• General system information
• Differences between 11/34 and 11/34A processor
• PDP-11/34A programmer's console description
• This PDP-11/34A system configuration
• PDP-11/34A processor (and options) power requirements

## picture of complete PDP-11/34A system (to be added) ##

System history

This PDP-11/34A has been used at the Technical University "Twente", in the eastern part of the Netherlands.
I got it from a group of students. They 'sold' it to me for a crate (this is 24 bottles) of beer. With it came a TU56 dual DECtape drive! Unfortunately, the TC11 controller was in an other cabinet, that the students did not think of being important ...
I want to connect the TU56 to the PDP-11/35 system from a more historical point of view.

System description

My PDP-11/34A consists of the basic KD11-EA 11/34A Central Processing Unit, and is equiped with all PDP-11/34A available processor options. The processor boards and the options are all described on the page CPU information.
This is a subfolder of the PDP-11/34A folder. The PDP-11/34A processor options are :

KK11-A Cache Memory FP11-A Floating Point Processor KY11-LB Programmer's Console The system is completed with the following peripherals : disk storage units RX02 dual 8" floppy disk RL01 and RL02 removable pack drives RK07 removable pack drives magnetic tape storage units TS03 industrial format 0.5" tape (7" open reel) communication devices and interfaces line printer LA210 monitor console VT102 DELUA Ethernet network interface

When you click on the link you can read more about the specific peripheral device. All peripherals that I have are also described in the 'subfolder' peripherals, on which you can click in the navigation section at the left.
To return to this location, click on the text 'PDP-11/34A' after the first subfolder.
I hope to add an original DIGITAL paper tape reader/punch unit (PC11) to this system in the future.
So, if you have one, and you want to get rid of it (...), please contact me.

module   PDP-11/34     PDP-11/34A   identification KD11-E KD11-EA data path M7265 M8265 control M7266 M8266   SACK time-out   M8264 ---	The KD11-E processor consists of three boards, whereas the KD11-EA has only two boards. Both processor boards of the 11/34 and the 11/34A are multi-layer and are hex-height modules. Extended Instruction Set (EIS) is a standard feature for the KD11-E(A). The KD11-E(A) also contains memory management logic to extend the memory space from 28k to 124k word.
The 11/34A was developed to add the floating point option FP11-A and includes the SACK time-out circuitry and the required connections for the floating point option. Also, the power supply of the PDP-11/34A has more output Amps to support the FP11-A.

Back to top

The PDP-11/34 has two different consoles, the basic console KY11-LA, and the more elaborate console KY11-LB.
The KY11-LA console has just two switches, a rotary 3-position switch and three indicators.
The optional KY11-LB has a 20-pushbutton keypad, six indicator LED's, a six digit 7-segment display for address and data and a DC power switch. The KY11-LB interfaces to the UNIBUS via the quad-height module M7859. This board must be installed in the processor backplane.

• KY11-LB indicators
  The indicators BATT, DC ON and RUN function in the same manner as described in the next paragraph, KY11-LA indicators.

  KY11-LB programmer's console indicators
  six 7-segment displays	The 7-segment display represents the current address or the contents of the current address. Each segment of the display shows an octal digit (0-7). Six digit numbers are generated as octal digits and are entered from the right and left-shifted.
  SR DISP	Switch Register Display - Indicates, when on, that the contents of the Switch Register (address 777570) is displayed.
  MAINT	Maintenance - Indicates, when on, that the console is operating in maintenance mode.
  BUS ERR	Bus Error - Indicates, when on, that an examine or a deposit resulted in a SSYN timeout, or that HALT GRANT was not received after a HALT REQUEST was issued. Note: this indicator reflects a bus error by the console only. The indicator does not reflect bus errors due to other devices such as the processor

• KY11-LB pushbutton keypad
  The rotary 3-position switch functions in the same manner as described in the next paragraph, KY11-LA switches.

