JPS54136143A - Input/output circuit connection system for computer - Google Patents

Abstract

PURPOSE:To secure the switching connection between CPU's of different types with an extremely simple constitution by providing the means to contribute to the data switching partially to the outside of the plug-in. CONSTITUTION:When the word is designated by word byte designation signal 9, control circuit 2 delivers the data of upper- and lower-rank data register 3 and 4 to data bus 11 at one time via bus driver 7 and with the upper- and lower-rank byte designation signals 12 and 13 set to logic ''1''. Then in case plug-in 1 is used to the byte machine, data bus 11 connects the bits corresponding to the upper and lower-rank bytes to the outside of plug-in 1 as shown by the dotted lines. In this case, only data buses DB0-DB7 are used for the connection to CPU. With designation of the byte by signal 9, circuit 2 sets signal 12 and 13 to logic ''1'' in the upper and lower ranks each via upper-/lower-rank byte designation signal 10. Then the upper- and lower-rank byte data are delivered to data bus 11 respectively.