摘要:
A multilevel set associative cache system whose directory and cache store are organized into levels of memory locations includes control apparatus which selectively degrades cache operation in response to error signals from directory error checking circuits to those levels detected to be free from errors. Test apparatus coupled to the control apparatus and operates to selectively alter the operational states of the cache levels in response to commands received from a central processing unit for enabling testing of such control apparatus in addition to the other cache control areas.
摘要:
A multilevel set associative cache system whose directory and cache store organized into levels of memory locations. Round robin replacement apparatus is used to identify in which level information is to be replaced. The directory includes error checking apparatus for generating address check bits which are written into directory locations together with addresses. Control apparatus in response to error signals from the error checking apparatus degrades cache operation to those levels detected to be free from errors. Test error mode control apparatus which couples to the replacement and check bit apparatuses causes the address check bits to be selectively forced to incorrect values in response to commands received from a central processing unit enabling the verification of both the checking and control apparatus without interference from other operations initiated by the central processing unit.
摘要:
A microprogrammed commercial instruction processor in a data processing system includes a bank of switches coupled to a multitapped delay line for selecting delay line signals for setting the basic clock timing. Another of the switches when activated conditions the commercial instruction processor so that when it is reset a special clock setting firmware loop is entered. The loop provides an uninterrupted succession of clock pulses which allows one to adjust the basic clock timing within specification.
摘要:
A data processing system includes a commercial instruction processor (CIP) for executing decimal arithmetic instructions. The operands processed by the CIP include packed decimal and string decimal operands. The decimal arithmetic instruction includes descriptors for describing the characteristics of the operands. A register coupled to an arithmetic logic unit stores double words of the operands which are written into the register as double words, bytes or decimal digits. A multiplexer is responsive to control store signals and descriptor signals for generating write control signals which are applied to a read only memory. The read only memory output write signals select the decimal digit, byte or double word positions of the register for writing.
摘要:
A data processing system having a control store storing firmware words for controlling the system, logic for executing logical operations on input data, including the performing of a first and second data processing routine, and apparatus for addressing the control store to access selected firmware words to control the execution of desired logical operations on the input data. The system operates in a particular mode of control to suspend the operation of the first routine in order to execute the second routine whereby the logical apparatus includes a register for saving a return address associated with the last instruction of the first routine. When the system terminates the second routine and restores the first routine to operation, the contents of the save register are employed, with the lowest order bit thereof inverted, to access the control store to fetch the firmware word used to reenter the first routine.
摘要:
A control store having a first portion for storing system operation instructions (opcodes), a second portion for storing control store addressing information, wherein the second portion includes a greater number of storage locations than does the first portion in order to efficiently store different control store address information which may be required for the same opcode. Addressing apparatus coupled to address a location in the first portion and any one of at least two corresponding locations in the second portion is provided, thereby minimizing the number of locations required in the first portion of the control store.