The Macintosh II video card provide scolor capability for simultaneous display of up to 256 colors on the Apple High Resolution Color Monitor. With the card's three 8 bit digital to analog converters (RGB) there are more than 16 million possible colors to choose from.
Color Modes
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* One bit per pixel for 2 color output
* Two bits per pixel for 4 colors
* Four bits per pixel for 16 colors
* Optional Eight bits per pixel for 256 colors
Video Signals
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* RS343 Analog RGB for Apple High Resolution Color Monitor
* RS343 Analog Green signal for Apple High Resolution Monochrome Monitor
* RS170 Composite interlaced video for analog RGB monitors, film recorders and projection TV's
* RS170 Analog Green signal for composite interlaced video with sync for analog monochrome monitors, film recorders, and projection TV's
Hardware Features
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* Multiple video card operation for larger screen area For example, 2 cards handle 2 video screens for viewing different or large format documents.
* Standard VIDEO RAM configuration of 256K for 1, 2, and 4 bit color modes 8 chips of 150NS 64x4 KBit Video RAM.
* Upgraded VIDEO RAM configuration of 512K for 8 bit color mode 8 additional chips of 150NS 64x4 Kbit Video RAM
*** Video RAM contains a shift register for the copying of rows of bits from the RAM array. This allows reads and writes to the RAM array and the shift register simultaneously. This is not a feature of standard or common RAM and is necessary to the workings of the video card.
* Two Oscillators provide timing signals of:
30.24MHz for Macintosh II monitors (RS343)
12.27MHz for RS170 monitors (Composite Monochrome interlaced video)
* Slot independent operation
* Triple 8 bit digital to analog converters for 2 to the 24th colors equalling 16.8 million.
Article Change History:
14 Feb 1995 - Reviewed for technical accuracy, corrected spelling of sync.
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