Specifications

Little Board/P5i Technical Manual
2–28
 The byte-wide device is accessed as an 8-bit device, compared to DRAM which is accessed as 64
bits.
 The device is accessed from the PC expansion bus which is much slower than the high-speed
processor memory bus.
You can improve performance substantially by copying the contents of the byte-wide device into DRAM
and executing the DRAM copy.
2.10.2 Byte-Wide S0’s Interaction with the OEM Flash Memory
Access to the byte-wide socket is integrated with access to the (optional) Flash memory device,
designated the OEM Flash memory in SETUP. The OEM Flash memory device, 768K of Flash memory,
is available if your board is equipped with a 1M byte Flash device. The standard Flash device is 256K
bytes.
The OEM Flash memory acts as a second byte-wide device (S1), in that you access it through the same
code mechanisms as the byte-wide socket. (These mechanisms are described in Chapter 3.)
The first 256K bytes of the Flash memory device hold the ROM BIOS and other system software. The
remaining portion of the 1M byte device can be used by OEMs or end-users in a manner similar to the
byte-wide socket. Models with a 1M byte Flash device can be special-ordered from Ampro. (Contact
your Ampro Sales Representative for details.)
2.10.3 Jumpering the Byte-Wide Socket
You must jumper the byte-wide sockets for the device you install. Jumper array W15 configures S0 for a
particular device type. Table 2–21 to Table 2–23 show how to install jumpers for supported memory
devices. Table 2–24 describes the byte-wide socket signals that correspond to each jumper pin.
2.10.4 Using EPROMs
If you install an EPROM in socket S0, and you have an external backup battery connected to J16, make
sure the jumper on W2 is removed and the jumper on W21 is on 1/2 to prevent premature discharge of
the battery. Some EPROMs draw current through their chip select lines (or other pins) when powered
down.