GNU/Linux 2.6, Slackware 12.0
apmsleep 1.3, revision 1.1

Hi:
I found, via 'apropos standby', the apmsleep command and I am reading the man page.
The manual (man page) speaks about the required system configuration and says:

[QUOTE]
REQUIRED SYSTEM CONFIGURATION.
Kernel: The special character device /dev/rtc must exist and the kernel
needs to be compiled with APM and RTC support.

BIOS: The computer must have the 'suspend to RAM' feature enabled in the
BIOS; 'suspend to Disk' will not work, because the computer is
turned off completely. You do not need to enable the ALARM timer,
it will be activated by apmsleep. On some boards, you can config-
ure which interrupts can be used to awake from suspend mode. If
you have such a board, you might want to make sure that keyboard
(IRQ 1) and RTC (IRQ 8) are among those interrupts. If your com-
puter does not wake up, try to enable 'modem ring' in the BIOS,
even if you do not have a modem.
[QUOTE END]

Here is what the program does:
$ apmsleep +00:05
apmsleep: Your kernel does not support APM.
apmsleep: Recompile kernel with APM and /dev/rtc support
$

I did ls -l /dev/rtc and the output was 'rtc -> misc/rtc'. So, I guess /dev/rtc exists. As to compiling with APM and RTC support, I would need some guidance. About the BIOS, I have checked the CMOS menu through and through and did not find the Suspend to RAM (or Suspend to disk, for that case) option. Mine is a Pentium Celeron desktop computer. I can say that, running other o.s. on this machine, I can put it into standby, indeed.

However, the author says he tested the program on a Winbook XL laptop (Pentium) only. Also, the manual is dated January 2004. 'apmsleep --version' gets
Version: $Revision: 1.1 $ (apmsleep 1.3).
I would greatly appreciate any suggestions.

Some pieces of information which could be useful to a
would be helper:
(a) At the time of this writing, the system puts the monitor into standby after some 30m have elapsed.
(b) Motherboard ID ends with M758LT-H.
(c) The Slackware package containing apmsleep is apmd-3.2.2-i486-1

P.S.: Maybe I should have posted this post in the hardware forum. If so, please let me know and I will try to have it moved there.

Is it possible to add APM support to the kernel by inserting some module? Thanks in advance.

I now see its very like my running kernel (2.6.21.5) already has ACPI support build into it. So, for the time being, I'll shift my attention to ACPI and will unsubscribed from the thread and mark it 'solved'. Sorry for the waste of time employed by whoever read these posts.