# Binary adder and subtractor

A binary full adder-subtractor as defined in claim 1 wherein one of said first or second binary bit signals is designed as a minuend and the other as a subtrahend and further comprising mode control means coupled to said carry or borrow logic chain and responsive to a subtract control signal to cause said adder-subtractor to subtract said subtrahend bit signal from said minuend bit signal to produce the difference bit signal as said output bit signal. Furthermore, in those cases binary adder and subtractor the division is done in a matrix, the inclusion of matrix elements to handle the corrective additions doubles the size of the required matrix. A Y signal at input 32 is, therefore, equivalent to the instruction, Yes, do not subtract. Radix divider using overlapped quotient bit selection and concurrent quotient rounding and correction. Cj In the expression of the sum Cj must be generated by the full binary adder and subtractor at lower position j.

Retrieved from " https: In other words, the information at the P terminals of the row must be repeated at the T terminals binary adder and subtractor that row, and the borrow conditions if the E and F inputs of that row are used must be maintained. This constitutes a Y signal which is impressed through diode 61 as the suppress or control input of buffer 14 of FIG.

K or not add; S or no subtract; and K or bypass. The control gate of this suppressor has an N signal from the K control input 16. The logic of this operation is as follows.

The buffer B of FIG. A full binary subtracter must satisfy the following truth table: Adders are a part of the core of an arithmetic logic unit ALU. Radix divider using overlapped quotient bit selection and concurrent quotient rounding and correction.

Many prior art full binary adders binary adder and subtractor subtracters are known. A further object is to provide an improved semiconductor arithmetic unit having add-subtract control and function bypass control. For large values of N, the delay becomes unacceptably large so that a special solution needs to be adopted to accelerate the calculation of the carry bits.

A further object is to provide an improved binary arithmetic unit which can be controlled to perform either addition or subtraction. In similar fashion, a carry in on point 19, coupled with a sum 1 on line 40 operating through the AND gate of resistors 82, 83 and 81 and through transistor 80 will suppress any sum signals passing through OR gate complex of diodes 94 and A Y signal at input 32 is, therefore, equivalent binary adder and subtractor the instruction, Yes, do not subtract.

It can also be seen that, depending on the cur-rent handling capability of the output buffer, the output signal from this stage could binary adder and subtractor used directly, without need for itemsandas the K control signal for all of the second row units including the nth unit. The values of the resistors and the bias potential V, are so chosen that a positive Y signal on either the P input 10 or the E input 11, but not on both, will leave point at a potential below that slight positive with respect to ground potential required at the base of transistor 51 to cause conduction in transistor The design of the look-ahead carry generator involves two Boolean functions named Generate and Binary adder and subtractor. Radix divider using overlapped quotient bit selection and concurrent quotient rounding and correction. The function is such that a Binary adder and subtractor signal at input 32 operating through diode 57 as the control input effectively clamps point at ground, creating an N signal regardless of the signal impressed on line 41 or

Furthermore, in performing division, it must be capable of subtracting one or two bits from zero or one and producing the proper difference and borrow signals. Continuing this one step further, by substituting 1s and zeros for binary adder and subtractor signals or no signals respectively, one can summarize the add operations to the eight possibilities shown in truth table number 1. For large values of N, the delay becomes unacceptably large so that a special solution needs to be adopted to accelerate the calculation of the carry bits. It is to be noted that in the event that there are two Y signals present at P and E inputs or present at the F input and on line binary adder and subtractor due to only one signal on either the P or E input then the buffers 51 or 80 are acting in binary adder and subtractor manner as to suppress the generation of either an erroneous borrow signal or an erroneous sum signal. In FIGURE 3b, the G output terminal G of the highest order or nth stage of the second row is con nected to one input of AND gateand an array control signal is applied to the other input for performing division or root extracting.

These two f inputs combine to produce a Y signal in the output Lme 39 Y of OR gate 33, which is impressed as an in ut to butter Lme 40 N 35, resulting in a Y signal output from buffer 35 which Lme 41 N 25 appears on line 47 and thence on output terminal 38, Input 19 Y which is the sum or difference output of the add-subtract Resuming the description from this point, it can be seen f yi the slgnal 0n 'llne a d he Y that the Y signal at input 19 and the N signal on line slgnal 4 46, an? A description of the function of the K control requires reference again to FIG. Floating-point processor having pre-adjusted exponent bias for multiplication and division. Furthermore, since the output correction is in direct response to binary adder and subtractor input change, the binary adder and subtractor flow is along a most eflicient path.