Rebooting the PC using JMP
Alex May
Thanks for reading this message. I am new
to Assembly and have only been using it for
a few weeks now.
My question is, how do I reboot the computer
using JMP in MASM. I have tried to JMP to 0ffff:0 in
an attempt, but MASM doesn't like the '0ffff' and
says something along the lines of 'non-digit number'.
Any ideas??
Thanks in advance.
Alex
Frédéric
> My question is, how do I reboot the computer
> using JMP in MASM. I have tried to JMP to 0ffff:0 in
> an attempt, but MASM doesn't like the '0ffff' and
> says something along the lines of 'non-digit number'.
Have you tried 0fffh:0?
--
Please do not reply by email
My address: f...@rz-online.de
Jim Morrison
PUBLIC _reboot
_reboot PROC FAR
MOV AX, 0F000h ; Address the BIOS re-IPL
PUSH AX
MOV AX, 0FFF0h
PUSH AX
CLI ; Shut off interrupts
RETF ; Boot
_reboot endp
James E. Morrison
astr...@i84.net
astrolabe web pages at: http://myhouse.com/mc/planet/astrodir/astrolab.htm
Alex May wrote in message <76lbq3$990$8...@winter.news.rcn.net>...
>Hi,
>
> Thanks for reading this message. I am new
>to Assembly and have only been using it for
>a few weeks now.
>
> My question is, how do I reboot the computer
>using JMP in MASM. I have tried to JMP to 0ffff:0 in
>an attempt, but MASM doesn't like the '0ffff' and
>says something along the lines of 'non-digit number'.
>
Martin Beck
>
> Hi,
>
> Thanks for reading this message. I am new
> to Assembly and have only been using it for
> a few weeks now.
>
> My question is, how do I reboot the computer
> using JMP in MASM. I have tried to JMP to 0ffff:0 in
> an attempt, but MASM doesn't like the '0ffff' and
> says something along the lines of 'non-digit number'.
>
> Any ideas??
>
> Thanks in advance.
>
> Alex
>
> al...@mayfamily.demon.co.uk
I don't know MASM really, but first you should set an 'h' behind,
also I think one should use JMP FAR, but I don't know this.
So: JMP FAR 0ffffh:0
hth
Martin
--
E-Mail: Spi...@t-online.de
ICQ : 16102775
Dupe that floppy -- Spread the wealth and copy (Joe Koss)
Quad
Quad
TBD
>
> PUBLIC _reboot
>_reboot PROC FAR
>
> MOV AX, 0F000h ; Address the BIOS re-IPL
> PUSH AX
> MOV AX, 0FFF0h
> PUSH AX
> CLI ; Shut off interrupts
> RETF ; Boot
>
>_reboot endp
Or if you're a size freak:
push -1
push 0
retf
or
mov ax, -1
push ax
dec ax
push ax
or
DB 0EAh, 0, 0, 0FFh, 0FFh
Its me !!!
On 2 Jan 1999, Jim Morrison wrote:
> Here's how I do it:
>
> PUBLIC _reboot
> _reboot PROC FAR
>
> MOV AX, 0F000h ; Address the BIOS re-IPL
> PUSH AX
> MOV AX, 0FFF0h
> PUSH AX
> CLI ; Shut off interrupts
> RETF ; Boot
>
> _reboot endp
>
>
Simplier !
Reboot proc
db 0Eah
dw 0
dw 0FFFFh
Reboot endp
or same
Reboot2 proc
cli
db 0Eah
dw 0FFF0h
dw 0F000h
Reboot2 endp
SIowTalker
enter this JMP instruction:
JMP FFFF:0000
load the CX register with 5, name it to reboot.com with this command:
nREBOOT.COM
then type W.
voila! A 5 byte program that reboots your computer. Nothing gets better than
that =)
-Slow Talker-
Michael Tippach
<siowt...@aol.com> writes
<binary>\DT</binary> is just 3 bytes for a .com file and about equally
as reliable ;-P
No JMP involved though...
Regards,
Michael Tippach
Benjamin Hauser
Hi everybody, why don愒 you use this simple code for rebooting the computer
instead of all the complicated ones shown above?
bits 16
org 100h
int 19h
NASM makes a 2-byte-com file out of it, which reboots the computer
perfectly....so what are you guys talking about in this thread?
