Power Macintosh 7200, 7500, 8500, 9500 Mac II Analog (35 KHz H, 66.67 Hz V - 640x480) Mac II and Quadra Analog (49.7 KHz H, 74.55 Hz V - 832x624)
15 pin D-SUB female connector at the computer.
15 pin D-SUB male connector at the video cable.
The Apple Macintosh external video connector is a DA-15 (two-row, 15-pin D-type) port used on desktop Macintosh computers from the Macintosh II (1987) through the beige Power Mac G3 (1998). It carries separate analogue red, green, and blue video signals, composite sync (/CSYNC), independent horizontal and vertical sync, and three monitor-sense lines (SENSE0, SENSE1, SENSE2) that allow the computer to automatically identify the connected display. The sense lines are read against monitor ground on pin 11: each pin is either pulled to ground by the monitor or cable (binary 0) or left floating (binary 1), forming a 3-bit code that selects the appropriate video timing. When all three sense lines read high (111), an extended dynamic polling protocol (Technical Note HW30, 1992) yields a 6-bit identification code supporting multi-scan monitors used with Quadra, Centris, and Power Macintosh systems.
| Pin | Signal | Description |
|---|---|---|
| 1 | RED.GND | Red video ground |
| 2 | RED.VID | Red video signal |
| 3 | /CSYNC | Composite synchronization signal |
| 4 | SENSE0 | Monitor sense signal 0 |
| 5 | GRN.VID | Green video signal |
| 6 | GRN.GND | Green video ground |
| 7 | SENSE1 | Monitor sense signal 1 |
| 8 | NC | No connection |
| 9 | BLU.VID | Blue video signal |
| 10 | SENSE2 | Monitor sense signal 2 |
| 11 | GND | CSYNC and VSYNC ground |
| 12 | /VSYNC | Vertical synchronization signal |
| 13 | BLU.GND | Blue video ground |
| 14 | HSYNC.GND | HSYNC ground |
| 15 | /HSYNC | Horizontal synchronization signal |
| Shell | SGND | Shield ground |
Signals
- RED.VID / GRN.VID / BLU.VID — Analogue red, green, and blue video signals on pins 2, 5, and 9 respectively; each has a dedicated ground return (pins 1, 6, 13).
- /CSYNC — Composite synchronisation signal (pin 3), combining horizontal and vertical timing; used by monitors that do not accept separate sync lines.
- /VSYNC — Vertical synchronisation signal (pin 12); ground reference is pin 11.
- /HSYNC — Horizontal synchronisation signal (pin 15); ground reference is pin 14.
- SENSE0 / SENSE1 / SENSE2 — Monitor identification sense lines on pins 4, 7, and 10 respectively, measured against monitor ground (pin 11). Each line is either grounded by the monitor or cable (binary 0) or left floating (binary 1). The resulting 3-bit code identifies the monitor type and preferred video timing. All-high (111) triggers the Extended Type-7 dynamic polling protocol, which asserts each sense line in turn and reads the other two, yielding a 6-bit code for multi-scan monitors. The Extended Type-6 scheme permanently grounds SENSE0 (pin 4) and uses the remaining two lines with jumpers or diodes to identify multi-scan monitor families.
- NC — Pin 8 carries no signal and is not connected.
- SGND — The connector shell is tied to chassis ground.
Notes
- Direction is computer relative to monitor.
- The connector is correctly designated DA-15 (two rows, 15 pins), not DB-15 (which has three rows); the term “DB-15” is widely used colloquially but is technically incorrect.
- This connector is present on the Macintosh LC, LC II/Performa 400, IIci, IIsi, Quadra 700/900/950, Duo Dock, Duo MiniDock, and Power Macintosh 7200/7500/8500/9500, among others.
- The DA-15 signals on Macintosh video cards are not compatible with the DA-15 connector on the Apple IIc, Apple IIGS, Apple III, or EtherTalk Interface Card, despite sharing the same physical shell.
- The Macintosh Portable (1989) uses a physically similar 15-pin high-density D-type connector but carries a parallel flat-panel display data bus (FPDATA[0–7], FSYNC, FCLK) — it is electrically incompatible with this DA-15 video port.
- Early revisions of the Macintosh II Video Card lacked SENSE0/1/2; later revisions added pull-up resistors on pins 7 and 10. Technical Note HW08 specifies that pin 4 (SENSE0) must be grounded for correct 640×480 monitor detection on these later cards and on the IIci built-in video.
References
- Guide to the Macintosh Family Hardware, Second Edition (1990) — Apple Computer, Inc. / Addison-Wesley; Chapter 12 Tables 12-1 and 12-2 cover the DA-15 pin assignments and monitor sense codes.
- Apple Technical Note HW30: Sense Lines (September 1, 1992) — Apple Computer, Inc.; defines the 3-bit and extended 6-bit monitor identification protocols.
- Apple Technical Note HW08: Color Monitor Connections (February 1, 1991) — Apple Computer, Inc.; DA-15 pin tables and adapter cable wiring for Sony, NEC MultiSync, and VGA monitors.
- Apple Ports and Pinouts (Service Source K reference) — Apple Computer, Inc. (archived); complete DA-15 signal list and compatibility cautions.