I'll take it you realise your statement is completely incorrect ;)

...

Lets look at some of the advantages of the DS vrs PSP:

1/ Battery life: Memory access is much more power friendly than a disc-based device

2/ Loading times: Memory has no access/seek time - games will load a lot faster from RAM/ROM than from disc

3/ Manufacture cost: No disc drive is a significant cost saving, not to mention associated shell space & design

4/ DS - lighter/smaller: The disc mechanism is not only "large", its "heavy". Carts are tiny, and the slot weighs nothing.

5/ Game swapping time: Its much easier/faster to flick a DS cart in/out of the slot, than it is to switch PSP games.

6/ Save game support: Its easy to put save memory (EEPROM) on a cart, and impossible on a disk. This makes it very easy for a cart based game to manage its own saves - where a disc based device either needs to save to a general "save card", or non-erasable memory on the device itself. Its harder to program/support saving to a save-card (handle formatting, removal of existing saves, no memory, etc...).

7/ Required RAM (cost, battery use): The DS needs a lot less RAM than a PSP does. The entire data set on a cart is always available (and fast), whereas a PSP needs to load/cache data from the disc into memory - then access it. Extra RAM is basically needed as a cache for data on the disc.

8/ Development ease: Following on from above, this makes it harder to program/optimise a disc-based device. You might need to write background loaders, spin the disc up early, worry about extra battery drain, end up with games "pausing" during a game (while data loads), etc. Disc drives can also deteriorate during the lifetime of a device, effectively killing the hardware. This variable seek time can make it very hard to develop disc based games that stream a lot of data. The DS effectively has unlimited music/sfx/texture space/memory - as it can address all this data instantly. The only concern is with pure optimisation, where data that needs to be accessed more quickly - should be placed in faster memory (with a lower read wait state/time).

9/ Piracy: Its generally a lot harder to pirate cartridge based devices than disc based devices (several reasons).

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The advantages that a disc based mechanism is simple - virtually unlimited amounts of (ROM) data - for free. Now that carts are large enough (1Gbit - or larger??), and they are also very cheap to manufacture in large quantities - close to disc pressing costs - the extra data is the only advantage.

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It may not be obvious, but there are very good reasons for using cart-based memory in a handheld device ;)

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NOTE - its interesting to look at a console based device.

Advantages #1, #4, #5 no longer apply. They tend to have a lot more RAM, so #7 doesn't apply as much either.

Advantages #2, #3, #6, #8, #9 still very much apply - with #8 & #3 being very important.

Once the next generation of carts hit, there is no reason for any device to use disc-based media (except possibly for backwards compatibility).

I wouldn't be completely shocked if the Wii II went back to cart-based media - it would be just the type of unexpected move that Nintendo could make ;)

I'll take it you realise your statement is completely incorrect ;)

...

Lets look at some of the advantages of the DS vrs PSP:

1/ Battery life: Memory access is much more power friendly than a disc-based device

2/ Loading times: Memory has no access/seek time - games will load a lot faster from RAM/ROM than from disc

3/ Manufacture cost: No disc drive is a significant cost saving, not to mention associated shell space & design

4/ DS - lighter/smaller: The disc mechanism is not only "large", its "heavy". Carts are tiny, and the slot weighs nothing.

5/ Game swapping time: Its much easier/faster to flick a DS cart in/out of the slot, than it is to switch PSP games.

6/ Save game support: Its easy to put save memory (EEPROM) on a cart, and impossible on a disk. This makes it very easy for a cart based game to manage its own saves - where a disc based device either needs to save to a general "save card", or non-erasable memory on the device itself. Its harder to program/support saving to a save-card (handle formatting, removal of existing saves, no memory, etc...).

7/ Required RAM (cost, battery use): The DS needs a lot less RAM than a PSP does. The entire data set on a cart is always available (and fast), whereas a PSP needs to load/cache data from the disc into memory - then access it. Extra RAM is basically needed as a cache for data on the disc.

8/ Development ease: Following on from above, this makes it harder to program/optimise a disc-based device. You might need to write background loaders, spin the disc up early, worry about extra battery drain, end up with games "pausing" during a game (while data loads), etc. Disc drives can also deteriorate during the lifetime of a device, effectively killing the hardware. This variable seek time can make it very hard to develop disc based games that stream a lot of data. The DS effectively has unlimited music/sfx/texture space/memory - as it can address all this data instantly. The only concern is with pure optimisation, where data that needs to be accessed more quickly - should be placed in faster memory (with a lower read wait state/time).

9/ Piracy: Its generally a lot harder to pirate cartridge based devices than disc based devices (several reasons).

...

The advantages that a disc based mechanism is simple - virtually unlimited amounts of (ROM) data - for free. Now that carts are large enough (1Gbit - or larger??), and they are also very cheap to manufacture in large quantities - close to disc pressing costs - the extra data is the only advantage.

...

It may not be obvious, but there are very good reasons for using cart-based memory in a handheld device ;)

...

NOTE - its interesting to look at a console based device.

Advantages #1, #4, #5 no longer apply. They tend to have a lot more RAM, so #7 doesn't apply as much either.

Advantages #2, #3, #6, #8, #9 still very much apply - with #8 & #3 being very important.

Once the next generation of carts hit, there is no reason for any device to use disc-based media (except possibly for backwards compatibility).

