> I could discuss some subtleties of Bus speeds vs PCI bus speeds butthe short answer is: the PCI bus can transfer 133 MB/sec but the Beige only transfers data at 66 MB/sec thru it's MBoard bus.
Why so slow? It's a 64-bit bus at 66 MHz, which should give it 528 MB/s.
I know the 7500 at least supports interleaved memory access, which means it should be able to peak at 400 MB/s. Is there some problem with the Beige G3 bus or video?
The 7300-9600s only get 50 MB/sec.
Again, are you absolutely sure? What's the point of interleaved RAM if the bus is slower than the 16-bit 25-33 MHz bus (50-66 MB/s) in a Quadra?
I am absolutely sure as I have tested it using 3 different means. The best being a RAM disk and using ATTO's disk transfer tests. Also, GaugePro's RAM speed gives the same numbers. In OS X, XBench's memory tests which test system RAM give the same number. I'm convinced. As for why it's not the theoretical maximum, no computers ever reach that, not even the PCs with their Rambus memory. Older Macs (before the Sawtooth G4s) has particuarly pathetic RAM speeds thanks to a rather outdated RAM chipset. Just moving from a B&W G3 (100 MHz bus speed) to the Sawtooth G4 (100 MHz Bus speed), the RAM speed went from 100 MB/sec to 250 MB/sec. Same RAM. Half of it is from a better memory controller and half of it is from the G4 chip.
Again, I'm just giving you what I have seen, no theory here, just experience.
> BTW: adding a G4 to either Mac will increase it's data transfers by50-60% vs. a G3, so get one!
How does that work? Unless your app is using Altivec, there shouldn't be that much of a difference.
I came across the technical reason why this happens at one point but I can't remember now, but it is real. Using the same tests mentioned above, RAM speed in:
PMac 9500: 200 MHz 604e: 35 MB/sec (same for all CPU speeds if bus speed is constant) 400 MHz G3: 50 MB/sec 400 MHz G4: 80 MB/sec
Beige G3: 400 MHz G3: 67 MB/sec 400 MHz G4: 105 MB/sec
B&W G3: 400 MHz G3: 100 MB/sec 400 MHz G4: 160 MB/sec
> In OS X, the PCI Rage128 is *much* faster than the 7300-9600's "50MHz" onboard video, It is also *much* faster than the Beige's "66MHz" onboard video. I have installed it in both of these machines and it works very well, noticeably faster than the motherboard video on both.
I hate to be a nag, but can you quantify that? What kinds of operations?
On a 1024x768 screen, make a finder window half the size of the screen. Drag it around the screen. on the unsupported Rev A. Beiges and iMacs, the window moving is choppy. Change to Thousands of Colors from Millions and it is *noticeably* less choppy. It's even worse on a 300 MHz Wallstreet. Unusable and annoying. On the Rev B. G3, it's still choppy but better, if you're using a 1/4 screen size window, it's silky smooth. Add a Rage 128 card and it's all silky smooth, no matter the processor speed, window size or bit bepth.
Time to scroll a document in OS X, top to bottom: *a 225,000 character text file in Tex-Edit Plus 4.5 *the same file (in html) in Netscape 7.1 *an 800x600 size graphic duplicated 40x in html in Netscape 7.1
PM G3/500 Beige Rev. A MBoard ATI Rage II 6MB 32 bit - 555 sec (TEP text) - 302 sec (NS HTML text) - 385 sec (NS HTML GFX) 16 bit - 240 - 175 - 119 -
The 32 bit numbers are painfully slow. Completely annoying to use, I'd just as soon go back to OS 9. 16 bit is more tolerable but still too slow.
PM G3/500 Beige Rev. A PCI ATI Rage 128 32 bit - 107 - 232 (no NS graphic here yet) 16 bit - 81 - 130
16 bit (Thousands of colors) and PCI Rage 128 are noticeably faster in all tests. Same for everyday use.
Some other comparison times:
PM G4/450 AGP ATI Rage 128 Pro: 32 bit - 50 - 105 - 75 16 bit - 39* - 53 - 39 *throttled to screen refresh rate (75 Hz), could go faster
PM G3/450 B&W PCI/66 ATI Rage 128
32 bit - 90 (sorry, only TEP text scroll here) 16 bit - 64.5
PBook G3/400 Pismo AGP ATI Rage 128M 32 bit - 110.5 - 174 (no NS graphic here) 16 bit - 83 - 94.5
eMac G4/1000 AGP Radeon 7500? 32 bit - 52 - 71 - 51 16 bit - 41 - 55- 41.5
PM G4/1250DP AGP Nvidia GF4Ti
32 bit - 38* - 46 - 35 16 bit - 38* - 31.5* - 23.5* - even the dual 1.25 speeds up in 1000s *throttled to screen refresh rate (75 Hz)
> Video speed is slower in OS X in slower computers (less than 800 MHzG4) under Millions of colors than under Thousands.
That's not what I observed. Have you actually checked this with the stock 7x00 video?
I haven't used the stock video on my 7500 yet. I'll try that soon (tomorrow if it's not too busy). I can't see that it'll be any faster than the Beige's built-in video.
Mac OS X appears to *always* render in 24-bit, and only dither when actually displaying the pre-rendered windows. Dragging a partially transparent window is particularly impacted by this, because it can't perform any block operations: it has to redither for every frame.
I have no idea about this. Someone else here?
- Tom
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