Maybe this is a stupid question, but I惴 very new to assembler (I just wrote
2 little proggys). So please don愒 flame me...hehe....actually it would be
very nice if someone explained me the use of the other sources.......!
Thanx and bye,
-Benjamin.
Michael Tippach schrieb in Nachricht <77atla$2ep$1...@winter.news.rcn.net>...
Michael Tippach
<Benjami...@gmx.net> writes
>"This time I really gotta ask...!"
>
>instead of all the complicated ones shown above?
>
>bits 16
>org 100h
>int 19h
>
>
>NASM makes a 2-byte-com file out of it, which reboots the computer
>perfectly....so what are you guys talking about in this thread?
>
>2 little proggys). So please don“t flame me...hehe....actually it would be
>very nice if someone explained me the use of the other sources.......!
No, you're perfectly right. INT 19 does just REBOOT, IOW it causes the
boot sector of whatever the boot device may be to be loaded into RAM and
do whatever it thinks it should do.
In most cases, however, this is not what you want as hooked interrupt
vectors, for instance, will then point into nowhere, basically (INT 19
does not re-initialize the IVT or anything the like, it just reloads the
boot sector).
So, literally, re_booting_ a PC, you are right in as far as INT 19 is
the shortest way of doing so.
Nevertheless, literally spoken, what you want to do most of the time is
_restarting_ the PC instead of simply _rebooting_ it. That's where INT19
fails most of the time, unless it's beeing converted into a reset by a
driver/ memory manager etc. anyway.
BTW, my post regarding the subject was just a joke in response to that
"5 bytes is the minimum" - claim. What it realy does is causing a triple
fault which normally would be detected by the chip set and be converted
into a reset if, and only if the CPU is in real mode:
pop sp ; sp = 0 for a COM file
inc sp ; sp = 1
push sp ; can't cross a 0 boundary -> stack fault
; -> can't push -> double fault
; -> can't push -> triple fault
Again, this was just a joke and the practical use of that kind of thing
is very limited nowadays where it's better to look into things like
ExitWindowsEx() instead.
Regards,
Michael Tippach
Benjamin Hauser
BTW, nice joke! :)
CU,
-Benjamin.
Michael Tippach schrieb in Nachricht <77gs54$2pu$1...@winter.news.rcn.net>...
>No, you're perfectly right. INT 19 does just REBOOT, IOW it causes the
>boot sector of whatever the boot device may be to be loaded into RAM and
>do whatever it thinks it should do.
>
(...)
>
>
>Regards,
>
>Michael Tippach
Richard Day
> "This time I really gotta ask...!"
>
> Hi everybody, why don“t you use this simple code for rebooting the computer
> instead of all the complicated ones shown above?
>
> bits 16
> org 100h
> int 19h
>
> NASM makes a 2-byte-com file out of it, which reboots the computer
> perfectly....so what are you guys talking about in this thread?
>
> Maybe this is a stupid question, but I“m very new to assembler (I just wrote
> 2 little proggys). So please don“t flame me...hehe....actually it would be
> very nice if someone explained me the use of the other sources.......!
>
> Thanx and bye,
> -Benjamin.
>
> Michael Tippach schrieb in Nachricht <77atla$2ep$1...@winter.news.rcn.net>...
> >In article <777nnc$ln1$1...@winter.news.rcn.net>, SIowTalker
> ><siowt...@aol.com> writes
> >>If ya want it REALLY small, load up dubug and at the prompt type a100.
> Then
> >>enter this JMP instruction:
> >>
> >>JMP FFFF:0000
> >>
> >>load the CX register with 5, name it to reboot.com with this command:
> >>nREBOOT.COM
> >>then type W.
> >>voila! A 5 byte program that reboots your computer. Nothing gets better
> than
> >>that =)
> >
> ><binary>\DT</binary> is just 3 bytes for a .com file and about equally
> >as reliable ;-P
> >
> >No JMP involved though...
> >
> >Regards,
> >
> >Michael Tippach
> >
actually int19 doesn't work for all comps :P
and the preferred method of rebooting the pc is to use the keyboard controller
actually :)