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Additional Instructions

In addition to the standard memory-reference instructions, other types of instruction are required in a computer.

Instructions are required to alter the sequence in which commands are executed, so that the computer can perform different calculation steps depending on circumstances. These instructions, since they refer to the memory location from which execution continues, are similar in form to memory-reference instructions, but they do not require a destination register, and so use that field for another purpose: to indicate the condition to be fulfilled for a branch to be taken.

Also, various operations are required that act only on a single register; most notably, left and right shifts of the bits contained therein.

As well, this architecture includes data formats which have memory-reference instructions that apply to them, but which do not fit in registers, and whose memory-reference instructions, therefore, must include the addresses of two memory locations, as well as an additional field indicating the length of the operands involved.

These are the types of instructions that will be described in this section.

Some of these instructions refer to registers other than the basic ones described in the preceding section. The short vector instructions, which will be described in a section of their own, use a bank of 16 registers which are 256 bits in length, and which may contain two, four, eight, sixteen, or thirty-two values of various lengths. The supplementary load and store instructions operate on the base registers, and on three other banks of registers similar to the base registers that play a role in memory-reference instructions in some modes other than the normal mode, particularly the scratchpad mode.

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