Abstract: A device for connecting 8-bit and 16-bit modules to a 16-bit microprocessor. Primary data inputs and outputs of the 16-bit microprocessor are coupled, through data buffers, to the information inputs and outputs of half of the 8-bit modules and to primary data inputs and outputs, respectively, of the 16-bit modules, while secondary data inputs and outputs of the 16-bit microprocessor are coupled, through data buffers, to the information inputs and outputs of the other half of the 8-bit modules and to the secondary data inputs and outputs, respectively, of the 16-bit modules. On operations requiring word, or two-byte, exchange operation with the 8-bit modules, a control circuit extends operation of the 16-bit microprocessor allowing the 8-bit modules to work on the two-byte word one byte at a time. The 16-bit modules are capable of word exchange with the 16-bit microprocessor by simultaneously using the primary and secondary inputs and outputs thereof.

Abstract: A method and apparatus for connecting a 16 bit microprocessor to an 8-bit device such as a memory device permits full 16-bit (2-byte) words to be exchanged to or from the 16-bit microprocessor through a series of buffers controlled by a control circuit which is driven by the microprocessor. The method and apparatus puts the microprocessor in a wait state with strictly defined duration when reading a first byte from an 8-bit device, a control circuit stores it in a buffer register, modifies the read address of the 8-bit device, and then sends the stored first byte together with a second byte read from the 8-bit device to the microprocessor simultaneously. This arrangement makes the 8-bit device appear like a 16-bit device to the microprocessor. When writing to the 8-bit device, two bytes are simultaneously taken from the microprocessor, one going directly to the 8-bit device and the other going to a buffer.