Follow Slashdot stories on Twitter


Forgot your password?
Trust the World's Fastest VPN with Your Internet Security & Freedom - A Lifetime Subscription of PureVPN at 88% off. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. ×

Comment Re:Missing theory (Score 1) 45

A view Russian probes got lost while flying over HAARP, I think Phobos Grunt was the most recent one. The theory is that their electronics was grilled by these high-power transmitters. This one actually makes sense though.

This was obfuscation on the part of the Russians. According to the failure report issued by Roscosmos there were other reasons, including use of non-space-qualified components that were susceptible to radiation damage, and insufficient ground testing.

Comment Will it be entertaining? (Score 3, Interesting) 40

I think in the early days, these races might be entertaining.

I can imagine that eventually some kind of optimum strategy may evolve and all the teams use it, and then the cars will all do the same thing and the race will be boring. But in the early days, with people trying different strategies, stuff might happen that is interesting to watch.

I remember back at my first job, we found some kind of game where you wrote a program to control a robot tank in the game, and the whole game was to have matches between people's programs. The programming language was simple and there were APIs for things like "throw out a radar ping", "turn tank", "rotate turret", "fire gun", "check to see if tank is damaged", etc. There were many different strategies available: you could write a tank that never checked if it was being damaged, but just drove around crazily all the time to be hard to lock onto; you could write a tank that, when it got a ping, would try to lock onto that tank and follow it and keep shooting it until it was dead; you could try to write a balanced tank that would check if it was damaged and evade if so, try to figure out where other tanks were and just send shots in that general direction, etc. We had great fun with it for a while, and then one of the developers (not me, sadly) wrote a tank program that was dramatically more effective than all the others. The fun died away when it became "watch Rich's tank destroy your tank and all the others".

The question is whether Rich's program was actually optimum in some sense (did the best possible according to the simple simulation rules) or whether we could have beaten it if we had been more clever. I'm not sure. I wish I had copies of the source code to all the bots from back then, now that I have a lot more experience in software development and I might get more out of the game.

This was years ago and I couldn't tell you what game it was exactly, but there are plenty of programming games around.

Comment Re:The publisher refuses to take my money (Score 1) 159

How does it hinder it in these particular cases? The things you listed aren't exactly classics.

Who decides what are "classics"?

Find me a lawfully made copy of these on a video format popular in the United States.

So buy it on DVD

From the linked page: "Region: Region 2 (This DVD may not be viewable outside Europe. Read more about DVD formats.)" Region 1 DVD is popular in the United States. Region 2 DVD is not.

Comment Re:Super NES address space is far from linear (Score 2) 157

Different aspects of mirroring have different purposes.

Mirroring is the result of incomplete decoding of the address bus. Incomplete decoding saves a gate or two and usually doesn't hurt anything. Shaving pennies off the replication cost of millions of Game Paks could increase profit.

The 65816 requires the reset and interrupt vectors to be available at $00FFE0-$00FFFF in order to start up. If ROM is not mirrored into $00FFE0-$00FFFF, the system will hang at startup.

Only ROM at $808000-$FFFFFF is set up for fast access. The rest of ROM ($008000-$7DFFFF) is hardwired for slow access so that the 65816 can retrieve its reset vector before the memory controller is configured. So programs run memory controller initialization somewhere in $000000-$7DFFFF and then jump to $808000-$FFFFFF once they've initialized the memory controller.

I/O and a portion of RAM are mirrored into $00-$3F and $80-$BF so that the CPU can access a subset of data in ROM, data in RAM, and I/O without having to either change the data bank register or use 24-bit addressing all the time. Unlike the 8086, the 65816 doesn't have "prefixed" instructions that can change which segment is used. Instead, the data bank register must be explicitly reloaded in order to use 16-bit addressing, which is slightly faster than full 24-bit addressing. In addition, several 65816 addressing modes are hardwired to use bank $00, particularly those dealing with the base pointer (D) or stack pointer (S).

See Fullsnes or Super NES Development Wiki for more information

Comment pokey at the jewelry store (Score 2) 62

pokey at the jewelry store

There. It's my favorite Pokey strip. It's also the only Pokey strip I like. I don't really get the love for Pokey... I don't get the love for Zippy the Pinhead either.

I really do like this one. The increasing aburdity of the situation unfolds with IMHO perfect comic timing.

Comment AWS is cheap but not free (Score 1) 141

Video at 720p takes about 2 Mbps (source), or 2 Mbps * 60 s/minute * 1 GB/8000 Mbit = 0.015 GB/minute. Data transfer out of AWS costs 9 cents per GB plus tax (source). If a 10-minute (0.15 GB) video goes viral (which used to be called getting Slashdotted) and gets 10,000 views, that could result in a big AWS bill: 0.15 GB/view * 10,000 views * $0.09/GB = $135. Is the average person expected to afford that without running his own ads?

