Macintosh Displays: Overview of Sense Codes and Adapters
Older Macintosh computers and Apple video cards do not have reprogrammable video drivers that allow them to switch to higher resolutions. If a Multiple Scan Display is connected to an older Macintosh or video card, it will be limited to 640 x 480 resolution.
Macintosh computers and video cards that fall into this class are:
- Video Cards - 4*8, 8*24, and 8*24GC
- LC , LC II, LC III (except 475, 476, and 630)
- Performa (except the 475, 476, and 630 family)
- PowerBook
- Duo Dock and MiniDock*
- Macintosh II family
The sense adapter attaches to the display's video cable, and has a sense code for a higher resolution.
* - The Duo Dock does not require a video adapter to change resolutions when System 7.5 is installed.
Sense Adapters
Sense code cable adapters allow older Macintosh and video cards to display higher resolutions on multiple scan displays. The adapters have a sense code for a higher resolution. This tricks the Macintosh into thinking it is hooked to a fixed frequency display like our 16-inch and 21-inch RGB displays.
The other solution, when using a multiple scan display, is to use a programmable display card like a Macintosh Display Card 24AC. Because this card is fully capable of recognizing the multiple scan sense codes and changing resolutions without restarting, even older Macintosh Systems work fine if they have a 24AC card.
Sense Code Adapter Specifications
832 by 624 Adapter - 16-inch Display
DB15M DB15F Pin Assignments
1 1 RED GND
2 2 RED VIDEO
3 3 C SYNC
5 5 GREEN VIDEO
6 6 GREEN GND
9 9 BLUE VIDEO
11 11 C & V SYNC GND
12 12 V SYNC
13 13 BLUE GND
14 14 H SYNC GND
15 15 H SYNC
SHELL SHELL
Notes:
PINS 4 & 10 JUMPERED TOGETHER ON DB15 PLUG END.
1152 by 870 Adapter - 21-inch Display
DB15M DB15F Pin Assignments
1 1 RED GND
2 2 RED VIDEO
3 3 C SYNC
5 5 GREEN VIDEO
6 6 GREEN GND
9 9 BLUE VIDEO
12 12 V SYNC
13 13 BLUE GND
14 14 H SYNC GND
15 15 H SYNC
11 11 C & V SYNC GND
SHELL ð SHELL
Notes:
PINS 4,7,10,11 JUMPERED TOGETHER ON DB15 PLUG END.