Abstract: A data processing apparatus includes a three input arithmetic logic unit (230) that generates a combination of the three inputs that is selected by a function signal. Data registers (200) store the three data inputs and the arithmetic logic unit output. The second input signal comes from a controllable barrel rotator (235). The rotate amount is a default rotate amount stored in a special data register, a predetermined set of bits of data recalled from a data register or zero. A one's constant source (236) is connected to the barrel rotator (235) to supply a multibit digital signal of "1". This permits generating a second input signal of the form 2.sup.N, with N being the rotate amount. The output of the barrel rotator (235) may be stored independently of the arithmetic logic unit (230) result. A controllable shifter is an alternative to the barrel rotator (235).

Abstract: Data processor with a transparency detection data transfer controller. Transparency register stores transparency data. Source address controller calculates source addresses for recall of data to be transferred. A comparator compares recalled data to stored transparency data and indicates whether data to be transferred is to be written to memory. Destination address controller writes data to be transferred into memory at calculated destination addresses if the comparator indicates data to be transferred is to be written to memory. The recalled data is stored in a source register for comparison. In the preferred embodiment data is not written into memory if it matches the transparency data. The transparency register may store a multiple of the minimum amount of data to be transferred. The data to be transferred is organized into data words having a selected size. This selected size is an integral multiple of a minimum amount of data to be transferred.

Abstract: A data processor with a transparency detection data transfer controller transfers data from a block of source addresses to a block of destination addresses. A transparency register stores transparency data. A comparator compares the recalled data to the stored transparency data and indicates whether the data to be transferred is to be written to the memory. The recalled data to be transferred is not to be written into the memory if it matches the transparency data. The transparency register may store a multiple of a multibit minimum amount of data to be transferred. The data to be transferred has a selected size which is an integral multiple of a minimum amount of data to be transferred. The comparator includes plural data comparators corresponding to each multibit minimum amount of data to be transferred.