IBM DS-2000 warranty Functional Description Line Status Register, Ffrx, Temt, Thre

				FUNCTIONAL			DESCRIPTION
		F . LINE		STATUS	REGISTER
	+------		+
D7		FFRX	-----	Error	in FIFO RCVR			(FIFO only)
	+------		+
D6		TEMT	-----	Transmitter			empty
	+------		+
D5		THRE	-----	Transmitter			holding	register empty
	+------		+
D4		BI	-----	Break	interrupt
	+------		+
D3		FE	-----	Framing		error
	+------		+
D2		PE	-----	Parity		error
	+------		+
D1		OE	-----	Overrun		error
	+------		+
D0		DR	-----	Data ready
	+------		+

Figure 12. Line status register bit definitions.

FFRX -		FIFO Receiver Error:
		Always logic 0 in character mode.
FIFO	mode:
		I n d i c a t e s o n e o r m o r e p a r i t y e r r o r s , f r a m i n g
		e r r o r s , o r b r e a k i n d i c a t i o n s i n t h e r e c e i v e r
		FIFO. FFRX is reset by reading the line status
		register.
TEMT	-	Transmitter		Empty:
		Indicates		the transmitter holding register (or
		F I F O ) a n d t h e t r a n s m i t t e r s h i f t r e g i s t e r a r e
		empty and are ready to receive new data. TEMT is
		reset by writing a character to the transmitter
		holding	register.
THRE -		Transmitter Holding Register Empty:
		Indicates		the transmitter holding register (or
		F I F O ) i s e m p t y a n d i t i s r e a d y t o a c c e p t n e w
		d a t a .	T H R E i s r e s e t b y w r i t i n g d a t a t o t h e
		transmitter		holding register (or FIFO).

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