9 PIN D-SUB FEMALE at the Computer.
The Commodore 128’s 80-column video output is a 9-pin D-Sub female connector on the rear of the computer, carrying digital TTL RGBI signals compatible with IBM CGA-class monitors. Introduced in 1985 alongside the C128, it was designed to drive monitors such as the Commodore 1084S, which accepts digital RGBI via its 8-pin DIN input. Pin 7 carries a composite monochrome signal (sometimes labelled MONO), allowing the port to also drive monochrome monitors without requiring the full RGBI signal set. Sync signals are supplied as separate horizontal and vertical outputs on pins 8 and 9.
| Pin | Name | Dir | Description |
|---|---|---|---|
| 1 | GND | - | Ground |
| 2 | GND | - | Ground |
| 3 | R | OUT | Red |
| 4 | G | OUT | Green |
| 5 | B | OUT | Blue |
| 6 | I | OUT | Intensity |
| 7 | VIDEO | OUT | Composite Video |
| 8 | HSYNC | OUT | Horizontal Sync |
| 9 | VSYNC | OUT | Vertical Sync |
Notes
- Direction is Computer relative Monitor.
- Signals are digital TTL levels; this is the 80-column output only. The C128’s 40-column output uses a separate DIN connector for composite/S-Video.
- The connector on the computer is female (DE-9F); a cable with a male DE-9 plug connects to the monitor.
- Pin 7 (VIDEO) carries composite monochrome video and is sometimes labelled MONO in repair documentation; it allows the port to drive a monochrome monitor independently of the RGBI colour signals.
- Compatible monitors include the Commodore 1084S (via its 8-pin DIN digital RGBI input using an appropriate adapter) and IBM CGA monitors accepting TTL RGBI with separate H/V sync.
Signals
- GND — Signal ground (pins 1 and 2).
- R — Digital TTL Red signal (pin 3).
- G — Digital TTL Green signal (pin 4).
- B — Digital TTL Blue signal (pin 5).
- I — Intensity (pin 6); combined with R, G, B produces 16 colours in the CGA colour model.
- VIDEO — Composite monochrome video output (pin 7); also labelled MONO in some sources, providing an 80-column monochrome picture without requiring RGBI decoding.
- HSYNC — Horizontal sync output (pin 8).
- VSYNC — Vertical sync output (pin 9).
References
- Commodore 1084S Color Monitor Manual (1988) — Commodore Business Machines; documents the 9-pin D connector pinout for TTL RGBI and Analog RGB modes and electrical specifications.