;	TITLE	"SCST - Syslib 4.0"
	NAME	('CST')
;==============================================================
; Author  : Harold F. Bower
;		derived from SCST.Z80 Ver 1.1 by Richard Conn
; Date    : 11 Jun 89
; Version : 1.3
; Module  : SCST
; Abstract: This module contains the routine CST which uses a
;	direct BIOS access to read the CON: device status for
;	character ready.
;  Revision:
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; Module Entry Points

	PUBLIC		CST

; From SYSLIB Get..

	EXT		@BIOSA

; Definitions

CS	EQU	2		; Console Status Function number

	.Z80
	CSEG
;===============================================================
; NAME - CST
; Entry: - None
; Exit :  A = 0, Zero Flag Set (Z) if Data Available
;	      A = 1, Zero Flag Clear (NZ) if NO Data Available
; Uses : AF
; Special Requirements: The system BIOS MUST start on an even
;	page boundary.
;===============================================================

CST:	LD	A,CS		; Load the BIOS Function Number
	PUSH	BC		; Save the Registers
	CALL	@BIOSA		; ..and call the function
	POP	BC		; Restore regs
	CPL			; Complement CONST return code
	AND	1		; ..masking for LSB
	RET

	END