PDP-11/05

Introduction

Introduced on June 1972, the PDP-11/05 and PDP-11/10 were small general purpose low cost UNIBUS minicomputers with limited expandability. They were ideal as embedded application controllers and most were used as such. Both 11/05 and 11/10 were fundamentally the same computers utilizing the KD-11B process implemented on two hex width cards; M7260 and M7261. As with later PDP-11 processors, the CPU's instruction set was implemented through ROM microcode. Initial versions of the 11/05 came in 5.25 inch high boxes with 9 slots. Later versions came in larger BA11-D and BA11-K mounting boxes. The 11/05/10 models featured the customary band of front panel switches similar to the other early models (11/20, 11/40, 11/45, etc.). The address space was 18 bits but only 16 bits were usable thereby limiting the memory to 32KB. An interesting feature of the KD-11B CPU was that the serial console (UART) was on the CPU board, interfaced with a 20mA Teletype and thus a separate serial controller card was not needed.

At one time I owned two 11/05s in the 5.25" small cabinet and purchased an 11/10 in the larger cabinet which was sold to a re-seller. I tried running RT-11 on one of the 11/05s with 8KW of memory but it was difficult to do anything with that memory and CPU combination and the systems were eventually sold. RT-11 5.X could barely run on this configuration. An interesting feature of the KD-11B CPU was that the serial console (UART) was on the CPU board, interfaced with a 20mA Teletype and thus a separate serial controller card was not needed.

The 11/05s were manufactured in Maynard (Massachusetts, USA), Galway (Ireland), Kanata (Ontario, Canada) and likely many other DEC manufacturing locations.

Backplane Configurations

There were four backplane configurations of the 11/05/10 computers. The initial systems were shipped with MM11-L 16Kbyte core memories. All backplanes were wire wrapped. Card locations below are from the point of view of the open card cage (insertion facing), where Row 1 is the uppermost row of the chassis.

Configuration 1

Row #	Row Slots A B	Row Slots C D E F
1	M7260 CPU Card 1
2	M7261 CPU Card 2
3	G110 Memory Controller
4	G231 Memory Driver
5	UNIBUS Terminator	H213 / H214 Core Memory Stack
6	G110 Memory Controller
7	G231 Memory Driver
8	UNIBUS OUT	H213 / H214 Core Memory Stack
9	KM11-1 \| KM11-2	SPC

Configuration 2

Row #	Row Slots A B	Row Slots C D E F
1	M7260 CPU Card 1
2	M7261 CPU Card 2
3	G110 Memory Controller
4	G231 Memory Driver
5	UNIBUS Terminator	H213 / H214 Core Memory Stack
6	UNUSED	SPC
7	UNIBUS OUT	SPC
8	KM11-1 \| KM11-2	SPC
9	DF11-1	SPC

Configuration 3 - as used on /05N and /10N processor models.

Row #	Row Slots A B	Row Slots C D E F
1	DF11-1	M9970 \| KM11-1 \| KM11-2
2	M7260 CPU Card 1
3	M7261 CPU Card 2
4	UNIBUS Terminator	H213 / H214 Core Memory Stack
5	G110 Memory Controller
6	G231 Memory Driver
7	G110 Memory Controller
8	G231 Memory Driver
9	UNIBUS OUT	H213 / H214 Core Memory Stack

Configuration 4 - as used on /05S and /10S processor models.

Row #	Row Slots A B	Row Slots C D E F
1	M7260 CPU Card 1
2	M7261 CPU Card 2
3	G110 Memory Controller
4	G231 Memory Driver
5	UNIBUS Terminator	SPC
6	G235 X-Y Core Drive
7	H217-D Core Stack
8	G114 Sense / Inhibit
9	UNIBUS OUT	M8293 Memory Controller