21064 fact sheet

The Digital Equipment Corporation's 21064, a 150 MHz microprocessor, is the inaugural chip implementing Digital's 64-bit Alpha RISC architecture. Designed for speed, multiple instruction issue, and multiprocessor support, it is built on a 0.75 micron CMOS process, featuring super-scalar and super-pipelined design with dual instruction issue.

Key Features:

• Architecture: Implements the Advanced Alpha RISC, optimized for high performance and multiprocessor systems.
• Performance: Operates at a 150 MHz cycle time, achieving a peak instruction execution of 300 MIPS.
• Pipelining: Employs a dual-pipelined architecture with a 7-stage pipeline for integer/memory operations and a 10-stage pipeline for floating-point operations.
• On-chip Components: Includes a pipelined floating-point unit, 8 Kbyte data cache, 8 Kbyte instruction cache, a demand paged memory management unit with Translation Buffers (TBs), a write buffer, parity/ECC generators, and programmable performance counters.
• Data Support: Supports IEEE single/double precision and VAX F/G_floating, longword, and quadword data types.
• Memory Management: Utilizes a 64-bit virtual address space (implementing a 43-bit subset) and supports a 16 Gbyte physical address space, with flexible management via PALcode.
• PALcode: A privileged software library that handles critical functions like interrupts, exceptions, task switching, and atomic multi-instruction sequences.
• External Support: Features on-chip control for external secondary cache (0-8 Mbytes, programmable size/speed) and a selectable 64-bit or 128-bit data bus.
• Microarchitecture: Comprises four independent functional units: the Integer Execution Unit (Ebox), Floating Point Unit (Fbox), Load/Store/Address Unit (Abox), and Branch Unit, alongside the central control unit (Ibox).

Operating Characteristics:

• Voltage: 3.3V
• Power Dissipation: 23W typical, 27.5W maximum
• Transistor Count: 1.68 million
• Die Size: 13.9mm x 16.8mm
• Package: 431 pin PGA

Availability & Pricing: Samples were available in February 1992, priced at $3375 each (June 1992). Volume quantities became available in July 1992, starting at $1650 for 1,000 pieces.