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In a computer's central processing unit (CPU), the accumulator is a register in which intermediate arithmetic logic unit results are stored.. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to cache or main memory, perhaps only to be read right back again for use in the next operation.
The hardware unit that performs the operation is known as a multiplier–accumulator (MAC unit); the operation itself is also often called a MAC or a MAD operation. The MAC operation modifies an accumulator a : a ← a + ( b × c ) {\displaystyle a\gets a+(b\times c)}
add the contents of a memory cell to the accumulator. 3: TAC: Test accumulator contents performs a sign test on the contents of the accumulator; if minus, jump to a specified memory cell. 4: SFT: Shift shifts the accumulator x places left, then y places right, where x is the upper address digit and y is the lower. 5: OUT: Output
The accumulator can be viewed as a truncated rate 1 recursive convolutional encoder with transfer function / (+), but Divsalar et al. prefer to think of it as a block code whose input block (, …,) and output block (, …,) are related by the formula = and = + for >.
In 1967, Fairchild introduced the first ALU-like device implemented as an integrated circuit, the Fairchild 3800, consisting of an eight-bit arithmetic unit with accumulator. It only supported adds and subtracts but no logic functions. [7] Full integrated-circuit ALUs soon emerged, including four-bit ALUs such as the Am2901 and 74181.
Folds can be regarded as consistently replacing the structural components of a data structure with functions and values. Lists, for example, are built up in many functional languages from two primitives: any list is either an empty list, commonly called nil ([]), or is constructed by prefixing an element in front of another list, creating what is called a cons node ( Cons(X1,Cons(X2,Cons ...
The Mano machine is a computer theoretically described by M. Morris Mano.It contains a central processing unit, random access memory, and an input-output bus.Its limited instruction set and small address space limit it to use as a microcontroller, but it can easily be expanded to have a 32-bit accumulator register, and 28-bit addressing using a hardware description language like Verilog or ...
Here is a simple example of index register use in assembly language pseudo-code that sums a 100 entry array of 4-byte words: Clear_accumulator Load_index 400,index2 //load 4*array size into index register 2 (index2) loop_start : Add_word_to_accumulator array_start,index2 //Add to AC the word at the address (array_start + index2) Branch_and_decrement_if_index_not_zero loop_start,4,index2 //loop ...