Every node was connected to every other node using a Quadrics elan3 interconnect and the systems were designed and used primarily for high-performance technical computing. With the exception of the instructions that specify the former two conditions, there are versions that perform signed and unsigned compares. The CPU state registers integer and floating point, program counter, condition codes, etc. The Irongate-2 was used by Samsung in their UP motherboard. The choice predictor records the history of the local and global predictors to determine which predictor is the best for a particular branch. Values transferred between register banks instruction streams add a delay. The second reason was the requirement to retain the fast cycle times of implementations.

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Floating point exceptions are imprecise – in fact, don’t produce eec at all, but set a condition bit on an error. The format retains the opcode field but replaces the others with a bit function field, which contains an integer specifying a PAL subroutine. By using this site, you agree to the Terms of Use and Privacy Policy. There are also thirty-two 32 bit special function registers.

There are sixteen 32 bit global registers which can be shared by all excution units and sixteen register “caches” – similar to the SPARC register windows, but not overlapping originally four banks. Views Read Edit View history.

Post a Comment Comment. This number of registers was deemed not to be a major issue in respect to performance and future growth, as thirty-two registers could support at least eight-way instruction issue.


The concept of a separate instruction for multiplication that returns the most significant half of a result was taken from PRISM. It also defined registers that were optional, implemented only if the implementation required them.

There was no entry for register R31 because in the Alpha architecture, R31 is hardwired to zero and is read-only. Careful attention to circuit design, a hallmark of the Hudson design team, like a huge centralized clock circuitry, allowed them to run the CPU at higher speeds, even though the microarchitecture was fairly similar to other RISC chips.


These instructions were first introduced in the A EV56 microprocessor and are present in all subsequent implementations. The external interface consisted of a bidirectional bit double data rate DDR data bus and two bit unidirectional time-multiplexed address allpha control buses, one for signals originating from the Alpha and one for signals originating from the system.

Later, the Alpha included byte-word extensions, a set of instructions to manipulate 8-bit and bit data types. It has a peak execution rate of six instructions per cycle and could sustain four instructions per cycle.

Each integer register file contained 80 entries, of which 32 are architectural registers, 40 are rename registers and 8 are PAL shadow registers. It’s a very clean embedded architecture, ef6 designed for high level applications, but very effective and scalable – something that can’t be said for all Intel’s processor designs. The global predictor is a single-level, entry branch history table.

The displacement field contains a signed integer and if the value of the integer is positive, if the branch is taken then the program counter is incremented.

While this was not to be, Alpha has nevertheless had a reasonably long life.


However, development of the workstation was well ahead of the PRISM, and the engineers proposed that they release the machines using the MIPS R processor instead, [8] moving its release date up considerably.

Count Extensions CIX was an extension to the architecture which introduced three instructions for counting bits. The die measured The R31 and F31 registers were hardwired to zero and writes to those registers by instructions are ignored. The had thirty two 32 bit registers and thirty two 32 bit or sixteen 64 bit floating point registers.

It has a 1,entry branch prediction table. Memory access, storing bytes and words”. This method of dual-porting enabled any combination of reads or writes to the cache every processor cycle. The and processors were used by NetApp in various network-attached storage systems, while the and processors were used by Cray in their T3D and T3E massively parallel supercomputers. It also ended up a dismal commercial failure.

Alpha – Wikipedia

The EV68CB used a 1. Improvements were a higher operating frequency of 1. The ddc is the same as the integer operate format except for the replacement of the 5-bit Rb field and the 3 bits of unused space with an 8-bit literal field which is zero-extended to a bit operand. Alpha was implemented in microprocessors originally developed and fabricated by DEC.