Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!samsung!rex!uflorida!haven!adm!news
From: nobody@kodak.com (Thomas Bullinger, KAG, Tel.: (049-))
Newsgroups: comp.lang.pascal
Subject: RE:      INT 019h question
Message-ID: <25210@adm.brl.mil>
Date: 7 Dec 90 07:18:40 GMT
Sender: news@adm.brl.mil
Lines: 40


Hi Tom,
In your article you wrote:

>Now I'm really comfused!  So,  I look in my handy _Mastering_Turbo_Assembler_
>by Tom Swan:  Sure enough there's a rebooting module.  The code uses the
>BIOSData segment to load the 1234h and then uses a JMP FAR to the reboot
>code!!!
>
>Here's my question:  WHY?!?!?!?  Why wont int19h do as written?  I have
>already written the short ( 585 byte ) exe file for them, but I'm still
>confussed as to why it was done this way.  Any ideas are welcomed.  Respond
>tom me or any of these lists as I read them all.
>
>Thanks,
>
>tom

I tried it once the way you did. After failing I looked into some magazines
etc. to look for it:
As far as I know, the INT 19H tries to boot the PC. If it fails, it will
switch to the built-in BASIC. In clones there is none, so it hangs.

So I wrote a tiny little program to reboot the PC and called it BOOT.COM:

	MOV	AX,40H		;Select BIOS Area
	MOV	ES,AX
	MOV	ES:[72H],1234H	;Bypass memory test
				;Set to 0000H to perform memory tests too
	JMP	0FFFF:0000H	;Reboot

This code always works, on PC's, on clones and even on PS/2.

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| Thomas Bullinger | bulli@kodak.com           |
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