Comment Super NES address space is far from linear (Score 4, Informative) 157

The part of the Sega Genesis memory map allocated to the cartridge is a linear sequence of bytes from $000000 to $3FFFFF. The part of the Super NES memory map allocated to the cartridge is not. See my diagram of Super NES address space.

The 65816 divides its 16 MiB address space into 256 banks, each 64 KiB in size. In order to make certain addressing modes more efficient to use, the Super NES divides up cartridge ROM address space as follows:

  • Bank $00-$3F: Second half (32 KiB, $8000-$FFFF)
  • Bank $40-$7D: Whole bank (64 KiB, $0000-$FFFF)
  • Bank $80-$BF: Second half (32 KiB, $8000-$FFFF)
  • Bank $C0-$FF: Whole bank (64 KiB, $0000-$FFFF)

The "HiROM" mapping (mode $21 or $31) is a linear sequence of bytes from $C00000 on up. Because of incomplete decoding of the address bus, the second half of each 64 KiB bank is usually mirrored into $808000-$80FFFF, $818000-$81FFFF, $828000-$82FFFF, ..., $BF8000-$BFFFFF. In addition, banks $80-$FD are mirrored into banks $00-$7D, so that the 65816 CPU can find the reset vectors at $00FFE0-$00FFFF (which is mirrored from $80FFE0-$80FFFF). Usually, battery save memory is at $306000-$307FFF, $316000-$317FFF, ..., $3F6000-$3F7FFF.

You might notice that everything in the above skips banks $7E and $7F. That's where the Super NES puts its 128 KiB of RAM, with the first 8 KiB mirrored into banks $00-$3F and $80-$BF. It also mirrors the memory-mapped I/O ports associated with the CPU's memory controller and the Picture Processing Unit (PPU) into banks $00-$3F and $80-$BF. They are made accessible through all these banks so that the same value of the Data Bank Register (DBR), analogous to the Data Segment (DS) register on 8086, can see RAM and ROM at the same time.

The "ExHiROM" mapping (mode $25 or $35) has two linear sequences of bytes: from $C00000 to $DFFFFF and then from $400000 to $5FFFFF, which get mirrored down into the second half of $80-$BF and $00-$1F respectively. Only the largest games, mostly exclusive to Japan such as Tales of Phantasia, use ExHiROM.

The "LoROM" mapping (mode $20 or $30), more common on early games, does not connect A15 out of the system to the ROM. This means it uses only the second half of each bank: $808000-$80FFFF, $818000-$81FFFF, $828000-$82FFFF, ..., $FF8000-$FFFFFF. Banks $C0 through $FF mirror the 32K of data in that bank into both halves of the bank, and banks $00-$6F are a mirror of banks $80-$EF. Usually, battery save memory is somewhere in $700000-$77FFFF.

Cartridges use either slow or fast mask ROM. Modes $20, $21, and $25 are "slow ROM", where the CPU slows down slightly in order to allow use of cheaper 200 ns ROM. Modes $30 and $31 are "fast ROM", which needs 120 ns ROM that was more expensive in the early 1990s. Mode $35 has fast ROM for the $C00000-$FFFFFF region but slow ROM for the $400000-$5FFFFF region.

Slight differences in address decoding in each cartridge lead to differences in which address ranges actually contain mirrored ROM (as opposed to open bus) and which address ranges contain battery-backed RAM. Furthermore, some coprocessors included in cartridges can change this mapping at runtime.

Comment Re:The publisher refuses to take my money (Score 1) 159

Then you are not ENTITLED to watch it

How does this lack of ENTITLEMENT "promote the Progress of Science and useful Arts"?

Wait a few more years and it will all be worked out

This is not practical for copyright, which is designed to subsist for a period exceeding one human lifetime.

Comment The publisher refuses to take my money (Score 2) 159

Today with all the options available 'because I can't get it any other way' is a crock

Sometimes I can't get it because the publisher refuses to take my money. Try this exercise: Find me a lawfully made copy of these on a video format popular in the United States.

  • The TV series Spartakus and the Sun Beneath the Sea (the English-language dub of Les mondes engloutis)
  • The film Song of the South (Unless you think LaserDisc was "popular")
  • The film Pinocchio and the Emperor of the Night (Do you consider VHS still a viable option?)

Slashdot Top Deals

If entropy is increasing, where is it coming from?