Assembler Computer Organization and Architecture by admin - December 29, 2022January 1, 20230 Introduction Computer instructions are referenced from Instruction Types here for the purpose of reference. These are used by the assembler while translating the symbolic code to its binary code. Instructions were categorized as MRI Instructions : Direct or indirect memory reference instructions Non-MRI instructions: Instructions does not make a reference to memory, These are register reference or the I/O reference type of instructions. Category or Type of Programming languages Computer or specifically the processor understands and can execute the binary language programs only. Programs written in any other language must be translated to the machine or binary language. The programs may be developed using one of the following types of programming languages: Binary or machine level language: This is the computer natural programming language that
Addressing Modes Computer Organization and Architecture by admin - December 21, 2022December 21, 20220 Addressing Modes The instruction format for a general purpose computer was described in Instruction Types states that the OP-Code field specifies the operation to be performed, data is required to be supplied to ALU for this operation. Addressing Mode The way the data or the operands are chosen during the execution of a program depends on how the data is to be supplied since data may come from input devices, from memory or from registers etc. So, the addressing mode specifies the rule or the methods for interpreting the address fields of the instruction before the operand is actually referred. Purpose of the addressing modes: To give programming versatilities to the user by providing different ways of addressing or referencing to data such as naming variables,
Arithmatic Algorithms Computer Organization and Architecture by admin - June 1, 2021December 23, 20220 Binary Multiplication Binary multiplication is is explained using two approaches Using the simple binary multiplication Using the Binary 2's complement Booth's Multiplication Algorithm first we explain using the first approach Simple binary multiplication Fig: Binary multiplication Algo Example-1: Multiply 22 and 21 using binary multiplication algorithm explain figure above Multiplicand Register B = 22 = 10110 Multiplier Register Q = 21= 10101 Step Qn Operation Carry (E) Acc (A) Multiplier (Q) Count initialize x x 0 00000 10101 5 1, 1, A=A+B 00000 10110 --------- 10110 Shr EAQ 0 01011 01010 4 2 0 Shr EAQ 0 00101 10101 3 3 1 Add 0 00101 10110 -------- 11011 Shr EAQ 0 01101 11010 2 4 0 Shr EAQ 0 00110 11101 1 5 1 Add 0 00110 10110 -------- 11100 Shr EAQ 0 01110 01110 0 ANSWER 22 x 21 = 462 = 00111001110 Example-2 : Multiply 30 and 26 using Binary Multiplication Algorithm Multiplicand Register B = 30 = 11110 Multiplier Register Q = 26= 11010 Step Qn Operation Carry (E) Acc (A) Multiplier (Q) Count initialize x x 0 00000 11010 5 1, 0 Shr EAQ 0 00000 01101 4 2 1 Add A, B 0 00000 11110 -------- 11110 Shr EAQ 0 01111 00110 3 3 0 Shr EAQ 0 00111 10011 2 4 1 Add 1 00111 11110 -------- 00101 10011 Shr EAQ 0 10010 11001 1 5 1 Add 1 10010 11110 --------- 10000 0 Shr EAQ 0 11000 01100 0 ANSWER 30x26 = 780 = 01100001100 2’sComplement Multiplication Booth’s Algorithm Example multiply -12 x -20 using Booth's Algorithm Let multiplicand = -20 ; Reg B(-
Microprogrammed Control Unit Computer Organization and Architecture by admin - May 19, 2021December 19, 20220 Microprogram Control Unit As discussed in Control Unit topic, a control unit generates a binary control variable for executing a particular microoperations. The control unit can be a hardwired or microprogrammed control unit. A control word can be programmed to perform various operations on components of the system. A control unit whose control word is stored in the control memory which is usually a ROM is called as microprogram control unit. Each control word in the control memory contains within it a microinstruction. Every microinstruction specifies one or more micro-operations. A microprogram is written for every instruction supported by the CPU. Each instruction of a program causes the corresponding micro-program to be fetched and its control information extracted in a manner that resembles the
Control Unit Computer Organization and Architecture by admin - May 17, 2021December 18, 20220 Introduction A general purpose computer consist of Input-output units, processing unit and a memory unit. Input-output permits interaction with the physical world whereas the memory unit stores user program and the binary information. The functional part of a general purpose digital computer, its functional units, the interaction between the control and the processor and the types of the control logic. Figure-1 on top left shows the function parts of a general purpose digital computer as CPU, input-output devices and the memory unit. Functional unit of a CPU is shown in figure 2 top right as ALU, set of registers and the timing and the control logic. Basic Function of the control logic : to generate timing sequences. to take input from the external sources and