OK, people have been spouting this that an the other thing about PS2 and DC.
Few people have bothered with nailing down any specifics, and making good
comparisons, so here I go. What entails is a complete run down of the
technical specifications of both machines, and personal notes and
explanations of each section. I encourage anyone who wants to enter the "My
system is better", to relate to this as a basis, and add their machines (I
don't have any N64 specifics yet, nor anything on the Dolphin). I don't know
if this should be expanded to be an end-all be-all comparison, so for now,
I'm just limiting to the two major ones in the immediate future.
PlayStation2 (PS2) vs. Dreamcast (DC)
Suggested Retail Price (Japan)
PS2: 39,800 Yen (March 4, 2000, estimate about $299US by release in late
2000)
DC: 19,900 Yen (Current, estimate about $149US by early/mid 2000)
Notes: Sega's hardware is much simpler, and their profit margin is much
higher on a per machine basis. Expect Sega to bring down prices upon PS2's
launch.
Media:
PS2: CD (660Mb) DVD (5.4Gb)
DC: CD (660Mb) GD (1.2Gb)
Note: While GD has more space and is cheaper to produce than CD's, DVD
has the edge is just raw amount of space. When double density DVD's come
around, the capacity will grow to 8.5Gb. Double sided DVD's will still
require flipping, so is no less convenient than having two GD's.
Interfaces:
PS2: 2 x Controllers, 2 x Memory Cards, AV Output, Digital Output, 2 x
USB Ports, I-Link (IEEE1394), Type III PCMCIA
DC: 4 x Controllers (each controller has two spaces for add-ons), AV
Output, Serial I/O, Expansion Connector
Note: The VMU is a great idea, and the four controllers is a must in
current hardware design. Some people speculate that Sony may up the number
or ports to four, but nothing has officially come forth. The USB, IEEE and
PCMCIA ports add additional complexity and cost to the PS2 and pulls it a
bit further away from the "pure" console market. The Sega expansion
connector is more flexible than PCMCIA and far less costly due to larger
packaging. The to be released Zip drive adds USB to the DC, as well as huge
amounts of storage space.
CPU:
PS2: 128-bit "Emotion Engine*", 294.912 MHz (300MIPs, 6.2GFLOPS), 32-bit
MIPS R4K/IOP (50MIPs)
DC: 128-bit Hitachi SH4 200MHz (360MIPS, 1.4GFLOPS)
Note:The 6.2 GFLOPS in the Emotion Engine (EE) accounts for the ten
multiply and accumulate units, four divide units and two vector units, which
artificially inflates the FLOPS count, which is normally measured across all
fpu functions, including transcendental. This limits the PS2's floating
point ability, even with regards to 3D geometry. Advanced math routines are
beyond the simple multiply and divides, slowing performance in regards to
anything non-3D (like physics modeling, and AI routines). The somewhat
poorer MIPS performance is enhanced ever-so-slightly by the MIPS processor.
The SH4 is a tad faster in integer performance, but suffers in the math
department. Like the EE, the SH4 incorporates a multiply-and-accumulate
engine, but only one. It has a vector engine as well and a more
"traditional" FPU, allowing for greater flexibility. Additionally, unlike
the EE, very little of the 3D processing is done by the CPU. See table:
Bezier Curve Conversion into polygon strips: PS2 CPU, DC CPU
Transformation & Rotation in 3D space: PS2 CPU, DC CPU
Perspective Transformation (3D to 2D conversion): PS2 CPU, DC PowerVR
Clipping (screen edge) and Sorting (to reduce z-buffer abuse): PS2 CPU,
DC PowerVR
Lighting: PS2 CPU (basic lit surfaces, software volumes), DC PowerVR
(also volumetric lights and shadows)
Fog: PS2 CPU/GS (hardware alpha blending, mask generated by CPU), DC
PowerVR (including volumetric effects like smoke and variable fog)
Filtering, Rendering, etc: PS: GS, DC: PowerVR
As you can see, the PS main CPU has to do everything except the final
rendering. This means that the SH4 is freed up to do other tasks, while the
EE spends a lot of it's time handling 3D geometry. For more information, see
the graphics section below.
RAM:
PS2: 40Mb Total; (32Mb Main Memory, 4Mb Video "Cache", 2Mb Sound, 2Mb
IOP Memory)
DC: 26Mb Total; (16Mb Main Memory, 8Mb Video, 2Mb Sound)
Note: The PS2 has the edge here, allowing for more complex games to be
programmed. The 2Mb IOP memory is for the PS MIPS CPU. The only weak area is
the 4Mb of video "cache". Since the PS2 uses z buffers, the largest screen
is about 640x400 (not 480, like the Dreamcast) at 32-bit colour. This would
also preclude the ability to hold texturemaps, since a 640x400x32b screen
would eat up the whole 4Mb. Thus textures have to be offloaded to system
ram, and pulled up as they are needed. This is potentially a big slow down,
since the EE and GS must now fight for system ram. The bandwidth required
for effective rendering can eat up the whole bandwidth available to system
RAM, locking the CPU out. This is but one area where the PS2 is hard to
program for. At 512x384x32b the PS2 uses 1.5Mb of video RAM for the frame
buffer and z buffer, allowing for more texturemap space. Expect a lot of
early PS2 games to be lower res until programmer can better deal with bus
contention.
