Speed up System clock problem

mu_gua

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Jun 15, 2005, 4:11:35 AM6/15/05

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I want to change windows 2000 speed by modifying 8253 chip.
The program select channel 0(Timer tick) and mode 2 (rate
generator; generate one pulse after 'count' CLK cycles;
output remains high until after the new countdown has
begun; reloading the count mid-period does not take affect
until after the period)

Timer is set for 0x4cd * 813.8 ns = 1 ms (LSB followed by MSB)

source code like this
outp(0x43, 0x34);
outp(0x40, 0xcd); least significant byte of timer count
outp(0x40, 0x04); most significant byte of timer count

I use a driver that can opreate IO port sucessed.

But I have two problem .

1 Sometime the speed changed but after 1 or 2 second, the speed
is restored. I can see system clock run fast then slowly.
2 Sometime the speed is faster.

Maxim S. Shatskih

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Jun 15, 2005, 11:31:38 AM6/15/05

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> I want to change windows 2000 speed by modifying 8253 chip.

Bad idea. RTC clock is also used in Windows, and you do not know what of them
is the main OS clock.

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
ma...@storagecraft.com
http://www.storagecraft.com

Guillaume

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Jun 15, 2005, 11:41:59 AM6/15/05

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mu_gua wrote:
> I want to change windows 2000 speed by modifying 8253 chip.

You must be kidding.
What you need to toy with has a name: DOS.

Pavel A.

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Jun 15, 2005, 3:41:03 PM6/15/05

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"Guillaume" wrote:
> You must be kidding.
> What you need to toy with has a name: DOS.

Err... you mean, HAL ?

--PA

Tim Roberts

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Jun 16, 2005, 11:59:02 PM6/16/05

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"mu_gua" <mu_...@yahoo.com> wrote:
>
>I want to change windows 2000 speed by modifying 8253 chip.

Umm, do you understand that this doesn't actually make Windows run any
faster? And, in fact, by increasing the number of timer interrupts, you
will actually increase the unproductive overhead?
--
- Tim Roberts, ti...@probo.com
Providenza & Boekelheide, Inc

Arkady Frenkel

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Jun 17, 2005, 8:30:49 AM6/17/05

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That real started in old dos times and went to hal from NT
BTW timer.c in Platform Builder of Windows CE show how that done there (
timer interval set to 1 ms ) , but all sources there built/ checked with
that in mind so how big ( desktop ) windows will behave in this case is
absolutely unpredictable.
Arkady

"Pavel A." <pav...@NOwritemeNO.com> wrote in message
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Arkady Frenkel

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Jun 17, 2005, 8:53:01 AM6/17/05

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BTW VenturCom (Ardence now ) in their RTX or Tenasys in RMX do that
changing timer to 1 msec but control to Windows they return in 10 msec ( if
no tasks running in those RT oses )
Arkady

"Arkady Frenkel" <ark...@hotmailxdotx.com> wrote in message
news:ud$dDBzcF...@TK2MSFTNGP15.phx.gbl...

Pavel A.

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Jun 19, 2005, 10:23:02 AM6/19/05

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"Arkady Frenkel" wrote:
> BTW VenturCom (Ardence now ) in their RTX or Tenasys in RMX do that
> changing timer to 1 msec but control to Windows they return in 10 msec ( if
> no tasks running in those RT oses )
> Arkady

They do this with a custom HAL, right? or just call ExSetTimerResolution?

Regarding "big Windows": there are several sources of the system clock tick,
that the HAL can chose on startup, depending on present hardware and HAL type
(UP, MP, APIC): the "int 0" timer, "int 8" timer, APIC timer. Maybe some
future Windows will support HPET.
The timer source determines the minimal granularity of system tick: 1 or 2 ms.
AFAIK, how exactly HAL selects the source is not documented anywhere :(

--PA