Description:

VL82C331 ISA Bus Controller

The 160-lead VL82C331 ISA Bus Controller provides the functions of DMA, page address register, timer, interrupt control, port B logic, slot bus refresh address generation, and real-time clock. To avoid problems with sensitive slot bus add-in cards, the Bus Controller features "Bus Quiet" mode operation. when no valid slot bus accesses are occurring, none of the slot bus data, addresses, or control lines are driven. Built-in "Sleep" mode features work together with System Controller special features to provide a low-power system idle state for extension of battery life in portable, laptop, and hand-held systems. If an interrupt occurs due to an external source or dedicated, internal programmable timer, the Vus Controller "wakes up" and resumes normal operation. The DMA channels have been upgraded to provide a superset of AT functionality by allowing DMA to the entire 23M byte memory range. Additional functionality is provided via DMA wait state, clock and MEMR timing programmability.