Parallel Port Pin-Out

EPP was created in 1991 to permit up to 2 Mbps data transfer, and was intended primarily for non-printers.

ECP was created in 1992 to permit higher speed printer communications.

IEEE1284 was created in 1994 to combine EEP and ECP, and relies on the host to determine which standard to use.

Standard Parallel Port (SPP)			Enhanced Parallel Port (EPP)		Extended Capabilities Port (ECP)
Signal Name	Centronics (36-pin)	DB-25 (25-pin)	Signal Name	DB-25 (25-pin)	Signal Name	DB-25 (25-pin)
Strobe	1	1	Write	1	Host CLK	1
Data 0	2	2	Data 0	2	Data 0	2
Data 1	3	3	Data 1	3	Data 1	3
Data 2	4	4	Data 2	4	Data 2	4
Data 3	5	5	Data 3	5	Data 3	5
Data 4	6	6	Data 4	6	Data 4	6
Data 5	7	7	Data 5	7	Data 5	7
Data 6	8	8	Data 6	8	Data 6	8
Data 7	9	9	Data 7	9	Data 7	9
Acknowledge	10	10	Interrupt	10	Periph CLK	10
Busy	11	11	Wait	11	Periph ACK	11
Paper End	12	12	Spare	12	Ack Reverse	12
Select	13	13	Spare	13	X-Flag	13
Auto Line Feed	14	14	Data Strobe	14	Host ACK	14
Error	32	15	Spare	15	Periph Request	15
Initialize Printer	31	16	Reset	16	Reverse Request	16
Select Input	36	17	Address Strobe	17	1284 Active	17
Strobe Return	19	18	Ground	18	Ground	18
Data 0 Return	20	19	Ground	19	Ground	19
Data 1 Return	21	19	Ground	20	Ground	20
Data 2 Return	22	20	Ground	21	Ground	21
Data 3 Return	23	20	Ground	22	Ground	22
Data 4 Return	24	21	Ground	23	Ground	23
Data 5 Return	25	21	Ground	24	Ground	24
Data 6 Return	26	22	Ground	25	Ground	25
Data 7 Return	27	22
Acknowledge Return	28	24
Busy Return	29	23
Paper End Return	28	24
Select Return	28	24
Auto Line Feed Return	30	25
Error Return	29	23
Initialize Printer Return	30	25
Select Input Return	30	25
Shield	33	N/C
N/C	34	N/C
N/C	35	N/C