The DC employs 8:1 texture compression, and has twice the video RAM.
Additionally, the PowerVR does not use z-buffers, and eliminates over draw,
reducing bandwidth requirements (see below for more details). At 8Mb, a
640x480x32b image consumes 1.2Mb of video RAM, leaving 6.8Mb for textures
and shape data. With compression, this could easily be equivalent to 56Mb of
video RAM. The PS2's implementation of compression is limited to MPEG2 only,
and uses considerable CPU resources, so it is not effective for in-game
animated textures, or texture compression.
Drive:
PS2: 24x CD-ROM/4x DVD
DC: 12x CD-ROM
Note: PS2 wins here, being twice as fast as the DC. Keep in mind though,
that on PC's, CD's rarely have the opportunity to achieve 24x, let alone
12x. The DC's CD as 12x is fast enough to make load times very small (Sonic
Adventure levels load in about 1-2 seconds), to the PS would reduce it to
about 1/2 to 1 second for similar amounts of data. In DVD mode, the transfer
rates are a but higher (about the same as a 44xCDROM), cutting loading times
to the sub-second. Expect many first-gen PS2 games to be released on CD and
"backwards compatible with PS" (ie: game is made for the PS, with PS2
improvements)
Sound:
PS2: 48 Channel, SPU2 (Yamaha?)
DC: Yamaha "Super Intelligent Sound Processor", 64 Channel, Hardware 3D
sound
Note: Little is known about the PS2's sound engine. Though I would
expect, that under ordinary operation, the MIPS processor handles DSP and
sound effects, whereas the DC's sound chip has onboard support for 3D sound,
and DSP effects. The PS2 would ultimately be more flexible. As an aside,
note how the older CPU is delegated to I/O and Sound. Sound familiar (hint:
Motorola 68000)
Graphics:
PS2:Sony Custom Graphics Synthesizer, 32bit colour, 32bit Z-buffer,
Built-in functions (texture mapping, bump mapping, linear fogging,
alpha-blending, bi- and tri-linear filtering, mip mapping, anti aliasing,
multipass rendering up to 16 channels), 2.4gigapixel fill rate (pixel
overdraw reduces practical rendering speed to less than 600fps), 75 million
polygons per second peak* (no effects, "very small polygons"), 25million
polygon's per second (effects enabled, 48-pixel quad), 18.75 million 2D
sprites per second (8x8 pixel), 1280x1024 max resolution
DC: NEC Power VR-DC (special edition for Dreamcast), 32-bit colour
(optional 16-bit dithered output to frame buffer), no z-buffer memory
needed, Built-in functions (full 32-bit floating point geometry setup,
hidden surface removal, tiling, modifier volumes, translucency, 8:1 texture
compression. perspective correct deferred texturemapping with ARGB gourad
shading, specular highlights, environmental mapping, full scene
anti-aliasing and supersampling, bi- tri- and ansiotropic filtering, YUV-RGB
colour space conversion, ROP and text and line primitives, motion
compensation acceleration, colour key overlay, per pixel table fog,
multitexturing), 200megapixel fill rate, 3.5 million polygons per second
peak (effects enabled, 100 pixel quad), 1600x1200 max resolution. Notes:
memory bandwidth requirements are independent of polygon count or polygon
per second figure, and between three to ten times lower than traditional
three-dimensional systems (i.e.: PS2), texture compression adjusts bandwidth
requirements by up to six times lower than traditional systems (i.e.: PS2).
Note: Egad. Well to summarize, the PS2 handles everything needed to
render 3D graphics, and that's about it. The EE sends polygon data (three or
four 2D coordinates, and pointers to texture, bump, light and dark data),
and the GS pumps the data to the screen. It offers little in effects, and
places the burden of rendering on the CPU. The 75 million polygon figure is
out-to-lunch, since the EE at full bore is unable to provide new polygon
position and data fast enough (about 66 million at no detail). Since the
bottle-neck is with the processor, I'll take a moment here to discuss this
further. The EE can render 36 million polygons with some effects on (though
it still doesn't do many things the PowerVR can). This is full bore, which
means the CPU is doing nothing but dumping polygons. With game physics and
AI bundled into the mix, expect polygon counts to drop. More complex games
will hurt more in the graphics department. Of course, the polygon count,
even in the potential worst case (all bezier surfaces, 50% CPU spent on AI
and physics) is still faster than the PowerVR. In fact, about twice as fast.
