isabel@june.cs.washington.edu (Isabel Domenech) (07/16/88)
My Taiwanese AT compatible has started to give me occasionally the following
message on power-up:
No timer tick interrupt
The problem seems to manifest itself only when the machine is really cold;
after it warms up for a while I am able to reboot without getting the message
and everything is OK.
While the problem is present the machine works but very sluggishly, with
erratic delays. It may also hang up.
From all this I assume a bad chip in the machine, something that I assume I
could replace myself and save money but I do not know which chip is
responsible for the timer tick.
If anybody can help me locate the proper IC on my motherboard I will be
grateful. Thanks.
Isabel Domenech (isabel@june.washington.edu)isabel@june.cs.washington.edu (Isabel Domenech) (07/16/88)
The e-mail address I put on the referenced article is not right. The correct
one is
isabel@june.cs.washington.edu
My apologies.johnson@c10sd1.StPaul.NCR.COM (Wayne D. T. Johnson) (07/19/88)
In article <5293@june.cs.washington.edu> isabel@june.cs.washington.edu (Isabel Domenech) writes: > >My Taiwanese AT compatible has started to give me occasionally the following >message on power-up: > No timer tick interrupt > >The problem seems to manifest itself only when the machine is really cold; >after it warms up for a while I am able to reboot without getting the message >and everything is OK. > >While the problem is present the machine works but very sluggishly, with >erratic delays. It may also hang up. > >From all this I assume a bad chip in the machine, something that I assume I >could replace myself and save money but I do not know which chip is >responsible for the timer tick. > >If anybody can help me locate the proper IC on my motherboard I will be >grateful. Thanks. > >Isabel Domenech (isabel@june.washington.edu) The timer tick is generated originally by a 8284 Clock Generator chip, this takes the 14.318 (or whatever you have) crystal and generates the systems clock. (In my NCR PC-8 this is a separate crystal than the system clock.) This is then fed to a 8254 chip that divides the signal by a software value. The 8254 generates an interrupt after every 65536 clock pulses thus generating your clock tick 18.2065 times per second. When you say your system sluggishly, this could be because your system clock is not operating properly. You may want to try and replace your crystal first and then the 8284 Clock chip. WARNING: The inside of your PC is static sensitive and you should only go poking (or sodering) around with an appropriate ground strap for both you and your sodering iron. I must disclaim this information... This is how my (and most other systems I know of) work, your best bet would be to get a schematic for your machine and/or take it to a qualified tech. -- Wayne Johnson (Voice) 612-638-7665 NCR Comten, Inc. (E-MAIL) W.Johnson@StPaul.NCR.COM or Roseville MN 55113 johnson@c10sd1.StPaul.NCR.COM These opinions (or spelling) do not necessarily reflect those of NCR Comten.