Path: utzoo!mnetor!uunet!husc6!hao!oddjob!sphinx!cjdb
From: cjdb@sphinx.uchicago.edu (Charles Blair)
Newsgroups: comp.sys.ibm.pc
Subject: I am curious: cursor
Message-ID: <3479@sphinx.uchicago.edu>
Date: 20 Feb 88 22:49:29 GMT
Organization: The University of Chicago
Lines: 31


I wrote a simple routine to blank the cursor before pushing to DOS, as
follows: 

	mov	dx,3B4h		; 6845 address register
	mov	al,10		; cursor start
	out	dx,al
	mov	dx,3B5h		; base address of 6845 control data reg.
	mov	al,00101011b	; 01 in bits 6-5 makes cursor invisible
	out	dx,al

(The original code uses symbolic names for the values.)

I notice that this sometimes results in cursor loss at the DOS prompt.
I haven't been able to isolate the circumstances, but it seems to
happen consistently with IBM monochrome boards, and inconsistently
with Hercules GB112's. Can anyone think of possible causes?

I realize it is unecessary to blank the cursor before a push, but I
like to do it for a bit of finesse--if the EXEC call can't find
command.com, or whatever else it is I'm pushing, I don't like seeing
the cursor on the screen while I'm putting out the message to that
effect.

Thanks for any replies; e-mail responses preferred.


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