PPC7A Product Manual
Functional Description
8-12
1
st
Edition
Ethernet Controller
The GT64260 device provides two ethernet MACs. To interface these to the physical interface two
National Semiconductor DP83846s are used.
The DMA controllers handle data transfers between CPU memory and on-chip memory with the
Ethernet Controller arbitrating between DMA channels to minimise underflow or overflow.
Automatic packet deletion on receive (runt packets or after a collision) and packet re-transmission after a
collision on transmission are supported. This minimises bus traffic by removing unnecessary accesses to
shared memory. The network addresses (Ethernet number) are factory configured.
Connection to the Ethernet controller is via the P2 connector (see Chapter 5). Eight associated status
LEDs (DS16 to DS23) are mounted on the rear of the board near the Ethernet PHY chips (see the
Software Programmable LEDs section). The default functions of these LEDs are link, TX activity, RX
activity status, and 100BaseT, but they may be overridden by the software.
SCSI Scripts Processor
The NCR53C860 SIOP executes commands, in the form of SCSI scripts. It has a PCI interface and a
DMA controller, which are used to access the scripts and data held in system memory. The SIOP can
transfer data at 7 Mbytes/second asynchronously and 20 Mbytes/second synchronously or 14
Mbytes/second asynchronously. Connection to the SCSI bus is made through the P2 connector. The
pinout is given in Chapter 5.
The PPC7A
has an on-board active SCSI terminator, which may be enabled or disabled with a jumper
(see the E13 description in Chapter 4). The SCSI specification allows a maximum cable stub length of
10 cm. If the SCSI bus connections are taken directly from the backplane J2 connector, then the PPC7A
may be located anywhere on the SCSI bus and the terminator should only be enabled if the PPC7A
is at
the end of the SCSI bus. Otherwise, the PPC7A
must be at the end of the SCSI bus and the terminator
must be enabled.
A software programmable SCSI Activity LED (LED DS11) is mounted on the back of the board. See the
Software Programmable LEDs section and the SCSI Activity LED Register description for more details.
VGA graphics Processor
The PPC7A
uses an Asiliant Technologies 69000 or 69030 PCI to VGA graphics processor device. This
is a totally integrated high performance graphics accelerator with integrated 2Mbytes (4Mbytes with the
69030) of fast graphics SDRAM.
The 69000 can provide pixel clock rates at up to 135Mhz (170Mhz with the 69030) and pixel colour
depths of up to 24 bit. This gives the maximum resolutions of:
•
1280 x 1024 x 8 @ 75Hz (1280 x 1024 x 24 @ 75 Hz with 69030)
•
1024 x 768 x 16 @ 85Hz (1024 x 768 x 24 @ 85 Hz with 69030)
•
800 x 600 x 24 @ 85Hz
Universe II
This provides the VMEbus Interface. See later.
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