Re: A85: Interrupt/Usgard-TSR question

To: assembly-85@lists.ticalc.org
Subject: Re: A85: Interrupt/Usgard-TSR question
From: "Richard Gallagher" <rbg@cvm.co.nz>
Date: Mon, 27 Oct 1997 01:42:40 +1200
Comments: Authenticated sender is <rwg1@wave.co.nz>
In-reply-to: <3452ba5b.187832681@mail.anet-dfw.com>
References: <19971025.232138.9630.0.egillespie@juno.com>
Reply-To: assembly-85@lists.ticalc.org

> No, that is correct, anyone who has made a clock-like timer know this.
> Are you sure it is that slow on the PC?  i didn't think that there was
> a fixed time between interrupts on PC's like there is on the calc.
> 
> -mike

The your typical PC has an Intel 8253 or 8254 or compatible 
Programmable Interval Timer.  It has 3 channels, one channel for 
generating an interrupt for the system clock, one channel for 
generating a signal for DRAM refreshing and the third channel for the 
in built speaker.  The second channel is not used at all in modern 
machines, other hardware takes care of it.

The first channel generates hardware interrupt number 8.  On start up 
the bios sets it at 18.2Hz.  However it can be reprogrammed to 
generate a signal at frequencies between 18.2Hz and 1.2Mhz.

--
Richard Gallagher
rbg@cvm.co.nz
http://www.cs.waikato.ac.nz/~rbg/

References:

Re: A85: Interrupt/Usgard-TSR question

From: egillespie@juno.com (Erik L Gillespie)

Re: A85: Interrupt/Usgard-TSR question

From: mikep@anet-dfw.com (Michael Pearce)