Abstract: An Undo/Redo feature for a graphical programming system which minimizes the required data storage. The graphical programming system includes a plurality of interconnected objects, including fixed size objects and variable size objects. A variable size object is an object which typically changes in size, i.e., grows or shrinks, in response to user modification, whereas fixed size objects do not change in size. When an object is modified by the user, the method of the present invention stores a backup copy for undo purposes. For modification of an object, the backup is performed differently depending on whether the object is a variable size object or a fixed size object. For a variable size object, the method stores the original object as the previous object in the backup list, and the method stores a copy of the original object as the current object in the backup list.

Abstract: A computer is provided having a bus interface unit between a CPU bus and a memory bus. The bus interface unit includes a memory controller and a read/write queue manager. The memory controller dispatches, or removes read requests or write requests from respective read or write requests queues depending on various modes of operation. Typically, the read requests are dispatched or removed either singularly or as a programmed series of read requests prioritized over write requests unless the write request queue is almost full. If the write request queue is almost full, then write request are removed either singularly or in a series before servicing the read request queue. The number of read or write request being removed from their respective queues can be programmed within a configuration register operably coupled to a controller arranged between the read and write request queues. The memory controller determines how many requests will be serviced within possibly a lengthy series of requests.

Abstract: A microprocessor having a microcode unit is provided. Routines comprising DSP functions and instruction emulation routines are stored within a read-only memory within the microcode unit. The routines may be fetched by the microprocessor upon occurrence of a corresponding instruction. For example, DSP functions may be fetched upon occurrence of an instruction defined by the microprocessor to be indicative of a DSP function. The microcode unit provides a library of useful functions. Effectively, the instruction set executed by the microprocessor is increased. A number of methods for defining instructions indicative of a DSP function are contemplated. For example, a subroutine call instruction having a target address within a predefined range of addresses may be defined as indicative of a DSP function. Alternatively, a special subroutine call instruction may be added to the instruction set.

Abstract: A computer system includes multiple local buses to which processors and other devices may be connected. A repeater is coupled to each of the local buses. Additionally, a top level repeater is coupled to each of the repeaters. The repeaters transmit transactions from the corresponding local buses to the top repeater. The top repeater, based upon the local or global nature of the transaction, transmits the transaction to one or more of the repeaters. The repeaters receiving the transaction then transmit the transaction upon the local buses attached thereto. If the transaction is a local transaction, the top repeater transmits the transaction to those repeaters which are configured into a local domain with the repeater which detected the initial transaction. The local domain comprises one or more repeaters which are logically interconnected. The local buses attached thereto logically form one SMP bus to which devices may be attached. Alternatively, the transaction may be a global transaction.

Abstract: A scanning system for scanning bar codes attached to wafer cassettes received in a chamber of a wafer processing tool. The system includes a scanner positioned external to the chamber for reading the bar codes and generating signals indicative thereof. Light generated by the scanner passes through an opening in the chamber wall and reflects off one or more reflective or refractive members positioned internal to the chamber, to illuminate the bar code attached to a wafer cassette contained in the chamber. Light reflected from the bar code likewise is bent by the reflective or refractive members and passes through the wall opening where it is sensed by the scanner. The reflective or refractive members are positioned so that the scanner can read bar codes which are not within the line of sight of the scanner through the wall opening.