  KY11-LB programmer's console keypad
  0,1,2,3,4,5,6,7	Allows the operator to enter octal data into the display.
  LSR	Load Switch Register - A copy of the contents of the display is stored in UNIBUS address 777570.
  LAD	Load Address - The contents of the display becomes the current address. The display is cleared when LAD is pressed.
  DIS AD	Display Address - The current address is displayed. The next examine or deposit will occur at the address displayed.
  CLR	Clear - The display is cleared in preparation for entry of new data via the number keys.
  EXAM	Examine - A copy of the data contained in the location specified by the current address is shown in the display. This key is operative only when the processor is halted.
  DEP	Deposit - A copy of the data being displayed is transfered to the location specified by the current address. This key is operative only when the processor is halted.
  CNTRL	Control - The Control key is used in conjunction with other keys to provide certain functions. The requirement of having both CNTRL and the second key pressed at the same time prevents accidental use of these functions.
  CNTRL key controlled functions
  INIT	Initialize - Causes BUS INIT L to be generated for 150 mSec. This key is operative only when the processor is halted.
  HALT/SS	Halt / Single Step - Halts the processor if the processor is running. To single step the processor, halt the processor, then press the HALT/SS key without pressing the CNTRL key. After a halt, the display will contain the contents of R&, the program counter.
  CONT	Continue - Allows the processor to continue from a halted state using its current program counter. The contents of the Switch Register is displayed.
  START	Start - This key is operative only if the processor is halted. The function causes the program counter (R7) to be loaded with the current address. BUS INIT L is then generated and the processor is allowed to run. Switch Register contents is then displayed.
  BOOT	Boot - Causes the M9312 (or other bootstrap/terminator) to be activated if present in the system. Console will boot only if the processor is halted.
  button 7	When keypad button #7 and CNTRL are both pressed, the current address plus the value presently being displayed plus 2 are added together. The result is then displayed. This function allows the console to calculate the correct offset address when mode 6 or 7, register 7 instructions are encountered. The required index must be in the display so that when the keys are pressed, the index will be added to the PC+2. The offset address is the displayed.
  button 6	When keypad button #6 and CNTRL are both pressed, the contents of the Switch Register are added to the value presently being displayed. The result is then displayed. This function allows the console to calculate the correct offset address when mode 6 or 7 instructions that do not use register 7 are encountered. To implement this function, it is easiest to put the index in the Switch Register, the examine the general register that contains the base address, thereby placing the base address in the display. Then, when the #6 key and CNTRL are both pressed, the index and base address will be added and the correct offset address will be displayed.
  button 1	Maintenance Mode - This key combination puts the console in maintenance mode. When the console is in maintenance mode, normal console mode keypad functions are not available. The CLR key causes the console to exit from maintenance mode and enter console mode via a processor halt.

• KY11-LA indicators
  

  KY11-LA basic console lights
  BATT	off	battery voltage is below the minimum level required to maintain the contents of the MOS memory, or the battery is not present in the system
  	slow flash (1 flash per 2 sec)	battery is charging and the voltage is above the required level to maintain the contents of th MOS memory if power is removed
  	fast flash (10 flashes per sec)	primary power is lost and the battery is discharging while maintaining MOS memory contents
  	on	battery is present and fully charged
  DC ON	on	DC power is applied to the logic. It does not imply that the power is within the required levels
  	off	DCpower is off
  RUN	on	indicates either: 1. - processor is executing, or 2. - processor is attempting to run, but is disabled due to a system failure
  	off	processor is halted

• KY11-LA switches
  

  KY11-LA basic console switches/buttons
  3 position rotary switch	DC OFF	DC power removed from the system, contents of MOS memory are lost and fans are off. NOTE: this does not remove AC power!
  	DC ON	power is applied to the computer system
  	STNDBY	DC power to the computer is off, but DC power is applied to MOS memory.
  HALT/CONT   (2 position toggle)	HALT	program is stopped
  	CONT	program is allowed to continue
  BOOT/INIT (spring-action, momentary)	INIT	if HALT/CONT is in the HALT position, only the processor is initialized and peripheral device registers are not cleared if HALT/CONT is in the CONT position, the processor is initialized, peripheral device registers are cleared and the bootstrap program is executed

A backplane that supports a complete function is called a system unit. The DD11-CK and the DD11-DK are examples of general purpose system units. They can have several boards with different functions in its backplane.
Every system unit has an UNIBUS-in and a UNIBUS-out slot. The 'out'-section connects to the 'in'-section of the next system unit with a "module bridge" connector.

