Abstract: A peripheral device controller has an EEPROM which stores microinstructions to be placed in a random access memory control store. The EEPROM also stores peripheral configuration information. This information is obtained by polling the peripheral devices connected to the controller and storing the resulting information in the EEPROM. Upon powering up, the microinstructions stored in the EEPROM are transferred to the control store via execution of instructions held in a boot PROM. The controller, therefore, provides a fast control store while maintaining permanence of the microinstructions after power is extinguished. Means are also provided to update the control store and EEPROM. The EEPROM may upon CPU command be updated with new microinstructions held in main memory or obtained from peripheral devices.

Abstract: A controller connected between a system bus and peripheral devices has at least two microprocessors. One controls the data transfers with the peripheral devices, and the other controls data transfers with the system bus. The microprocessors share a data buffer and control store. This sharing is possible because of the controller timing means which synchronizes exclusive access to the shared components of the controller. When first initialized, the microprocessors are directed to execute a test instruction which points them to the beginning of their set of microinstructions. Once pointed to their set of microinstructions, normal operation may begin.

Abstract: A controller controls data transfers between a data processing system bus and peripheral devices. In the controller, data buffers are divided into page frames. Paging circuitry provides for allocation and deallocation of pages to and from the data buffer. Included in the page circuitry is a paging RAM. The paging RAM and other paging circuitry components allow contiguously addressed pages of data to be stored in noncontiguous locations in the data buffer. There may be more than one data buffer and these data buffers may be exclusively seized by microprocessors in the controller via seizing logic.