ALFA 20DX manual Parallel Interface Pin Assignments, Ecp

Parallel Interface Pin Assignments

Pin No.	Signal Name	Signal Direction	Compatible	Nibble	ECP	Functions
1	Data Strobe	To printer	nStrobe	Host Clk	Host Clk	Parallel data sampling strobe
2-8	Data Bit n	To printer	Data n (LSB)	Data n (LSB)	Data n (LSB)	Parallel input data
9	Data Bit 8	To printer	Data 8 (MSB)	Data 8 (MSB)	Data 8 (MSB)	Parallel input data
10	Acknowledge	From printer	nAck	PtrClk	PeriphClk	Completion of data input or end of
						functioning
11	Busy	From printer	Busy	PtrBusy	PeriphAck	During print processing or during alarm
12	Paper End	From printer	PError	AckDataReq	nAckReverse	End of paper
13	Select	From printer	Select	Xflag	Xflag	Select state (on-line)
14	Auto Feed	To printer	nAutoFd	HostBusy	HostAck	Request to change mode
15	-	-	-	-	-	(not used)
16	0V	-	Logic Gnd	Logic Gnd	Logic Gnd	Signal ground
17	Chassis Ground	-	Chassis Gnd	Chassis Gnd	Chassis Gnd	Chassis ground
18	+5V	From printer	Peripheral Logic High	Peripheral Logic High	Peripheral Logic High	50 mA max.
19	0V	-	Signal Ground (nStrobe)	Signal Ground (nStrobe)	Signal Ground (nStrobe)	Signal ground
20 to 27	0V	-	Signal Ground (Data 1-8)	(Data 1-8)	(Data 1-8)	Signal ground
28	0V	-	Signal Ground (PError,	Signal Ground (PError,	Signal Ground (PError,	Signal ground
			Select, nAck)	Select, nAck)	Select, nAck)
29	0V	-	Signal Ground (Busy, nFault)	Signal Ground (Busy, nFault)	Signal Ground (Busy, nFault)	Signal ground
30	0V	-	Signal Ground (nAutoFd,	Signal Ground (nAutoFd,	Signal Ground (nAutoFd,	Signal ground
			nSelectln, nlnit)	nSelectln, nlnit)	nSelectln, nlnit)
31	Input PRIME	To printer	nlnit	nlnit	nReverseReq	Initializing signal
32	Fault	From printer	nFault	nDataAvail	nPerophReq	Paper out or during alarm
33	0V	-	-	-	-	Signal ground
34	-	-	-	-	-	-
35	-	From printer	-	-	-	Fix at Logic "1"
36	Select In	To printer	nSelectIn	1284 Active	1284 Active	Request to change Mode

E–10 Chapter 1: Setting Up