Specifications

Processor Description (V40)
Loop Counter
LC
LC is a binary counter used to regulate iterative operations such
as string transfers controlled by the repeat prefix and multiple-bit
shifts and rotations. The CPU uses hardware for a loop counter,
as opposed to microcode used by the traditional microprocessor.
Temporary Registers A, B, and C
TA, TB, and TC
These 16-bit registers are used by the ALU during arithmetic and
logical instructions such as multiplication, division, and shift and
rotate. TA and TB combine for 32-bit temporary storage during
multiplication and division. Access to the temporary registers is
not available to the programmer.
Arithmetic and Logic Unit
ALU
The ALU performs arithmetic and logic operations as well as bit
manipulation. Arithmetic and logic operations include add,
subtract, multiply, divide, increment, decrement, compare,
complement, AND, OR, and exclusive OR. Bit manipulation
includes shifting, rotating, comparing, setting, clearing, and
inverting of individual bits.
Effective Address Generator
EAG
The 16-bit offset address calculated by the EXU for memory
operations is called the effective address. The effective address
can include a displacement, base, index, or combination of the
three, depending on the addressing mode specified in the
instruction being executed. Traditional microprocessors calculate
this effective address using microcode. The EAG does this
calculation in hardware. As an example, the 8088 requires up to
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