I wouldn't be completely shocked if the Wii II went back to cart-based media - it would be just the type of unexpected move that Nintendo could make ;)

Those are advantages, but the PSP still sold extremely well in its first year, despite its performance disadvantages. The real reason the DS outpaced it it simply that it had a bunch of killer apps, while the PSP has yet to have a true one.

Where do you get this from?

Just checkec Wikipedia:

BluRay - 36Mbit/sec (4.5 MB/sec)

Flash drives/USB keys:

    Old - 1MB/sec

    New/current - 10-30MB/sec

    Future (spec'd) - 60MB/sec

...

???

No question that optical discs are the way to go re: huge storage space. But they generally suck in terms of read/write speed. 

I'll take it you realise your statement is completely incorrect ;)

... 

Lets look at some of the advantages of the DS vrs PSP:

1/ Battery life: Memory access is much more power friendly than a disc-based device

True

2/ Loading times: Memory has no access/seek time - games will load a lot faster from RAM/ROM than from disc

 True

3/ Manufacture cost: No disc drive is a significant cost saving, not to mention associated shell space & design

Sort of true. Flash is a lot more costly than optical discs, so you transfer costs away from the console to the actual media. If you get beyond the relatively low limit for the sweetspot of flash, you run into N64 type problems of excessively expensive media either driving away developers, or driving up costs of games. 

4/ DS - lighter/smaller: The disc mechanism is not only "large", its "heavy". Carts are tiny, and the slot weighs nothing.

True

5/ Game swapping time: Its much easier/faster to flick a DS cart in/out of the slot, than it is to switch PSP games.

Irrelevant, and also not always true. A terribly designed flash cart system can make this not true. Look at the N-gage. Besides, the times are so small that it makes no difference to anyone, at least that I have ever heard of. 

6/ Save game support: Its easy to put save memory (EEPROM) on a cart, and impossible on a disk. This makes it very easy for a cart based game to manage its own saves - where a disc based device either needs to save to a general "save card", or non-erasable memory on the device itself. Its harder to program/support saving to a save-card (handle formatting, removal of existing saves, no memory, etc...).

True, though has never really been a significant issue in home game consoles. Hard to say what level it would have on handhelds. 

7/ Required RAM (cost, battery use): The DS needs a lot less RAM than a PSP does. The entire data set on a cart is always available (and fast), whereas a PSP needs to load/cache data from the disc into memory - then access it. Extra RAM is basically needed as a cache for data on the disc.

Mostly true. Battery use is a big plus for flash based devices, however the cost differences are negligible. 8MB of cache (or 2 or 16) is a very small added cost. 

8/ Development ease: Following on from above, this makes it harder to program/optimise a disc-based device. You might need to write background loaders, spin the disc up early, worry about extra battery drain, end up with games "pausing" during a game (while data loads), etc. Disc drives can also deteriorate during the lifetime of a device, effectively killing the hardware. This variable seek time can make it very hard to develop disc based games that stream a lot of data. The DS effectively has unlimited music/sfx/texture space/memory - as it can address all this data instantly. The only concern is with pure optimisation, where data that needs to be accessed more quickly - should be placed in faster memory (with a lower read wait state/time).

You really can't be serious on this. Dealing with load times is the big issue that has always been a problem in disc based systems. This is a matter of optimization, and is such a well known and well encountered issue that it is no more difficult for the most part than dealing with any other computer.

9/ Piracy: Its generally a lot harder to pirate cartridge based devices than disc based devices (several reasons). 

No, not really. 

The advantages that a disc based mechanism is simple - virtually unlimited amounts of (ROM) data - for free. Now that carts are large enough (1Gbit - or larger??), and they are also very cheap to manufacture in large quantities - close to disc pressing costs - the extra data is the only advantage.

No, again. They will never be near disc pressing costs. The advantage that discs have is that they have very low material costs, and very low manufacture needs. Flash has fairly low material costs, but manufacture costs are dependent on fabs, which tend to drop costs to a point, and then no further.

It may not be obvious, but there are very good reasons for using cart-based memory in a handheld device ;)

You never addressed piracy, so let me do it for you.

Lets take the DS and the PSP. Both have been exploited to allow 3rd party apps and pirated games. The DS allows playing pirated games via mega-carts, which though probably are not the cheapest thing ever, are easy to find. However, they are very cheap in one way. Due to the fact that flash based consoles will rarely have large games, at least compared to the maximum capacities of flash, many can be fitted onto a mega-cart.

Now lets take the PSP. The PSP was hacked because of one thing - there is a built in boot loader. There really is no reason for it to be there, but its existence means that the MS duo slot can be used to load games, which otherwise would be far more obscure, and much more difficult to manufacture, than the mega-cart system.

Formats only have one inherent effect on piracy - its cost. Everything else comes out to architecture and the planned security system.

NOTE - its interesting to look at a console based device.

Advantages #1, #4, #5 no longer apply. They tend to have a lot more RAM, so #7 doesn't apply as much either.

Advantages #2, #3, #6, #8, #9 still very much apply - with #8 & #3 being very important.

Once the next generation of carts hit, there is no reason for any device to use disc-based media (except possibly for backwards compatibility).

Cost? Capacity? The aforementioned backwards compatability?

I wouldn't be completely shocked if the Wii II went back to cart-based media - it would be just the type of unexpected move that Nintendo could make ;)

If they plan on having a very low maximum capacity threshold, sure, that would make sense. Otherwise it would be insane.