Apparatus for data transfer between image memory and external I/O device wherein inner registers set the image valid area, direction and mode of transfer

摘要

In an image input/output control apparatus having three lines of n-bit bidirectional data buses provided on an external apparatus connection side of the apparatus and four lines of n-bit bidirectional data buses provided on an image memory side of the apparatus, there are provided a first inner register for setting the data transfer direction of each of the bidirectional data buses and a second inner register for setting an image valid area, whereby the data transfer direction of each of the bidirectional data buses is determined by a set point of the first inner register and the image valid area is determined by a set point of the second inner register.