The Multimedia Acceleration eXtensions or MAX are instruction set extensions to the

Hewlett-Packard The Hewlett-Packard Company, commonly shortened to Hewlett-Packard ( ) or HP, was an American multinational information technology company headquartered in Palo Alto, California. HP developed and provided a wide variety of hardware components ...

PA-RISC PA-RISC is an instruction set architecture (ISA) developed by Hewlett-Packard. As the name implies, it is a reduced instruction set computer (RISC) architecture, where the PA stands for Precision Architecture. The design is also referred to as ...

instruction set architecture In computer science, an instruction set architecture (ISA), also called computer architecture, is an abstract model of a computer. A device that executes instructions described by that ISA, such as a central processing unit (CPU), is called an ' ...

(ISA). MAX was developed to improve the performance of multimedia applications that were becoming more prevalent during the 1990s. MAX instructions operate on 32- or 64-bit

SIMD Single instruction, multiple data (SIMD) is a type of parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (ISA), but it should ...

data type In computer science and computer programming, a data type (or simply type) is a set of possible values and a set of allowed operations on it. A data type tells the compiler or interpreter how the programmer intends to use the data. Most progra ...

s consisting of multiple 16-bit integers packed in

general purpose registers A processor register is a quickly accessible location available to a computer's processor. Registers usually consist of a small amount of fast storage, although some registers have specific hardware functions, and may be read-only or write-only. ...

. The available functionality includes additions, subtractions and shifts. The first version, MAX-1, was for the

32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32-bit units. Compared to smaller bit widths, 32-bit computers can perform large calculation ...

PA-RISC 1.1 ISA. The second version, MAX-2, was for the

64-bit In computer architecture, 64-bit Integer (computer science), integers, memory addresses, or other Data (computing), data units are those that are 64 bits wide. Also, 64-bit central processing unit, CPUs and arithmetic logic unit, ALUs are those ...

PA-RISC 2.0 ISA.

Notability

The approach is notable because the set of instructions is much smaller than in other multimedia CPUs, and also more general-purpose. The small set and simplicity of the instructions reduce the recurring costs of the electronics, as well as the costs and difficulty of the design. The general-purpose nature of the instructions increases their overall value. These instructions require only small changes to a CPU's arithmetic-logic unit. A similar design approach promises to be a successful model for the multimedia instructions of other CPU designs. The set is also small because the CPU already included powerful shift and bit-manipulation instructions: "Shift pair" which shifts a pair of registers, "extract" and "deposit" of bit fields, and all the common bit-wise logical operations (and, or, exclusive-or, etc.). This set of multimedia instructions has proven its performance, as well. In 1996 the 64-bit "MAX-2" instructions enabled real-time performance of

MPEG-1 MPEG-1 is a standard for lossy compression of video and audio. It is designed to compress VHS-quality raw digital video and CD audio down to about 1.5 Mbit/s (26:1 and 6:1 compression ratios respectively) without excessive quality loss, making ...

and

MPEG-2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic video coding format, coding of moving pictures and associated audio information". It describes a combination of Lossy compression, lossy video compression and ...

video while increasing the area of a RISC CPU by only 0.2%.

Implementations

MAX-1 was first implemented with the

PA-7100LC The PA-7100LC is a microprocessor that implements the PA-RISC 1.1 instruction set architecture (ISA) developed by Hewlett-Packard (HP). It is also known as the ''PCX-L'', and by its code-name, ''Hummingbird''. It was designed as a low-cost micr ...

in 1994. It is usually attributed as being the first

extensions to an ISA. The second version, MAX-2, was for the

PA-RISC 2.0 ISA. It was first implemented in the

PA-8000 The PA-8000 (PCX-U), code-named ''Onyx'', is a microprocessor developed and fabricated by Hewlett-Packard (HP) that implemented the PA-RISC 2.0 instruction set architecture (ISA). Hunt 1995 It was a completely new design with no circuitry deriv ...

microprocessor released in 1996. The basic approach to the arithmetic in MAX-2 is to "interrupt the carries" between the 16-bit subwords, and choose between modular arithmetic, signed and unsigned saturation. This requires only small changes to the arithmetic logic unit.

MAX-1

MAX-2

MAX-2 instructions are register-to-register instructions that operate on multiple integers in 64-bit quantities. All have a one cycle latency in the

microprocessor and its derivatives. Memory accesses are via the standard 64-bit loads and stores. The "MIX" and "PERMH" instructions are a notable innovation because they permute words in the register set without accessing memory. This can substantially speed many operations.

References

Multimedia Acceleration eXtensions (MAX-1 and MAX-2) PA-RISC CPU Architecture
''OpenPA.net'' {{Multimedia extensions Computer-related introductions in 1994 HP microprocessors SIMD computing