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AP440FX Motherboard Technical Product Specification
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1.6 Main System Memory
The motherboard has four 72-pin tin-lead SIMM sockets that make it possible to install up to
128 MB of RAM. The sockets support 1M x 32 (4 MB) single-sided modules, 2M x 32 (8 MB),
4M x 32 (16 MB), and 8M x 32 (32 MB) single- or double-sided modules. Minimum memory size
is 8 MB and maximum memory size, using four 8M x 32 SIMM modules, is 128 MB. Memory
timing requires 60 ns fast page devices or, for optimum performance, 60 ns EDO DRAM. Both
parity and non-parity memory modules are supported. With parity SIMMs, the board can be
configured to support ECC operation.
The four sockets are arranged in two banks of two sockets each. The sockets are designated
Bank 0 and Bank 1. Each bank provides a 64/72-bit wide data path. Both SIMMs in a bank must
be of the same memory size and type, although the types and sizes of memory may differ between
banks. Bank 0 only, Bank 1 only, or both of the banks may be populated. There are no jumper
settings required for the memory size or type, which is automatically detected by the BIOS. Use
only tin lead SIMMs when adding DRAM.
1.6.1 DRAM
EDO (or Hyper Page) DRAM is designed to improve the DRAM read performance. EDO DRAM
holds the memory data valid until the next memory access cycle, unlike standard fast page mode
DRAM that tri-states the memory data when the precharge cycle occurs, prior to the next memory
access cycle.
1.6.2 Parity and ECC DRAM
Memory error checking and correction is supported by parity SIMMs. With parity SIMMs, the
board can be configured to support ECC memory operation. Parity SIMMs are automatically
detected, but the user must enter Setup to configure the SIMMs for either Parity or ECC operation.
Parity memory detects single bit errors. ECC memory detects double bit errors and corrects single
bit errors. Errors may be generated by a defective memory module, by different speeds of memory
modules, or by DMA or memory conflicts.
1.7 Chipset
The Intel 82440FX PCIset consists of the 82441FX PCI Bridge and Memory controller (PMC) and
the 82442FX Data Bus Accelerator (DBX). The Intel 82371SB PCI ISA/IDE Xccelerator (PIIX3)
bridge, provides the connection between the ISA and PCI buses.
1.7.1 82441FX PCI Bridge and Memory Controller (PMC)
The 82441FX comes in a 208 pin QFP package and provides the following features:
• Microprocessor interface control
Pentium Pro processor host bus up to 66 MHz
32-bit addressing