Microverter- Unibus to Qbus conversion for PDP to LSI-11 migration

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PDP-11 migration with
MICROVERTER ^TM

Millions of dollars have been spent on software applications that ran on PDP-11 computers under various operating systems. Now that the PDP-11 series is no longer in production, the cost of maintenance is growing at a phenomenal rate. Many applications were dependent upon interfaces that were only available on the Unibus with no equivalent on the Q-bus.

PROBLEM: Desire to move to LSI-11 Q-bus system, but software isn't compatible since the LSI-11 doesn't support I/O mapping and doesn't have a way to connect specialized Unibus controllers.

SOLUTION: The ABLE Microverter allows the connection of up to 19 Unibus devices (loads) to the Q-bus of any LSI-11. Not only does the Microverter perform a Q-bus to Unibus translation, it provides for the full emulation of the PDP-11 I/O mapping registers to maintain software compatibility on an LSI-11.

ABLE offers two solutions to the problem:

In the solution above, the choice is made to use a small Unibus Expansion chassis for the Unibus devices desired and to obtain a complete LSI-11 system in its own chassis. This is a somewhat more expensive way to go, but it has the benefits of being a smaller finished system using more modern appearance chassis.

The other choice, is to keep everything the same and merely replace the processor backplane in the existing PDP-11 chassis. In this approach, ABLE has a special backplane and accessories to allow the customer to just install a LSI-11 processor and Q-bus memory if desired.

There are a total of nine dual width Q-bus slots which allows for mixed dual & quad board arrangements. The processor is installed beginning with slots " a b" and continue from there in a serpentine arrangement. a -f , f -a , a -f , to the Microverter. empty slots must have bus grants jumpered or Q-bus grant boards installed. The regulator/console board drops the 15 volt PDP-11 voltages down to the 12 volt requirements for the Q-bus. The Microverter when purchased in the Microverter Plus Package includes the short Unibus Cable, Backplane and Regulator/console board.

There are thousands of ABLE bus converters in the field extending the life of PDP and early VAX applications.

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