<strong>That would be cool, but I don't see 1GB+ (which will be standard some day) SRAM ever being affordable to mere mortals.
SRAM should have better latency than SDRAM, but I read somewhere that the SRAM used by the G4's L3 cache had a 40 cycle latency. That sounds high. I didn't think even SDRAM had such bad latency.
Am I wrong or is Apple, using the cheapest RAM they can find for their PowerMacs?</strong><hr></blockquote>
1GB of SRAM affordable? Probably not, which is why I say its in the future. Yet I still daydreamed about it back in my intro computer architecture class. Ahhh....
Find me stats on the SRAM's latency and I'll buy it. True, Apple historically skimps on RAM and overcharges, but I have no data on SRAM in Apple's history. Theoretically, the SDRAM would have a lot higher latency than any SRAM. As I recall (though it has been a while) you'd have to design SRAM pretty poorly to make it as latent as SDRAM. (This is an open invitation to anyone who ACTUALLY knows better to correct me--though politely please I'd like to figure this all out and discuss...not argue)
CPU caches: The G4+ PowerPCs instruction and data caches are 32KBytes each with 3 cycle latency, have a 256KByte level 2 cache with 9 cycle latency, and a 1-2MByte off-die level 3 cache with a 64-bit 250MHz connection and 40 cycle latency (quite slow), though more recent versions use up to 2MBytes of DDR SRAM effectively running at one-half the CPU clockrate (250MHz DDR = 500 MHz effective at 1 GHz).
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<strong>That would be cool, but I don't see 1GB+ (which will be standard some day) SRAM ever being affordable to mere mortals.
SRAM should have better latency than SDRAM, but I read somewhere that the SRAM used by the G4's L3 cache had a 40 cycle latency. That sounds high. I didn't think even SDRAM had such bad latency.
Am I wrong or is Apple, using the cheapest RAM they can find for their PowerMacs?</strong><hr></blockquote>
1GB of SRAM affordable? Probably not, which is why I say its in the future. Yet I still daydreamed about it back in my intro computer architecture class. Ahhh....
Find me stats on the SRAM's latency and I'll buy it. True, Apple historically skimps on RAM and overcharges, but I have no data on SRAM in Apple's history. Theoretically, the SDRAM would have a lot higher latency than any SRAM. As I recall (though it has been a while) you'd have to design SRAM pretty poorly to make it as latent as SDRAM. (This is an open invitation to anyone who ACTUALLY knows better to correct me--though politely please
quoted:
CPU caches: The G4+ PowerPCs instruction and data caches are 32KBytes each with 3 cycle latency, have a 256KByte level 2 cache with 9 cycle latency, and a 1-2MByte off-die level 3 cache with a 64-bit 250MHz connection and 40 cycle latency (quite slow), though more recent versions use up to 2MBytes of DDR SRAM effectively running at one-half the CPU clockrate (250MHz DDR = 500 MHz effective at 1 GHz).
Apple...I hate it when you're cheap...
I don't know whether the Spymac rumor is ligitiment, but if it is, I'll be very disappointed. Is 1.2GHz really the best Motorola can do?
5 months and only 200MHz increase?