M782 Interrupt Control

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M7820 FLIP CHIP

The M782 Interrupt Control (later versions M7820 and M7821) is a DEC FLIP CHIP which implements the 'interrupt control' function for the UNIBUS.

It was used, along with an M105 Address Selector, in early PDP-11 device controllers which plugged into an SPC slot. It was also used in a number of early devices which were built out of a custom backplane and a large number of FLIP CHIPs, such as the RK11-C. Some later devices which no longer used a large number of small Flip Chips (such as the TMB11) also used it.

M7821 FLIP CHIP

The board contained a number of jumpers which could be use to set the interrupt vector. The M782 can set vector address bits 3-7 (i.e. vectors from 0 through 0374); bit 2 (04) is controlled be the device's electronics. The M7820 has more jumpers, on address bits 2-8 (i.e. vectors of the form 0xx0 and 0xx4); bit 2 (04) can be controlled be either the device's electronics, or the jumper.