James Leslie Tietjen

US Patent:

46334378, Dec 30, 1986

Filed:

Jun 26, 1984

Appl. No.:

6/624660

Inventors:

David S. Mothersole - Austin TX
Lester M. Crudele - Groton MA
James L. Tietjen - Austin TX
Robert R. Thompson - Austin TX

Assignee:

Motorola, Inc. - Schaumburg IL

International Classification:

G06F 900

US Classification:

364900

Abstract:

In a data processor adapted to perform operations upon operands of a given size, a bus controller is provided to communicate the operands with a storage device having a data port which may be a submultiple of the operand size. In response to a signal from the bus controller requesting the transfer of an operand of a particular size, the storage device provides a size signal indicating the size of the data port available to accommodate the requested transfer. Depending upon the size of the operand to be transferred and the size of the data port of the storage device, the bus controller may break the operand transfer cycle into several bus cycles in order to completely transfer the operand. In the process, the bus controller compensates for any address misalignment between the operand and the data port. In order to distinguish individual operand cycles from the several bus cycles which may comprise the operand cycle, the bus controller provides an operand cycle start signal only at the start of the first bus cycle of each operand cycle.