Subject: Re: VIA VP2 chipset
To: None <current-users@NetBSD.ORG, port-i386@NetBSD.ORG>
From: David Jones <firstname.lastname@example.org>
Date: 02/01/1998 20:59:28
Greg A. Woods wrote:
| If I can find ECC SDRAM DIMMs (though I have not yet even found a
| manufacturer that makes them yet), I'll use them, but at the moment it
| seems 64MB (x72bit) EDO DIMMs are the best you can find, at least hear
| on the open market in Toronto. If anyone has any comments on the
| improved memory bandwidth of SDRAM over EDO with the VP3 I'd be most
Why do you need ECC?
SDRAM DIMMs are fairly common, at least in Ottawa.
In general, SDRAM bandwidth is limited to 66 MHz, whereas EDO maxes out
at 40-50 MHz. However, the row access time (tRAC+CAS latency 3) for SDRAM
is longer, so random accesses don't perform as well. SDRAM is best for
cache controllers that can look ahead and schedule their accesses.
The Intel-100 spec is coming out. This spec clarifies CLK-to-Q delays
for SDRAMS, and will result in 100 MHz SDRAMs (current 100 MHz SDRAMs
don't have a good enough CLK-to-Q delay, so they are run at only 66 MHz.)
So you might want to wait a year.
Then again, wait two years. At that point SLDRAM will be out, with
600 MHz transfers from CPU to memory.