 MC6883 (SAM) |
• The SAM chip creates a synchronous dual-port-RAM, from ordinary DRAM, a dual-phase CPU (MC6809), and a graphics chip (MC6847). • Bill created the system architecture and designed all the logic in the SAM chip. • Keywords: Hardware, Low Power Schottky, DRAM, Address Multiplexer, Dual Port RAM, Video Mode Selection. * SAM is a contraction for "Synchronous Address Multiplexer." |
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• MC6883 was the most profitable chip among all Motorola's numerous Low Power Schottky (LS) parts. • It enabled several video game consoles and the Motorola's first, highly profitable computer. • SAM architecture was challenging because it had to directly interface with the MC6847 (without modification) and multiple DRAM configurations, and use just 40 pins. Since the MC6847 was not designed to use DRAM, Bill created a digital PLL inside the MC6883 to resynchronize the MC6847 to meet precise DRAM specifications. |
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Leadership / Management • Bill created and led the SAM project. Theory / R&D • Bill's development experience with DRAM controllers (MC6883) enabled multiple derivative products. • This includes Bill’s numerous insights in hardware design (CMOS design, LS, pipelining, memory architectures, DRAM timing, I/O Drivers, and Bus Protocol). Software • Bill architected special test software and supporting hardware for the initial chip "bring up" for the MC6883 which served as a system-integration chip for the color computer. Hardware • Bill designed all of the logic in the MC6883 and MC6847. |
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By pushing beyond the current state-of-the-art, there are these opportunities: • Although Windows PCs have dominated for years, their high power consumption and high silicon complexity have severely slowed the progress of battery-efficient, low-cost, portable applications. • As the SAM design demonstrated, fresh re-thinking of the system, as a whole, can make enormous simplifications, thereby driving down battery-drain and costs (e.g. See the Negroponte $100 laptop per child project). |
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• MC6883 SAM and MC6847 Interaction |
