WD16

Western Digital 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
Launched1976; 48 years ago (1976)
Common manufacturer
Performance
Max. CPU clock rateto 3.3 MHz
Data width16
Address width16
Architecture and classification
Instruction setPDP-11 like
Number of instructions119
Physical specifications
Package
History
Successornone

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.[1] The instruction set and microcoding were created by Dick Wilcox and Rich Notari.[2] 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.[3]

The WD16 is best known for its use in Alpha Microsystems' AM-100 and AM-100/T processor boards.[4] A prototype was demonstrated in 1977.[5] As of 1981 there were at least 5,000 Alpha Micro computers based on the WD16.[6] As late as 1982, WD16-based Alpha Micros were still being characterized as "supermicros."[7] The WD16 was superseded by the Motorola 68000 in June 1982.[8]

  1. ^ Flystra, Daniel (April 1977). "New Hobbyist System Supports Timesharing" (PDF). Byte. 2 (4): 142–144. Retrieved 21 November 2022.
  2. ^ Wilcox, Dick (January 1977). "A PDP-11-Like 16-Bit Micro for the S-100 Bus". Dr. Dobbs's Journal of Computer Calisthenics and Orthodontia. 2 (1): 3–7. Retrieved 14 June 2022.
  3. ^ MCP-1600 Microprocessor Users Manual (PDF). Western Digital. 1975. Retrieved 28 April 2022.
  4. ^ Stan, Viet (May 1983). "The Battle of the Disk Operating Systems" (PDF). Computers & Electronics. 21 (5): 19. Retrieved 8 June 2023.
  5. ^ Craig, John (April 1977). "Around the Industry" (PDF). Kilobaud: The Small Computer Magazine (4): 10. Retrieved 23 November 2022.
  6. ^ Cite error: The named reference :1 was invoked but never defined (see the help page).
  7. ^ Fox, Tom (January 1982). "Business Systems for '82". Interface Age. 7 (1): 75. Retrieved 3 November 2022.
  8. ^ "Alpha Microsystems makes record sales". InfoWorld. 4 (44): 11. November 8, 1982. Retrieved 3 November 2022.