From: osoelgaultier+@CMU.EDU (Stefan Monnier)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Mhz questions advanced
Date: 8 Oct 92 23:12:06 GMT
Article-I.D.: andrew.EepH36i00VpQ00wWss
Organization: Junior, Math/Computer Science, Carnegie Mellon, Pittsburgh, PA

Excerpts from netnews.comp.sys.ibm.pc.hardware: 8-Oct-92 Mhz questions
advanced Gianluca Fini@nyx.cs.du. (2737)


> Newsgroups: comp.sys.ibm.pc.hardware
> Subject: Mhz questions
> Summary: Mhz questions advanced
> Keywords: PC

> I have some question about PC's motherboards. If there's someone out there that
> can answer to one or more of them...thanks in advance!

> 1. I have a Simphony board 486 50Mhz. My AMI Bios is dated 01-20-92. In
> advanced
>  CMOS setup I can find two 'strange voices': internal cache (enabled disabled)
>  external cache (present absent). Originally Internal cache was enabled
> and exter
>  nal was absent. I have 256Kbyte cache TOSHIBA at 20 ns... But the normal RAM
>  is 80 ns... When I enabled external cache I obtained that the string
> "256K cache"
>  is shown at boot and the PC is a little bit (only a little in RAM test)
> faster.
>  What does they mean..enabling/disabling 256Kcache should be much more incisive
>  and I foud it is incisive enabling/disabling Internal cache setting...what
>  is that..I do not think that is is possible to disable internal 486's
> 8K cache!

Sure, 8K internal cache can be disabled (and has even much more configuring
possibilities). Whether the RAM test uses big chunks of memory of small
ones can significantly change the result: the cache may do all the work,
resulting in very high speed, or the cache may be too small. The only
interesting test is a real application !

> 2. I set 0wait states in BIOS setup. It works fine. So it should mean
> that changing
>  my 80ns RAM with 60ns should NOT improve PC speed (256K cache should
> ammortize  slow RAM...)

True, it shouldn't !

> 3. I set BUS CLOCK division (voice: ATCLK2/x where x is 2 2.5 3 4 5 6) to be
>  divided by 2!!!!! So my ISA bus runs at 25Mhz??? Is it possible.
>  Using other BUS divisions my PC slows down significantly (HD trasfer
> rate above all)

There are a lot of clocks in your PC. ATCLK2 is unlikely to run at 50Mhz, 
but rather at 25Mhz. So that you bus runs at 12.5 Mhz: fast but possible !
(just notice that divide by 2.5 is not trivial to do, whereas divide by 5 is.
Your ATCLK2/2.5 is likely to be in fact 50Mhz/5

> 4. How can I calculate the trasfer rate of my HD?? Core test gives me
>   the value of 1.4Mbytes, Norton sysinfo 990Kbytes, CP SI 890Kbytes!!!
>   I made the tests with no AUTOEXEC.BAT and CONFIG.sys (nothig resident no
>  software or Hardware cache). I own a Western Digital Pirana(212Mb).

Just like RAM test: the result is really test dependant. Never compare between
different tests but between different configurations with one test.

> 5. I would like to exchange benchmarks info with You all. You can rename
>   Your AUTOEXEC.BAT and CONFIG.SYS, reboot and run all tests of PCLABS BENCH
>   5.0 or 6.0. Then print the file and e-mail it to me at

>  tbra380@cdc835.cdc.polimi.it

>   I'll collect all and I could send back the entire collection to people who
>   sent me one BENCH.
>   Remember to eliminate autoexec.bat end config.sys!!!
>   Also Windows tests (WinBench) are accepted. In this case tell me Your
> configuration
>  (sende me also config, autoexec, win.ini, system.ini).
>   You shoul also tell me what You know about Your hardware configuration.

> 6. This one is difficult: I heard about 80ns RAM working at the same speed of 6


>   RAM because of the major quality of the RAM...someone told me that
>   an 80ns RAM TOSHIBA or SGS is better than a 60ns RAM xxxxx(unknown name)
>   Is it true????? Have You experience on this????

No idea !

> 7. The last: in 66Mhz DX2 PCs the cache RAM works at 66 or 33 Mhz?? And
> the normal
>   RAM

internal cache RAM works at 66Mhz, all the external part works at 33
(or anything else, depending on the board)

> Sorry for the errors but the terminal was so slow...
> Thank in advance
>   tbra380@cdc835.cdc.polimi.it


	Stefan

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