am79c974 Advanced Micro Devices, am79c974 Datasheet - Page 125

• Manufacturer Part Number: am79c974
• Description: Pcnettm-scsi Combination Ethernet And Scsi Controller For Pci Systems
• Manufacturer: Advanced Micro Devices

Layout #2
This approach uses a “pizza-box” type of motherboard,
which has been incorporated into PC systems and work-
stations. This design reduces the system’s height so
that its casing resembles a pizza box. This is partly the
result of a riser card that enables cards to rest on their
side instead of upright. This approach requires the fol-
lowing and is illustrated in Figure E-4:
External SCSI-2 Bus Cable
An external connector mounted on the mothe-
rboard with routings that connect to the
Am79C974.
The Am79C974 must be as close as possible to
this external connector since this part of the SCSI
Peripheral
External
High-Density
Connector
SCSI-2
High-Density
Termination
SCSI-2
Bracketed card
joining ribbon cable
with high-density
SCSI-2 cable
Figure E-3. Motherboard Layout — Approach #1
Keyboard
Connector
P R E L I M I N A R Y
To SCSI CLK1
and CLK2
Am79C974
To DC Power
Ferrite Bead
Internal SCSI bus cable
to PCI Bus
Am79C974
bus consists of motherboard routings (not just rib-
bon cable).
An internal connector on the motherboard to ac-
commodate internal drives.
On-board regulated terminators for SCSI drives
not mounted within the system. However, should
the user decide to connect a drive internally, termi-
nators are not needed.
If on-board regulated terminators are used, they
should be placed within .1 m (3.937 in) from the
Am79C974.
always on
25
MEMORY
CPU
Connector for
Internal Peripheral
AMD
18681A-65
125