Memory - Compaq Deskpro AP500 Supplementary Manual

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HITE APER
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M
E M O R Y
The Compaq Professional Workstation AP500 uses 100-MHz Registered ECC Synchronous
DRAM (SDRAM) and supports up to 1 GB of memory. SDRAM is designed to accommodate
higher processor speeds and provides faster memory operation with burst data rates of up to
four times that of standard page-mode DRAMs. The new burst mode addresses an entire block
of data rather than one piece at a time. Most importantly, SDRAM is synchronized with the
CPU system clock to allow continuous data flow. Estimated performance increases are 2% for
cached systems and 10% for non-cached systems.
100-MHz SDRAM is required to work with the 100-MHz Front Side Bus (FSB), which is an
integral part of high-speed systems. 100-MHz SDRAM is designed to accommodate higher
microprocessor speeds and to provide faster memory operation.
CUSTOMER BENEFITS
There are clear benefits to SDRAM compared to the previous memory technology, EDO
(extended data output) DRAM. Some key benefits are:
Increased performance. Customers will experience greater CPU responsiveness with
SDRAM technology. The 100-MHz SDRAM will support high-speed Pentium II 400-
MHz and 450-MHz technologies that EDO DRAM cannot support.
Faster bus speeds. SDRAM can run up to 100 MHz, while the maximum bus speed that
EDO DRAM can run is 66 MHz.
Perfect match for demanding applications. As graphics and software programs
become more and more complex, SDRAM is better suited to handle these advances
compared to EDO SDRAM because of its higher bus speed.
Q. Compaq Professional Workstation AP500 uses registered memory. What is the
difference between registered and unregistered memory?
A. Registered memory is buffered memory. Buffered DIMMs use buffer logic chips on
their control lines to reduce loading on the system board. This buffering action
increases the maximum size of DIMM module sockets on the system board. Unbuffered
DIMMs do not use any buffer logic chips, thus achieving slightly faster operation due
to the elimination of the propagation delay of the logic buffer. The increase in speed
comes at the tradeoff of reducing the maximum size of DIMM modules on the system
board, which results in smaller memory capacity.
Q. Can I use older memory from my installed base of Compaq Professional
Workstation systems in the new AP500 machine?
A. The Compaq Professional Workstation AP500 uses the same memory as the Compaq
Professional Workstation AP400; however, the AP500 memory is not interchangeable
with the AP200, 5000, 5100, 6000, or 8000 products. The AP200 uses unregistered
DIMMS, and the remaining products use 66-MHz EDO memory.
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Compaq Workstations - Key Techn ologies