KE11-A Extended Arithmetic Element

The KE11-A Extended Arithmetic Element is an autonomous UNIBUS peripheral which can perform a variety of arithmetic or logical operations:

• multiplication
• division
• multi-bit shifts
  • logical shift
  • arithmetic shift
  • normalization

(The last is used for implementation of floating point in software.)

It is implemented as several quad and dual boards, plugged into a custom four-slot system unit (details below).

The KE11-A was originally produced for use with the PDP-11/20, whose KA11 CPU did not have multiply, divide, or multi-bit shift operations. As a UNIBUS peripheral, not integrated into the CPU, it was also usable with other models, e.g. the PDP-11/05 and PDP-11/04, which likewise did not implement multiplication in hardware, etc.

The KE11-A can be operated with an optional KM11-A Maintenance Set in order to diagnose faults.

It was replaced by the KE11-B Extended Arithmetic Element, a program compatible re-implementation on a single hex card.

Hardware

The KE11-A consists of 3 quad boards:

• M7210 Data Control
• M7211 Register Control
• M827 Clock and States

and a pair of M234 Register dual-height boards, plugged into the quad custom backplane.

Board locations

These are the board locations for the KE11-A (as seen from the board side of the backplane):

	Connector
Slot	A	B	C	D	E	F
1	UNIBUS In		M7210 Data Control
2	Unused	KM11-A	M234 Register (low byte)		M234 Register (high byte)
3	G772 Power	Reserved	M7211 Register Control
4	UNIBUS Out		M827 Clock & States