摘要:
A system for issuing a family of instructions during a single clock includes a decoder for decoding the family of instructions and logic, responsive to the decode result, for determining whether resource conflicts would occur if the family were issued during one clock. If no resource conflicts occur, an execution unit executes the family regardless of whether dependencies among the instructions in the family exist.
摘要:
The present invention includes a suboperation code control memory which stores data for generating a heading address of a microprogram for an instruction having a suboperation code. Access to an operation code control memory by the ordinary operation code and the access to suboperation code control memory are carried out simultaneously. The heading address of the microprogram is generated by editing the data read from the respective control memories. The storage capacity needed for the suboperation memory is reduced and still no problem occurs in assigning microinstruction addresses, and the heading address of a microprogram for the instruction having a relevant suboperation code is produced without any additional time.
摘要:
A microprocessor with a multiplexer having its output coupled to the input of the instruction register for storing instructions to be executed and applying the bits of the instruction as the input signals to a mapping PLA. The inputs of the multiplexer are the information bus coupled to external pins to receive instructions either from external memory or from an external console, and the output of the ALU. The path from the output of the ALU to the input of the instruction register allows better self testing of the processor by iteself and self-generation of input/output instructions. This structure simplifies the processor by allowing console requests, instructions from memory and self generated instructions all to be stored in the same register, i.e., the instruction register, thereby eliminating the need for separate registers for each type of instruction. Further, this structure simplifies programming of repetitive I/O instructions for polling large numbers of I/O devices having sequential addresses in memory mapped I/O applications. That is, the microprocessor has the capability of generating its own I/O instructions from an operand coming in from memory such as by adding it to the contents of an index register and supplying the result to the instruction register through the ALU output, the ALU bus, and the multiplexer as the address of the particular I/O device to read from or write to.
摘要:
A microprogram control system of the invention has a mapping read only memory storing the respective initial addresses of a plurality of microprogram routines corresponding to a macroinstruction. The address input information to this mapping read only memory is obtained from an output of a binary counter which counts every time a JUMP instruction for making a branch to another microprogram routine is decoded, and from an output of a latch circuit for holding the operation code of the macroinstruction. When the microprogram routine has loops, a count inhibit signal is input to the binary counter so that the same address input information may be supplied to the mapping read only memory.
摘要:
A central processing unit of a computer system comprises a programmable logic array which is constructed of an AND matrix and an OR matrix. The AND matrix is responsive to a machine language instruction and to a number of a region for selecting one row from a plurality of rows arranged in the AND matrix. The OR matrix, which also has a plurality of rows, is responsive to the selected row for selecting one row therefrom. In each of the rows of the OR matrix a microaddress and a number of a region to be used for producing a subsequent microaddress are prewritten so that information on a microaddress and information on a region number are respectively obtained. At least one microinstruction included in a microprogram will be read out from a read-only memory in accordance with the obtained microaddress to execute the same, while a microaddress of a subsequent microprogram is produced in the programmable logic array. Namely the execution of a microprogram routine and the production of the first address of a following microprogram routine are concurrently performed so that efficient execution of microprograms can be achieved, while each microinstruction is not required to include region number information.
摘要:
A circuit outputs different subsidiary address data depending on operand address data contained within operand designation fields and operation codes of system instructions. A control storage, which stores microinstructions, is accessed for the initial microinstructions, contained within microinstruction sequences for system instructions, at storage locations specified by the operation codes and the subsidiary address data. As a result, different microinstruction sequences for system instructions with the same operation code can be initiated depending on the operand address data, without using any microinstructions for testing the operand address data.
摘要:
A microprogrammed computer comprises an instruction register for registering a machine instruction word; a decode read only memory (DROM) for storing the start address data of microprogram routines which correspond to machine instruction words, respectively, and the control bit data which correspond to the machine instruction words, respectively; and a read only memory (ROM) for storing a plurality of microprograms each consisting of microinstructions. The microprogrammed computer has such a hardware structure that each control bit datum in the DROM may serve to change the function of a microinstruction and the execution sequence of the microprograms in the ROM.
摘要:
A program control unit for a digital data processing installation is described. The program control delivers macrocommands from a macro-command memory, and micro-commands from a micro-command memory. The micro-commands can be delivered singly or in selected combinations. In addition to the main commands in the macro-command memory which act as macro-commands for directly releasing micro-programs, there are also main commands which follow each other and indirectly cause the delivery of one or more micro-commands. Indirect delivery of micro-commands is caused in any case by a machine address of a memory cell, belonging to the pertinent main command, related to the macrocommand memory for another macro-command. At least one auxiliary command which can be called up by different main commands is contained in a memory cell of this type. Each auxiliary command determines, by means of a micro-command machine address related thereto of the memory cell in the micro-command memory, the delivery of this micro-command or the delivery of this microcommand and the micro-command which follows in the micro-command memory.
摘要:
A microprogram branch technique is provided whereby the present microaddress for a read-only memory (ROM) is conditionally modified by selectable bit insertions corresponding to branch conditions. This provides a new microaddress containing a microinstruction for performing an operation corresponding to the branch conditions which cause this address. Two basic cases are considered, one where various types of addressing are controlled such as: indirect, indexed, or void address; the other where multiconditioned arithmetic control, such as may occur in multiplication or division, is translated into microbranches to expedite the operation execution and to minimize the number of microinstructions required.