Looking Closely at the Restrictions of Linux on the PS2

Hal-kun writes: "I wrote an interesting article about Sony's upcoming Linux distro for the PS2 and some intellectual property concerns I have with it. It's an intresting look at how Sony limits the ability to have full access to the system, yet being able to keep it under GPL."

Comments

Re:how they limit it

[Hougaard]

A couble of comments:

1) Its actually not "bad areas" that Sony is using with PS2 discs. They have encoded a sort of sub-signal onto the disc that bruners cannot recreate and more important, nor can asian "copy shops".

2) The PS1 discs has a error written into the TOC but CloneCD (aand others) deals with this without problems.

3) Developers can actually buy CDR's at Sony with the copyprotection on, so they can burn discs to test on non development equipment.

4) Sonys DVD-ROM's has the same copyprotection buildin as the CD's. So even with a DVD-R (Burned on the A03) you cannot boot with a modchip.

Sync on green....

[wowbagger]

I keep seeing people who don't understand what "sync on green" is, and this guy is one.
<Electronics_lession>
For *any* monitor, it is required to know when a horizontal scan line starts, when it stops, and where the top of the screen is. This information is called sync, and is seperate from the video data that paints the image.

In a normal, modern monitor, five signal lines go to the monitor:

1. Analog red
2. Analog green
3. Analog blue
4. digital vertical sync
5. digital horizontal sync

Now, the hsync line is in one state while the monitor is scanning across the display, and another state during the time the electron beam is being swept back across the display (the horizontal retrace interval). The vsync line is in one state when the screen is being painted, and another when the beam is brought back to the top of the screen (the vertical retrace.)

Now, in older monitors, to save signal lines, they used a technique call "sync on green". During the normal horizontal scan, the green line was at a voltage between 0V and 1V, with 1V being full on green, and 0V being no green. During horizontal retrace, the green line went to -0.5V to signal sync. During vertical retrace, the green line was -0.5V during the whole scan line, and went to 0V during the horizontal retrace. By suitable filtering and phase-lock techniques the actual sync signals were recovered from this. Thus, a sync on green monitor required only 3 signal lines.

Now, if you take a normal monitor, and connect it to a sync-on-green system, the monitor's sync inputs will be undriven. A multirate monitor will simply turn off it's drive to the screen, assuming the computer is turned off.

Sync on green has nothing to do with "synchronizing the red and blue signals with the green" - they are synchronous in time already.

Your best bet for such things is to go to a computer graveyard, and try to find an old monitor. Many older monitors would do sync on green as well as normal discrete sync.

</Electronics_lession>
<Rant>
What I don't understand is why everybody is getting so excited about this. Sony is locking you away from the hardware - without a massive RE effort you are not going to be able to do much with this system. For the price of the PS2 and the Linux distro and hardware you could by far more useful devices (until somebody cracks all the hardware protection). Assuming somebody does manage to get raw HW access, Sony will make that person disappear in a puff of red smoke.

Why don't we all just ignore these people until they learn to play nice with others? Look at the Atari 2600, the Apple ][, the PC. They were successful because people could hack them. Sony and Apple learned the wrong lesson ("We must have total control! Nobody BUT US CAN MAKE MONEY OFF THIS") rather than the right lesson ("Hardware like parachute - works best when open.").
</Rant>