WD16
WD16 microprocessor in five 40-pin packages installed on an Alpha Microsystems AM-100 CPU board which connects to a S-100 bus. | |
| General information | |
|---|---|
| Launched | 1976 |
| Common manufacturer | |
| Performance | |
| Max. CPU clock rate | to 3.3 MHz |
| Data width | 16 |
| Address width | 16 |
| Architecture and classification | |
| Instruction set | PDP-11 like |
| Number of instructions | 119 |
| Physical specifications | |
| Package |
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| History | |
| Successor | none |
The WD16 is a 16-bit microprocessor introduced by Western Digital in October 1976. It is based on the MCP-1600 chipset, a general-purpose design that was also used to implement the DEC LSI-11 low-end minicomputer and the Pascal MicroEngine processor. The three systems differed primarily in their microcode, giving each system a unique instruction set architecture (ISA).
The WD16 implements an extension of the PDP-11 instruction set architecture but is not machine code compatible with the PDP-11. The instruction set and microcoding were created by Dick Wilcox and Rich Notari. The WD16 is an example of orthogonal CISC architecture. Most two-operand instructions can operate memory-to-memory with any addressing mode and some instructions can result in up to ten memory accesses.
The WD16 is implemented in five 40-pin DIP packages. Maximum clock speed is 3.3 MHz. Its interface to memory is via a 16-bit multiplexed data/address bus.
The WD16 is best known for its use in Alpha Microsystems' AM-100 and AM-100/T processor boards. A prototype was demonstrated in 1977. As of 1981 there were at least 5,000 Alpha Micro computers based on the WD16. As late as 1982, WD16-based Alpha Micros were still being characterized as "supermicros." The WD16 was superseded by the Motorola 68000 in June 1982.