AOpen AK77-333 - Prom; SIMM (Single in Line Memory Module); Smbus (System Management Bus); SPD (Serial Presence Detect)

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A memory space in Flash-ROM to simulate E
2
PROM operation, AOpen motherboard uses Shadow E
2
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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SPD is a small ROM or EEPROM device resided on the DIMM or RIMM. SPD stores memory module information such as DRAM
timing and chip parameters. SPD can be used by BIOS
to decide best timing for this DIMM or RIMM.