What does this mean. Well, look at the current DC game models. For every
straight edge you can see, subdivide it once (so that each edge is broken
into two), and that's the detail improvement you'll see. Pretty substantial?
Of course, as game developers make better use of the CPU(s), I'd expect
polygon performance to increase.
On the DC or PowerVR's side, the 3.5 million polygon count allows for
scenes of up to 58,000 polygons (about 4x's the detail in Quake 3). At
640x480 the pixel fill rate can redraw the entire screen at 650 fps. Unlike
the EE/GS, the PowerVR only draws a pixel once per frame. This is called
overdraw, and in Quake 2, costs performance of about 1/3 (that is, each
pixel is typically redrawn about three times). The PowerVR also handles
subsampling and has the video ram to do so. Games could be rendered
internally at 1280x960, and down sampled to 640x480 for television output.
This produces images with less pixelization. 8:1 texture compression
increases the effective amount of video ram for storing of textures,
allowing for incredibly detailed characters and backdrops (something the PS2
may have trouble with, or eat up valuable system ram). As noted earlier in
this text, the fpu that is on the PowerVR eliminates several steps from the
CPU's burden. And most importantly, while currently no game is known to
fully support this, the DC can use modifier volumes. Effects such as light
beams, shadows, lasers, and glowing suns are all possible with this, which
would otherwise require significant CPU effort, and visual tricks to
accomplish (such as using a flat polygon for fake shadows). Also, the
polygon per second count is for drawn polygon's only. Polygon's that are
buried under other ones are not drawn at all, nor are polygons that are to
far left/right/up/down to be seen on screen, nor are polygons which are
facing the other way (about half).
Bonuses:
PS2 will come with an 8MB Memory Card
PS2 can play DVD movies
PS2 is backwards compatible with PS (though old peripherals only work
with old games)
DC includes a 56K modem
DC uses "VMU"s allowing for micro displays on each controller, and mini
games (ala Gameboy)
Summary:
The PS2 can handle 1280x1024 that it can't display due to video RAM
limitations, has a rendering chip that can render more polygons than the CPU
can create and with a faster framrate than is supported by any monitor with
enough detail that each pixel can be potentially realized by a single
polygon but lacks the memory to handle such detailed models. An overpowered
brute in some respect, yet obviously crippled in others, the PS2 is a
complex beast, and will take a great deal of time before programmers can
utilize even a small amount of it's power. In comparison to the 16-bit
generation, this really reminds me a lot of the Sega Saturn, which to was a
complex beast to program for.
The Dreamcast is simple and elegant, and easy for programmers to
understand, and yet has several treasures yet to be realized. A shallow
learning curve with a long road makes for light travel. Of course, the
machine does lack the raw power that the PS2 has, though each component is
more balanced. While seeming limited in performance, the DC can potentially
display a screen full of 6-pixel polygons at a resolution of 640x480 at
60fps, with power to spare for special effects like real shadows and volume
lights. Additionally, unlike the PS2, the DC has the video memory to handle
such complex models, at such high resolutions.
Fundamentally, the success or failure of the Dreamcast and Playstation2
can be boiled down into these points:
1. Do developers support the machine - this killed the Saturn as it
was selling poorly due to high retail cost, and was vary hard to program
for. Only Sega themselves could make a game that pushed the polygon's like
VF2. Most developers greatly dislike the steep learning curve of the PS2,
though they do like the power available. Some developers have stated that
the PS2 compares on-par with the DC, or slightly better (over all), so the
developer community is split right now.
2. Can the public afford the machine - price point is very important
to everyone except hardcore games and loyalists. Sure, there will be people
that will spend the $300 (...) on the PS2, but it wasn't until the original
PS dropped in price in the US that it really sold well. PS2 will be
expensive, and for the Christmas 2000 season, about twice the cost of a
Dreamcast (retail). The profit on each PS2 sold will probably be negative to
sell the machine at the $300 point, which means the PS2 will never be able
to break the sales record of the fundamentally more (at all) profitable
Dreamcast.
3. Does the public like the machine - games sell systems, obviously.
The cry form the PS2 towards backwards compatibility and that the PS2
already has a library of 600 games is crock. No one will buy a game machine
for $300 when all the identical games can be played with a $100 one. PS2
specific games may be few and far between at first, until developers figure
out how to program the machine
Oh yeah, and finally, the Dreamcast is grey. No grey machine has ever
failed :)
David Cousins
PS: Every thing is measured by the next milestone. I, and everyone else,
should expect as much effort into arguing their case as I have done. This
only took a few hours, so don't complain. People who present illogical "blah
blah is better than blah blah" should be ignored unless they can present
some degree of reason. I believe that I have done so.
