earth orbit in June 2012 — and the European observatory XMM-Newton measured X-ray radiation as a tool to directly infer the spin of NGC 1365's black hole. 'What excites me is the fact that we are able to do this for the very massive black holes at the centers of galaxies but we can also make the same measurement for black holes in our galaxy ... black holes that resulted from the explosion of a star ... The fact we can extend this from billions of solar masses to 10 solar masses is pretty cool,' Fiona Harrison, professor of physics and astronomy at the California Institute of Technology, Pasadena, Calif., and principal investigator of the NuSTAR mission, told Discovery News."

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The flow chart is a most thoroughly oversold piece of program documentation. -- Frederick Brooks, "The Mythical Man Month"