15 pin D-SUB female connector at the videocard.
15 pin D-SUB male connector at the cable.
The DA-15 (two-row, 15-pin D-sub) external video connector was fitted to the full family of Macintosh II NuBus video cards introduced with the Macintosh II in 1987, including the Macintosh II Video Card, Display Card 4•8, Display Card 8•24, Display Card 8•24 GC, High-Resolution Video Card, Extended High-Resolution Video Card, and the original Macintosh Monochrome Video Card. All of these cards share the same DA-15 female connector and signal assignment, as documented in Chapter 12 of Apple’s Guide to the Macintosh Family Hardware (2nd edition, 1990). The available colour depth is determined by the amount of installed VRAM: 256 KB provides 4-bit colour (16 colours at 640×480), whilst 512 KB provides 8-bit colour (256 colours at 640×480); the monochrome card operates at 1-bit depth. Three monitor sense lines on the connector allow the Mac to identify the connected display and select the appropriate timing automatically, a scheme later formalised in Apple Technical Note HW30 (September 1992).
| Pin | Signal | Description |
|---|---|---|
| 1 | RED.GND | Red video ground |
| 2 | RED.VID | Analog Red video |
| 3 | CSYNC/ | Composite sync |
| 4 | SYNC.GND | Sync signal ground |
| 5 | GRN.VID | Analog Green video |
| 6 | GRN.GND | Green video ground |
| 7 | N/C | No connection |
| 8 | N/C | No connection |
| 9 | BLU.VID | Analog Blue video |
| 10 | N/C | No connection |
| 11 | N/C | No connection |
| 12 | N/C | No connection |
| 13 | BLU.GND | Blue signal ground |
| 14 | N/C | No connection |
| 15 | N/C | No connection |
| shield | Shield ground |
Notes
The connector is correctly classified as DA-15 (two rows of contacts), not DB-15 (three rows); the colloquial designation “DB-15” is widely encountered but technically incorrect. The DA-15 female socket is mounted on the video card, and the mating cable carries a DA-15 male plug. Early revisions of the Macintosh II Video Card lacked internal pull-up resistors on the monitor sense lines; later revisions and the IIci built-in video added pull-ups on sense pins 1 and 2. Technical Note HW08 specifies that pin 4 (SENSE0) must be grounded at the monitor or cable end to signal a 640×480 display to cards and systems that implement the sense scheme. The DA-15 signals on these NuBus cards are electrically incompatible with the DA-15 connector used on the Apple IIc, Apple IIGS, Apple III, and Apple EtherTalk Interface Card — physical interchangeability does not imply signal compatibility.
Signals
- RED.GND — Analogue ground reference for the red video signal
- RED.VID — Analogue red component video signal
- CSYNC/ — Composite sync (active low), combining horizontal and vertical sync
- SYNC.GND — Ground reference for composite sync and vertical sync signals
- GRN.VID — Analogue green component video signal
- GRN.GND — Analogue ground reference for the green video signal
- N/C — No connection (pins 7, 8, 10–12, 14–15 on this early card variant; later DA-15 implementations use these pins for SENSE1, SENSE2, VSYNC/, and HSYNC/ — see Technical Notes HW08 and HW30)
- BLU.VID — Analogue blue component video signal
- BLU.GND — Analogue ground reference for the blue video signal
References
- Guide to the Macintosh Family Hardware, Second Edition (1990) — Apple Computer, Inc. / Addison-Wesley; Chapter 12 covers DA-15 video connector pin assignments (Table 12-1) and monitor sense line values (Table 12-2)
- Apple Technical Note HW08: Color Monitor Connections (February 1991) — Apple Computer, Inc.; covers Macintosh II Video Card DA-15 adapter cable wiring and sense line requirements
- Apple Technical Note HW30: Sense Lines (September 1992) — Apple Computer, Inc.; defines the 3-bit and extended 6-bit monitor sense line identification scheme for DA-15 connectors