other signals found on the second video connector) provide access to
the full 12 bits of digital video output produced on the motherboard
by the Denise chip
(4
bits each of R,
G,
and B). Each of these outputs
is 47 Ohm terminated. The pin assignments are Digital Red (R3) on
pin 29, Digital Green (G3) on pin 27, Digital Blue (B3) on pin 25, and
Digital Intensity (BO) on pin 23.
Separate Sync (/HSYNC,
These are the separate, bidirectional,
47
Ohm terminated video
NSYNC)
frame synchronization clocks. The horizontal sync, IHSYNC, is on pin
22; the vertical sync, NSYNC, is on pin 26. As the names imply, these
sync signals are active low.
Composite Sync
Two versions of a composite synchronization signal are available. Pin
(/CSyNC, COMP SYNC)
14, ICSYNC, is an unterminated digital level composite sync; pin 28,
COMP SYNC, is a buffered TTL version of the combined synchroniza-
tion clocks.
Burst
NTSCIPAL colorburst. Pin 18. To obtain the correct PAL colorburst
signal, the video plug-in card must multiply this signal by 1.25 (i.e..
3.55*1.25
=
4.433 MHz).
Pixel Switch (/PU(ELSW)
Background color indicator (color
0),
on a pixel by pixel basis.
47
Ohm terminated, IPIXELSW, pin 30.
AUDIO SIGNALS
Along with access to video signals, audio signals are available at the
Video Slot. The audio signals are the Left and Right audio channels,
on pins
3
and
4
respectively.
RESERVED
FOR
EXPANSION
B2000
EXTENDED
VIDEO SLOT
The original Video Slot has pins l, 2,
5,
35,
and
36
reserved for fu-
ture expansion.
The B2000 Extended Video Slot was designed to provide nearly ev-
ery internal video signal available, plus additional audio signals and
some control lines too. This slot allows much more complex and
powerful devices to be placed in the video slot.
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