User Guide

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SDRAM is one of the DRAM technologies that allow DRAM to use the same clock as the CPU host bus (EDO and FPM are
asynchronous and do not have clock signal). It is similar as PBSRAM
to use burst mode transfer. SDRAM comes in 64-bit
168-pin DIMM
and operates at 3.3V. AOpen is the first company to support dual-SDRAM DIMMs onboard (AP5V), from Q1 1996
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A memory space in Flash-ROM to simulate E
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PROM operation, AOpen motherboard uses Shadow E
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PROM for jumper-less and
battery-less design
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SIMM socket is only 72-pin, and is only single side. The golden finger signals on each side of PCB are identical. That is why it
was called Single In Line. SIMM is made by FPM or EDO
DRAM and supports 32-bit data. SIMM had been phased out on
current motherboard design.
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SMBus is also called I2C bus. It is a two-wire bus developed for component communication (especially for semiconductor IC).
For example, set clock of clock generator for jumper-less motherboard. The data transfer rate of SMBus is only 100Kbit/s, it
allows one host to communicate with CPU and many masters and slaves to send/receive message.
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