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Which bit of flag register is used for controlling the si and di?
Wiki User
∙ 12y ago
The direction flag (DF) is used to control the use and direction of repeated string operations involving DI and SI.
Wiki User
∙ 12y ago
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Flag registers in Pentium 2 microprpcessor?
list 8-bit register that are used for register addressing
How many flag registers are there in 8085?
We have only one flag register of 8 bits. Bits description is as follows (Assuming D0=LSB & D7=MSB) D7=Sign Bit. D6= Zero Flag D4= Auxiliary Carry Flag D2 = Parity Flag D0= Carry Flag.
How many registers are there in an 8085 microprocessor?
Accumulator or A register is an 8-bit register used for arithmetic, logic, I/O and load/store operations. Flag is an 8-bit register containing 5 1-bit flags: * Sign - set if the most significant bit of the result is set. * Zero - set if the result is zero. * Auxiliary carry - set if there was a carry out from bit 3 to bit 4 of the result. * Parity - set if the parity (the number of set bits in the result) is even. * Carry - set if there was a carry during addition, or borrow during subtraction/comparison. General registers: * 8-bit B and 8-bit C registers can be used as one 16-bit BC register pair. When used as a pair the C register contains low-order byte. Some instructions may use BC register as a data pointer. * 8-bit D and 8-bit E registers can be used as one 16-bit DE register pair. When used as a pair the E register contains low-order byte. Some instructions may use DE register as a data pointer. * 8-bit H and 8-bit L registers can be used as one 16-bit HL register pair. When used as a pair the L register contains low-order byte. HL register usually contains a data pointer used to reference memory addresses. Stack pointer is a 16 bit register. This register is always incremented/decremented by 2. Program counter is a 16-bit register.
Carry flag and over flow flag in 8051?
Carry flag is the the bit 7 of the 8 bit PSW register, whenever there is an addition or subtraction process that has a carry on its 7th bit, the carry flag (C/CY) will be set to 1. OV is set to 1 when there is an arithmetic overflow. this applies to signed and unsigned operations.
Why does 8085 microprocessor has 8 bit flag register when it has only 5 flags?
The 8085 microprocessor has an 8-bit flag register, even though it only has 5 flags, because all of the registers in the 8085 are 8-bit or 16-bit. In fact, the flags register is considered to be part of the accumulator, as one "register pair", for purposes of stack push/pop and interrupt call/return. Be warned, however, that you should not attempt to change the state of bits stored on the stack and then pop'ing them into AF, because some of the three "unused" bits might be undocumented but actually used, or their meaning might change between different versions of the chip.
Explain 8086 flag register?
FLAGS REGISTER="h2headingh3"style="color:rgb(0,0,0);"name="flags_register">Flags Register - determines the current state of the processor. They are modified automatically by CPU after mathematical operations and allow one to determine the type of the result as well as determine conditions to transfer control to other parts of the program. Generally you cannot access these registers directly.Carry Flag (CF) - this flag is set to 1 when there is an unsigned overflow. For example when you add bytes 255 + 1 (result is not in range 0...255). When there is no overflow this flag is set to 0.Parity Flag (PF) - this flag is set to 1 when there is even number of one bits in result, and to 0 when there is odd number of one bits.Auxiliary Flag (AF) - set to 1 when there is an unsigned overflow for low nibble (4 bits).Zero Flag (ZF) - set to 1 when result is zero. For non-zero result this flag is set to 0.Sign Flag (SF) - set to 1 when result is negative. When result is positive it is set to 0. (This flag takes the value of the most significant bit.)Trap Flag (TF) - Used for on-chip debugging.Interrupt enable Flag (IF) - when this flag is set to 1 CPU reacts to interrupts from external devices.Direction Flag (DF) - this flag is used by some instructions to process data chains, when this flag is set to 0 - the processing is done forward, when this flag is set to 1 the processing is done backward.Overflow Flag (OF) - set to 1 when there is a signed overflow. For example, when you add bytes 100 + 50 (result is not in range -128...127).
Show the bit positions of various flags in 8085 flag register?
The 8085 microprocessor has 5 flags: 1. Zero flag: The zero flag is set, when the ALU operation results a zero . 2. Carry flag: If an arithmetic operations results in a carry, this flag is set. 3. Parity flag: This flag is set, when an arithmetic or logical operation results in a data, which has even number of 1s. If otherwise, it is reset. 4. Sign flag: After the execution of an arithmetic or logic operations, if D7 bit of the accumulator is 1, it indicates a negative number and this flag is set. If otherwise, it is reset. 5. Auxiliary Carry flag: used for BCD Operations, During the BCD operations, if D3 bit producing the carry then the AC bit set as1, otherwise the bit is 0. 6. Carry Flag: when a carry is generated by digit D7, then the carry flag set as 1, otherwise the bit will be 0.
Give the steps to set trap flag to 1?
;assuming trap flag is the 8th bit in the flags register pushf pop ax or ax,0100h push,ax popf
What is the size of flag register?
All of the 8086/8088 registers, AX, BX, CX, DX, SP, BP, SI, DI, CS, DS, SS, ES, IP, and FLAGS, are 16 bit registers. The AX, BX, CX, and DX registers may also be viewed as 8 eight bit registers AH/AL, BH/BL, CH/CL, and DH/DL.
What is overflow bit in register?
In Computerprocessors, the overflow flag (sometimes called Vflag) is usually a single Bitin a system Status_registerused to indicate when an Arithmetic_overflowhas occurred in an operation.
What is the purpose of DI register in microprocessor in 8086?
DI is the Index register in Data segment(16-bit, 64 KB) .Destination Index (DI) is a 16-bit register. DI is used for indexed, based indexed and register indirect addressing, as well as a destination data address in string manipulation instructions.
Definition or function of CX register?
The CX register is a 16-bit register in the x86 architecture that is primarily used for counting operations, particularly in string manipulation and looping functions. It is part of the general-purpose registers in the CPU and can store values ranging from 0 to 65,535.
