🚀 go-pugleaf

johns@rd.scitec.com.au (John Saunders) writes:
>Alan Smith (cs547091@lux.latrobe.edu.au) wrote:
>> I am upgrading my motherboard and am concidering getting an Octek DCA2
>> motherboard which uses 15nS DymamiCache.  Does anyone know much about
>> these?  
>The DCA2 uses what is called EDRAM (not EDORAM). EDRAM is basically a SIMM
>module where each memory chip includes a small amount of cache on the
>actual chip itself. So by using these special SIMM's the manufacturer
>saves the cost of cache controllers and cache chips. The SIMM's cost
>more than standard SIMM's and I don't think you can use standard ones
>even if you are willing to sacrifice speed.

You can use standard SIMMs. However, the performance will be appalling
as there will be no Level 2 cache. Also, combining EDRAM with normal
DRAM will slow it down too. They're aren't that different in price,
about $40-50 australian over a standard 8Mb.

>I have run Norton SI V7 on 3 486DX2-66 machine, 1 a DCA2 board, the other
>an SiS based VLB board and the third an Intel Saturn based PCI board.
>Guess what, exactly the same speed. So the DCA2 isn't making performance
>worse for this test, it just didn't make it better. I don't know how it
>would perform on different tests and I believe that Norton SI is a very
>basic test. Some motherboards with more than 16 Meg of RAM have problems
>caching anything above 16 Meg. I doubt this problem would happen with
>the DCA2 motherboard.

Norton's is pretty basic sorta test yes. EDRAM becomes useful when 
moving large pieces of memory around and for multitasking. As a single
user Windows/DOS machine it's probably not worth it. For something
to run a UNIX or WinNT on, it's very nice - eg gcc can operate quite
quickly in the "15ns" RAM environment (maximum 35ns on cache misses).

---
Tom Minchin				Phone: (06) 267 5038
Toad Hall				Fax:   (06) 267 4900
Australian National University		Email: tom@toadhall1.anu.edu.au
0200 Australia				URL: http://toadhall1.anu.edu.au/~tom
-- 
Tom Minchin				Phone: (06) 267 5038
Toad Hall				Fax:   (06) 267 4900
Australian National University		Email: tom@toadhall1.anu.edu.au
0200 Australia				URL: http://toadhall1.anu.edu.au/~tom