Specifications

CHAPTER 4
Expansion Features
The PCI Bus Communications Slot 59
Figure 4-5 Video data timing
The PCI Bus Communications Slot 4
The main logic board has a separate slot for an optional communications card. The
communications slot on the Macintosh Performa 6400 computer is a PCI-bus based
communications slot rather than a processor direct PDS-based communications slot like
that found on the Power Macintosh 5200 and 6200 computers.
The electrical interface of the communications slot includes a parallel bus, the SCC lines,
and lines for supporting modem audio. The PSX custom IC provides bus conversion
from the host PowerPC 603e bus to the PCI parallel bus. Cards that use the
communications slot are memory mapped into the I/O space of the Macintosh Performa
6400 computer via the parallel bus. The communications slot supports SCC port A
(modem port) for a universal modem card that is compatible with both the
communications slot in the Power Macintosh 5200 and 6200 computers and the PCI
communications slot in the Macintosh Performa 5400 and 6400 computers.
Y 0
LLCLK
vdcCREFB
HREF
Y 7–0
UV 7–0
Start of a video line
Y1 Y2 Y3 Y4 Y5
U 0 V0 U2 V2 U4 V4
Y and UV data valid on the rising edge of LLCLK
when HREF and CREFB are high
Yn-5
LLCLK
vdcCREFB
HREF
Y 7–0
UV 7–0
End of a video line
Yn-4 Yn-3 Yn-2 Yn-1 Yn
Un-5 Vn-5 Un-3 Vn-3 Un-1 Vn-1