Function Name: SETMSG

Purpose: Kernal messages on/off
Call address: $FF90 (hex) 65424 (decimal)

	Registers:	.A = message control
	Memory:		system map
	Flags:		none
	Calls:		none
	Registers:	none
	Memory:		MSGFLG ($9D) updated
	Flags:		none

Description: SETMSG updates the Kernal message flag byte MSGFLG ($9D) that determines whether system error and/or control messages will be displayed. BASIC normally disables error messages always and disables control messages in Run mode. Note that the Kernal error messages are not the verbose ones printed by BASIC, but simply the I/O ERROR # message that you see when in the Monitor, for example. Examples of Kernal control messages are LOADING, FOUND, and PRESS PLAY ON TAPE. The MSGFLG control bits are:

MSGFLG bit 7 = 1 -> enable CONTROL messages
       bit 6 = 1 ->> enable ERROR messages


	LDA	#0
	JSR	$FF90	; turn OFF all Kernal messages