45 pin Apple HDI-45 connector at the Apple computer, looking into cable-side connector.
The Apple AudioVision 14 Display (1993) connects to the first-generation Power Macintosh computers — the 6100, 7100, and 8100 — via a proprietary 45-pin High-Density Interconnect connector known as the HDI-45. Apple marketed the associated cable as the Integrated Desktop Cable (IDC) because it consolidated analogue RGB video output, stereo audio input and output, an Apple Desktop Bus (ADB) pass-through, and S-Video input into a single locking connector. The HDI-45 was used exclusively on those three Power Macintosh models and their matching display; no other Apple product adopted it, and an adapter was required to use the machines with standard DA-15 monitors.
| Pin | Name |
|---|---|
| 1 | Analog audio ground |
| 2 | Audio input shield |
| 3 | Left channel audio input |
| 4 | Right channel audio input |
| 5 | Left channel audio output |
| 6 | Right channel audio output |
| 7 | Reserved |
| 8 | Monitor ID sense line 1 |
| 9 | Monitor ID sense line 2 |
| 10 | Green ground (shield) |
| 11 | Green video output (75 ) |
| 12 | Video input power ground |
| 13 | Power for camera +5 V |
| 14 | Reserved |
| 15 | Reserved |
| 16 | Reserved |
| 17 | Reserved |
| 18 | Monitor ID sense line 3 |
| 19 | S-video input shield |
| 20 | S-video input luminance (Y) |
| 21 | S-video input chroma (C) |
| 22 | Reserved |
| 24 | Reserved |
| 25 | Reserved |
| 26 | Red ground (shield) |
| 27 | Red video output (75 ) |
| 28 | I2C data signal |
| 29 | I2C clock signal |
| 30 | Reserved |
| 31 | Monitor ID |
| 32 | Monitor ID |
| 33 | Vertical sync signal |
| 34 | Composite sync signal |
| 35 | ADB power +5 V |
| 36 | ADB ground |
| 37 | ADB data |
| 38 | Keyboard switch |
| 39 | Reserved |
| 40 | Reserved |
| 41 | Monitor ID |
| 42 | Horizontal sync signal |
| 43 | Video sync ground |
| 44 | Blue ground (shield) |
| 45 | Blue video output (75 ) |
Notes
The HDI-45 is a locking, high-density 45-pin D-type connector unique to Apple. It is not compatible with the standard DA-15 analogue video connector found on the LC, IIci, Quadra, and most other desktop Macintosh models from the same era. The Power Macintosh 6100, 7100, and 8100 each have one HDI-45 port on the rear panel; an Apple-supplied adapter breaks the connector out to a DA-15 video port, standard 3.5 mm audio jacks, and an ADB connector for use with conventional monitors and peripherals. Video output is analogue RGB at 75 Ω impedance on the red (pin 27), green (pin 11), and blue (pin 45) lines, with separate horizontal sync (pin 42), vertical sync (pin 33), and composite sync (pin 34) signals. The ADB section (pins 35–37) follows the standard ADB electrical specification, allowing a keyboard or mouse to be chained through the display. Three monitor-ID sense lines (pins 8, 9, 18) and an additional monitor-ID pin (pins 31, 32, 41) allow the machine to identify the connected display using the same sense-code scheme as the DA-15 connector. The S-Video input path (pins 20–21 for Y/C luminance and chroma) includes a shield line (pin 19) and uses I²C for control (pins 28–29). Pin 23 is absent from the table as manufactured (the connector body skips that position).
Signals
- Analog audio ground — common ground reference for all audio circuits
- Audio input shield — coaxial shield for the audio input pair
- Left channel audio input — line-level left-channel audio signal from external source to Mac
- Right channel audio input — line-level right-channel audio signal from external source to Mac
- Left channel audio output — line-level left-channel audio signal from Mac to display speakers
- Right channel audio output — line-level right-channel audio signal from Mac to display speakers
- Reserved — not connected; reserved by Apple for future use
- Monitor ID sense line 1 — sense line for display identification (part of HDI-45 monitor-ID scheme)
- Monitor ID sense line 2 — sense line for display identification
- Green ground (shield) — coaxial shield / ground for the green video signal
- Green video output (75 Ω) — analogue green component of RGB video, 75 Ω terminated
- Video input power ground — ground reference for the video input section
- Power for camera +5 V — +5 V supply to power an optional camera or video-input accessory
- Reserved — not connected; reserved by Apple
- Monitor ID sense line 3 — third sense line for display identification
- S-video input shield — coaxial shield for the S-Video input pair
- S-video input luminance (Y) — luminance component of S-Video input signal
- S-video input chroma (C) — chrominance component of S-Video input signal
- Red ground (shield) — coaxial shield / ground for the red video signal
- Red video output (75 Ω) — analogue red component of RGB video, 75 Ω terminated
- I²C data signal — I²C serial data line for display control and identification
- I²C clock signal — I²C serial clock line for display control and identification
- Monitor ID — additional monitor identification line (pin 31)
- Monitor ID — additional monitor identification line (pin 32)
- Vertical sync signal — vertical synchronisation pulse for the video signal
- Composite sync signal — combined horizontal and vertical sync pulse
- ADB power +5 V — +5 V supply on the Apple Desktop Bus branch
- ADB ground — ground reference for the ADB branch
- ADB data — bidirectional Apple Desktop Bus data line (keyboards, mice, etc.)
- Keyboard switch — detects whether a keyboard is connected to the display’s ADB port
- Monitor ID — additional monitor identification line (pin 41)
- Horizontal sync signal — horizontal synchronisation pulse for the video signal
- Video sync ground — ground reference for the sync signal lines
- Blue ground (shield) — coaxial shield / ground for the blue video signal
- Blue video output (75 Ω) — analogue blue component of RGB video, 75 Ω terminated