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DEC PDP-11/70

DEC PDP-11/70

This PDP 11/70 was donated to the RICM by Steve Hort of Mount Vernon, NH. The 11/70 is arguably the largest PDP built by Digital Equipment Corporation. This drive on the right is one of two RM03 Massbus disk drives. The right cabinet has the CPU in the bottom and spare parts in the top. The center cabinet has a TU16 tape drive in the top and the tape formatter in the bottom. The left cabinet has a RX02 floppy drive in the top, an RL02 disk in the middle, and two MJ11 core memory chassis in the bottom. It now has 768KB of core memory and has room to expand to 1MB of core memory. The system appears to be complete but will need a little TLC before it will run.

The system has four chassis that contain boards. The chassis on the right contains the processor, Massbus controllers, and a small section of Unibus. It does not have the optional floating point processor. The chassis in the middle contains Unibus I/O boards. The two chassis on the left contain the 12 sections of 32K x 19 bits of core memory.

Unibus I/O Chassis
Slot AB CD EF
1
2
3
4
5
6
7
8
9
10
11
Unibus Cable
M7911 TMB11 tape control 1
12
M7912 TMB11 TMB11 tape control 2
13 M7812 Bus selectors, CSRs, shift registers M796 Unibus master control , M105 Device selector
14
M9202 UNIBUS Jumper Cable
M795 Word count and bus address module
15
16 M9202 UNIBUS Jumper Cable M7800 Async transmitter & receiver, 110-2400 baud
17 M7800 Async transmitter & receiver, 110-2400 baud
18 M7856 RS-232 SLU & realtime clock option
19 M9202 UNIBUS Jumper Cable M7800 Async transmitter & receiver, 110-2400 baud
20
21 M9202 UNIBUS Jumper Cable M7248 Unibus repeater BBSY, M7212 Address line bus repeater control, M7212 Address line bus repeater control, M7212 Address line bus repeater control
22 M784 Bus receiver, M783 Bus transmitters
23 M7213 Bus repeater control, M785 Bus transceiver, M785 Bus transceiver
24 M9202 UNIBUS Jumper Cable M785 Bus transceiver, M785 Bus transceiver
25
26 M9202 UNIBUS Jumper Cable
27 M7821 Interrupt control M796 Unibus master control
28 M7278 DH11 Registers and byte count
29 M7277 DH11 Transmit scanner and NPR
30 M7289 Receiver scanner
31 M7821 Interrupt control, 7-bits M7280 8 UARTS on quad-height board
32 G7360 Priority selector M971 Dual-height blank module M728 11/20 Timing and states module
33 M7288 Line parameters control
34 M9202 UNIBUS Jumper Cable M7279 DH11 FIFO buffer M4540 Crystal clock with simultaneous outputs
35
36 M9202 UNIBUS Jumper Cable
37 M7821 Interrupt control M796 Unibus master control
38 M7278 DH11 Registers and byte count
39 M7277 DH11 Transmit scanner and NPR
40 M7289 Receiver scanner
41 M7821 Interrupt control, 7-bits M7280 8 UARTS on quad-height board
42 G7360 Priority selector M971 Dual-height blank module M728 11/20 Timing and states module
43 M7288 Line parameters control
44 M7279 DH11 FIFO buffer M4540 Crystal clock with simultaneous outputs

There are two Core Memory Chassis in this system.

Core Memory Chassis
Slot AB CD EF
1 G116 N inhibit
2 H224B 32-Kword 18-bit 14-mil core stack
3 G236 32K XY DRIVER (MJ11)
4 G116 N inhibit
5 H224B 32-Kword 18-bit 14-mil core stack
6 G236 32K XY DRIVER (MJ11)
7 G116 N inhibit
8 H224B 32-Kword 18-bit 14-mil core stack
9 G236 32K XY DRIVER (MJ11)
10
11
12
13
M8147 MJ11-A/B 11/70 memory control and timing module
14
M8149 MJ11 11/70 memory transceiver card
15
16
17
18 G116 N inhibit
19 H224B 32-Kword 18-bit 14-mil core stack
20 G236 32K XY DRIVER (MJ11)
21 G116 N inhibit
22 H224B 32-Kword 18-bit 14-mil core stack
23 G236 32K XY DRIVER (MJ11)
24 G116 N inhibit
25 H224B 32-Kword 18-bit 14-mil core stack
26 G236 32K XY DRIVER (MJ11)
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