The DD11-PK basic PDP-11/34 processor system unit has 9 slots of which the first two are dedicated to the processor. As this system unit is the first in a PDP-11/34A, there is no UNIBUS-in. That is actually on the processor board in slot #1 (M8266, datapaths module). The last (9th) slot of this system unit has the UNIBUS-out and a so-called SPC slot. SPC stands for 'Small Peripheral Connection'. This SPC-slot commonly holds the interface card to connect the system console.

The DD11-DK is a 9 slot general purpose back plane. In my configuration this system unit holds the following modules.

• RL11 (M7762) interface for the RL drives
• RX211 (M8256) interface for the RX02 floppy drives
• MS11-LD (M7891-DF) 128-Kword 18-bit parity MOS memory
• DL11-W (M7856) serial line unit
• DELUA (M7521-AA) Ethernet interface

The last backplane is the TMB11 option. This is a 4-slot dedicated system unit for the support of the TU10 or TS03 tape drive. The last slot, position A-B holds the UNIBUS terminator (M9302) for a single BA11 box PDP-11/34(A) system, but in my PDP-11/34, a BC11-A cable connects to a second BA11 box. This BA11 expansion box holds the RK611 controller to which two RK07 removable pack disk drives are connected.

All slots that are not used (in the general purpose backplanes) must have a grant-continuity card (G727A) in position D to continue the UNIBUS. An other important connection which can cause a lot of problems is the connection between pins CA1 and CB1 in position C. These two pins carry the NPG (Non Processor Grant) signal, and acts as a "handshake" between two devices for a data transfer (nowadays called DMA, Direct Memory Access). Normally the connection between these two pins is shorted by a wire on the backplane. When you install a module that does DMA (for example the RL11 controller) you must cut the wire between CA1 and CB1 in position C. If that module is removed, you must restore the connection between these two pins on the backplane, or install an other option that either uses DMA or connects these pins (in-out of the daisy-chain), or install a grant module G7273 in the free slot, positions C-D. The G7273 has the four connect-throughs of the G727A and connects CA1 to CB1 to continue the NPG daisy-chain on the backplane.
If one slot is left open, the system will hang. This is a common error cause when a board is removed that used DMA. You can recognize the situation of a broken NPG chain because the "RUN" light will always stay on, and the system will not 'listen' when you try to halt the system (when you press "CNTRL" and "HLT/SS" at the same time).

All the system units are interconnected with a M9202 module bridge.

The DD11-PK processor backplane can hold the following (processor-specific) modules.

• The two basic PDP-11/34A processor boards, M8265 and M8266
• The KY11-LB programmer's console interface board, M7859
• The FP11-A floating point processor option board, M8267
• The KK11-A cache memory option board, M8268

• a console interface board and real-time clock, DL11-W, M7856 (quad, SPC)
• interface for the RX02 floppy drive, RX211, M8256 (quad, SPC)
• interface for the RL01/RL02 disk drive, RL11, M7762 (hex)
• one or more MOS memory boards, MS11-L, M7891 (hex)

processor board / option	power requirements
basic 11/34A processor M8265 / M8266	11.5 Amps @ 5 Volt
KY11-LB programmer's console M7859	3.0 Amps @ 5 Volt
FP11-A floating point processor M8267	7.0 Amps @ 5 Volt
KK11-A cache memory option M8268	4.0 Amps @ 5 Volt
MR11-EA bootstrap/terminator M9312	2.0 Amps @ 5 Volt
DL11-W SLU and RTC M7856 (console)	2.0 Amps @ 5 Volt

The KK11-A cache memory technical manual (EK-KK11A-TM-001) contains detailed information where to install the KK11-A option with or without the FP11-A installed in the system, and points out the power requirements.