When.com Web Search

Search results

  1. Results From The WOW.Com Content Network
  2. Simplified Instructional Computer - Wikipedia

    en.wikipedia.org/wiki/Simplified_Instructional...

    Format 4: Only valid on SIC/XE machines, consists of the same elements as format 3, but instead of a 12-bit displacement, stores a 20-bit address. Both format 3 and format 4 have six-bit flag values in them, consisting of the following flag bits: n: Indirect addressing flag; i: Immediate addressing flag; x: Indexed addressing flag

  3. Addressing mode - Wikipedia

    en.wikipedia.org/wiki/Addressing_mode

    An addressing mode specifies how to calculate the effective memory address of an operand by using information held in registers and/or constants contained within a machine instruction or elsewhere. In computer programming, addressing modes are primarily of interest to those who write in assembly languages and to compiler writers.

  4. Instruction set architecture - Wikipedia

    en.wikipedia.org/wiki/Instruction_set_architecture

    However, more typical, or frequent, "CISC" instructions merely combine a basic ALU operation, such as "add", with the access of one or more operands in memory (using addressing modes such as direct, indirect, indexed, etc.). Certain architectures may allow two or three operands (including the result) directly in memory or may be able to perform ...

  5. Comparison of instruction set architectures - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_instruction...

    Architectures typically allow instructions to include some combination of operand addressing modes: Direct The instruction specifies a complete address Immediate The instruction specifies a value rather than an address Indexed The instruction specifies a register to use as an index. In some architecture the index is scaled by the operand length ...

  6. Orthogonal instruction set - Wikipedia

    en.wikipedia.org/wiki/Orthogonal_instruction_set

    In contrast to the PDP-11's 3-bit fields, the VAX-11's 4-bit sub-bytes resulted in 16 addressing modes (0–15). However, addressing modes 0–3 were "short immediate" for immediate data of 6 bits or less (the 2 low-order bits of the addressing mode being the 2 high-order bits of the immediate data, when prepended to the remaining 4 bits in ...

  7. PDP-11 architecture - Wikipedia

    en.wikipedia.org/wiki/PDP-11_architecture

    PDP-11 processor speed varies by model, memory configuration, op code, and addressing modes. Instruction timings have up to three components, fetch/execute of the instruction itself and access time for the source and the destination. The last two components depend on the addressing mode.

  8. Reduced instruction set computer - Wikipedia

    en.wikipedia.org/wiki/Reduced_instruction_set...

    The CDC 6600 designed by Seymour Cray in 1964 used a load–store architecture with only two addressing modes (register+register, and register+immediate constant) and 74 operation codes, with the basic clock cycle being 10 times faster than the memory access time. [11]

  9. Memory-mapped I/O and port-mapped I/O - Wikipedia

    en.wikipedia.org/wiki/Memory-mapped_I/O_and_port...

    Memory-mapped I/O is preferred in IA-32 and x86-64 based architectures because the instructions that perform port-based I/O are limited to one register: EAX, AX, and AL are the only registers that data can be moved into or out of, and either a byte-sized immediate value in the instruction or a value in register DX determines which port is the source or destination port of the transfer.