DEFINITION MODULE GlassTTY;

	(********************************************************)
	(*							*)
	(*	     Simple screen output routines.		*)
	(*							*)
	(*  This module handles screen output at a very low	*)
	(*  level, without supplying the advanced features	*)
	(*  which may be found in, for example, module Windows.	*)
	(*  It is intended for things like error message	*)
	(*  output, and is designed for compactness rather	*)
	(*  than comprehensiveness.				*)
	(*							*)
	(*  Programmer:		P. Moylan			*)
	(*  Last edited:	13 December 1993		*)
	(*  Status:		OK				*)
	(*							*)
	(********************************************************)

FROM SYSTEM IMPORT
    (* type *)	BYTE, ADDRESS;

PROCEDURE WriteChar (ch: CHAR);

    (* Writes one character. *)

PROCEDURE WriteString (text: ARRAY OF CHAR);

    (* Writes a string of characters.	*)

PROCEDURE WriteLn;

    (* Moves the screen cursor to the beginning of the next line,	*)
    (* scrolling if necessary.						*)

PROCEDURE SetCursor (row, column: CARDINAL);

    (* Moves the screen cursor to the specified row and column.		*)

PROCEDURE SaveCursor;

    (* Remembers the current cursor position, for use by a subsequent	*)
    (* call to RestoreCursor.  Note that nesting is not supported, i.e.	*)
    (* a call to SaveCursor destroys the information saved by any	*)
    (* earlier call to SaveCursor.					*)

PROCEDURE RestoreCursor;

    (* Sets the cursor back to where it was at the time of the last	*)
    (* call to SaveCursor.						*)

PROCEDURE WriteHexByte (number: BYTE);

    (* Writes its argument as a two-digit hexadecimal number.		*)

PROCEDURE WriteHexWord (number: CARDINAL);

    (* Writes its argument as a four-digit hexadecimal number.		*)

PROCEDURE WriteInt (number: INTEGER);
PROCEDURE WriteCard (number: CARDINAL);
PROCEDURE WriteLongCard (number: LONGCARD);

    (* Writes a number to the screen.	*)

PROCEDURE WriteAddress (addr: ADDRESS);

    (* Writes a segmented address to the screen.	*)

END GlassTTY.