CompactFlash Pinout

50-pin parallel-ATA memory card interface from the CompactFlash Association.

Overview

CompactFlash uses a 50-position dual-row connector (two rows of 25 on 1.27 mm centers). It exposes a Parallel ATA / IDE bus - a 16-bit data bus, address lines, and ATA control strobes.

A CF card supports PC Card Memory, PC Card I/O, and True IDE modes; some pins change function between modes. True IDE signal names are shown (the configuration used by modern adapters).

Pinout

Pin	Name	Function	Description
1	GND	GND	Ground
2	D03	DATA	Data bus bit 3
3	D04	DATA	Data bus bit 4
4	D05	DATA	Data bus bit 5
5	D06	DATA	Data bus bit 6
6	D07	DATA	Data bus bit 7
7	-CS0	SPI	Chip select 0 (task-file registers), active low
8	A10	GND	Address bit 10 (GND in True IDE)
9	-OE / -ATA SEL	SIGNAL	True IDE mode select (tied low for IDE)
10	A09	GND	Address bit 9 (GND in True IDE)
11	A08	GND	Address bit 8 (GND in True IDE)
12	A07	GND	Address bit 7 (GND in True IDE)
13	VCC	POWER	+3.3 V or +5 V power
14	A06	GND	Address bit 6 (GND in True IDE)
15	A05	GND	Address bit 5 (GND in True IDE)
16	A04	GND	Address bit 4 (GND in True IDE)
17	A03	GND	Address bit 3 (GND in True IDE)
18	A02	SIGNAL	Address bit 2
19	A01	SIGNAL	Address bit 1
20	A00	SIGNAL	Address bit 0
21	D00	DATA	Data bus bit 0
22	D01	DATA	Data bus bit 1
23	D02	DATA	Data bus bit 2
24	-IOCS16 / WP	SPI	16-bit I/O chip select / write protect
25	-CD2	GND	Card detect 2 (tied to GND in card)
26	-CD1	GND	Card detect 1 (tied to GND in card)
27	D11	DATA	Data bus bit 11
28	D12	DATA	Data bus bit 12
29	D13	DATA	Data bus bit 13
30	D14	DATA	Data bus bit 14
31	D15	DATA	Data bus bit 15
32	-CS1	SPI	Chip select 1 (control/alt-status), active low
33	-VS1	SIGNAL	Voltage sense 1 (tied low by card)
34	-IORD	SIGNAL	I/O read strobe, active low
35	-IOWR	SIGNAL	I/O write strobe, active low
36	-WE	SIGNAL	Write enable, active low
37	RDY/-BSY / INTRQ	SIGNAL	Ready-busy / interrupt request
38	VCC	POWER	+3.3 V or +5 V power
39	-CSEL	SIGNAL	Cable/card select (master/slave)
40	-VS2	SIGNAL	Voltage sense 2
41	-RESET	SIGNAL	Reset, active low
42	IORDY	SIGNAL	I/O ready (wait state) signal
43	-INPACK / DMARQ	SIGNAL	Input acknowledge / DMA request
44	-REG / -DMACK	SIGNAL	Attribute register select / DMA acknowledge
45	BVD2 / -DASP	SIGNAL	Battery voltage detect 2 / drive active-slave present
46	BVD1 / -PDIAG	SIGNAL	Battery voltage detect 1 / passed diagnostics
47	D08	DATA	Data bus bit 8
48	D09	DATA	Data bus bit 9
49	D10	DATA	Data bus bit 10
50	GND	GND	Ground

Notes

Signal names shown are True IDE mode; address pins 8-17 are grounded in True IDE.
Data bus D08-D10 sit at pins 47-49, not contiguous with D11-D15.

Reference: CompactFlash Association specification; CF pinout· verified 2026-06-27