| 摘要 |
PURPOSE:To set variably the number of buses to be used among any devices and to optimize a system data transfer speed by mounting an expansion bus in parallel to a data bus and recognizing mutually the setting number of the expansion buses among respective devices through the data bus. CONSTITUTION:When a device B is requested for data transferring/receiving by a device A, if the device A side possesses a transferring/receiving buffer 2, a message 'the expansion bus has been used' is indicated on the bus bit length of a sending command row and transferred through a data bus 5. When the device B possesses a transferring/receiving buffer 4, the device B carries out the following data transferring/receiving operation using both the data bus and the expansion bus 6 at the same time. When not the transferring/ receiving buffer 4, said device B does not carry out the following data transferring/receiving operation, but indicates 'expansion bus does not exist' on the bus bit length of the sending status and also indicates 'data transferring/ receiving is impossible' on the terminal information. When the device A recognizes this indication, said device A indicates 'expansion bus 6 has been not used' on the bus bit length of sending command and restarts transferring using only the data bus 5. |
