Xycom XVME-653, Manual

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Chapter 1 – Introduction
1-3
Caution
The IDE controller supports enhanced PIO modes, which reduce the cy-
cle times for 16-bit data transfers to the hard drive. Check with your
drive manual to see if the drive you are using supports these modes. The
higher the PIO mode, the shorter the cycle time. As the IDE cable length
increases, this reduced cycle time can lead to erratic operation. As a re-
sult, it is in your best interest to keep the IDE cable as short as possible.
The PIO modes are selected in the BIOS setup (see p. 3-4). The Auto-
config will attempt to classify the connected drive if the drive supports
the auto ID command. If you experience problems, change the Transfer
Mode: to Standard .
Caution
The total cable length must not exceed 18 inches. Also, if two drives are
connected, they must be no more than six inches apart.
VMEbus Interface
The XVME-653/658 uses the PCI local bus to interface to the VMEbus. The VMEbus
interface supports full DMA to and from the VMEbus, integral FIFOs for posted writes,
block mode transfers, and read-modify-write operations. The interface contains one
master and four slave images that can be programmed in a variety of modes to allow the
VMEbus to be mapped into the XVME-653/658 local memory. This makes it easy to
configure VMEbus resources in protected and real mode programs. The XVME-658 and
the XVME-653/31x modules also incorporate onboard hardware byte-swapping (see
Table 1-1).
Card Expansion Options
The XVME-653/658 supports optional PMC (PCI Mezzanine Card), PC/104, short ISA,
or PCI expansion using XVME-976 expansion modules. The XVME-976/201 provides
one PCI Mezzanine Card (PMC) site and one 16-bit PC/104 site. The XVME-976/202
provides one 16-bit short ISA expansion site. The XVME-976/203 provides two PMC
sites. The XVME-976/204 provides two 16-bit PC/104 sites. The XVME-976/205 pro-
vides one PCI card expansion site. All XVME-976 modules are designed to plug directly
into the XVME-653/658 using the 80-pin interboard connectors.
Onboard Memory
DRAM Memory
The XVME-653/658 has two 72-pin SIMM memory sites, providing up to 256 MB of
DRAM. The memory sites can be populated with standard fast page mode memory or
enhanced data out memory (EDO). EDO memory is designed to improve DRAM read
performance. Using EDO memory improves the back-to-back burst timing to 5-2-2-2
from the 5-3-3-3 of standard memory. The XVME-653/658 also supports error checking