Improving Information for Social Policy Decisions -- The Uses of Microsimulation Modeling: Volume II, Technical Papers (1991)
Chapter: Advances in Primary Memory
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IBM’s new RT-based computer system is reputed to execute at a rate of 20 MIPS and to have a system cost of about $20,000.34 In fact, the machine was announced with speeds of 27 and 41 MIPS and 7–13 MFLOPS (million floating point operations per second), making it one of the most cost-effective workstations available for numerical computation.
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Evans and Sutherland has announced the ES-1, a moderately parallel supercomputer running a version of UNIX. The two-processor ES-1/200, priced at about $2.2 million, contains 256–512 MB of RAM and can execute at peak performance 400 MFLOPS.35
Advances in Primary Memory
Primary, or immediate access, memory is an essential component of a computer system. Primary memory is characterized by being able to access or modify any location within it in an equal and very short amount of time. Primary memory is a strategic resource for implementation of microsimulation models. Limited amounts of primary memory force modeling implementation decisions to make use of secondary memory, which often forces uneasy decisions between model generality and implementation efficiency. Sufficient amounts of primary memory would ease the task of model implementation and obviate the need for many such compromises.
The production of primary memory is now an exacting photolithographic process. Technical advances in improving the density of memory elements, as well as increasing the efficiency of the production process, have steadily raised memory capacities per solid state chip and have lowered the cost per unit of memory. The following evidence indicates the technical progress that is being made in primary memory technology:
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After an increase in memory chip prices in 1986–1988, caused by restrictions on foreign imports, prices have continued their downward trend. Chips of 1 MB assembled as SIMMs (single in-line memory modules) are now almost as low as $100.
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Production of 4-MB DRAM chips has begun. According to Byte magazine, “Hitachi America says it already has the 4-megabit chips in volume. Toshiba, which fabricated its first 4-megabit chip last November [1988], expects to be making them at a rate of 1 million per month by next March [1990]. IBM has three facilities in various stages of 4-megabit DRAM production. Fujitsu, Motorola, NEC, Mitsubishi, Oki Electric, Sanyo, Sharp, and U.S. Memories,36
