PDP-11/04
Introduction
The PDP-11/04 was introduced in 1975 as a replacement for the PDP-11/05/10. It was DEC's first UNIBUS single board CPU (KD11-D) on a hex width card (M7263). Other firsts were that it used semiconductor memory versus the core memory used on the PDP-11/05/10 as well as the changeover from a bank of front panel switches as in earlier PDP-11 models to a more streamlined console. Two console options were available; either the KY11-LB programmer's console, as also used on the PDP-11/34, or the standard KY11-LA operator's console with just a rudimentary set of BOOT/INIT and HALT/CONT switches on the front panel. The KY11-LA standard console included the M9301 ROM module which provided a console interface through the user's terminal, in effect, a software based console. There were not many processor expansion options for this low cost model.
It shipped in two chassis configurations: the BA11-L half-height box, which had the entire computer - card guide frame, backplane, power supply, and front panel and a full-height BA11-K box as used throughout the PDP-11/35 line.
Sample Hardware Configuration
- M7263 - KD11-D Processor Card.
- M7847-DJ - MS11-JP 16KW, 18 bit MOS memory hex width card
- M7859 - KY-11LB Programmer's console card.
- M7856 - DL11-W Serial Line controller, Real Time Clock for console terminal.
- M9312 - Unibus bootstrap/terminator.
- M8256 - RX01/02 floppy disk controller.
The CPU board was implemented on a single hex width card containing 138 ICs. The 74181 ALU is used as is on every other DEC PDP-11 processor (most other
minicomputer manufacturers used the AMD2901 ALU).
Some simplifications of the data path and the use of programmable memories has made it possible to decrease the number of ICs.
The CPU is comprised of 256x8 bipolar PROM memories which give a micro code word width of 40 bits; 8 bits are used as address.
Four Intel 3101 16x4 bit static memories were used for the registers.
Source: datormuseum.se
This memory board (M7847) provided 16KBytes of storage. The memory was implemented using 32 MOSTEK MK4096 dynamic memory chips,
each capable of storing 4K X 1 bit. Mostek’s 4-kilobit DRAM chip brought about a key innovation,
a circuitry trick called address multiplexing, concocted by Mostek co-founder Bob Proebsting. Basically, the chip used the
same pins to access the memory’s rows and columns. It did so by sending row and column addressing signals in turn, rather than
all at once as in earlier designs. As a result, the chip didn’t require more pins as memory density increased and could
be made for less money. As such higher memory densities could be placed on a single board due to the smaller footprint of the 16-pin
DIP DRAM package versus the 22 pins used by other memory manufacturers such as Texas Instruments, Intel and Motorola.
Source: datormuseum.se
The M9312 board which is used for bootstrapping the machine and to terminate the UNIBIS.
In a system there needs to be two terminators since there are no termination on the CPU board itself.
Therefore this is the terminator closest to the CPU. An M9302 terminator board has to be installed at the other end of the UNIBUS.
The bootstrap board contains four sockets where one can install bipolar PROMs to support booting from a particular device.
There is also a PROM which contains a console emulator software which uses the serial port to communicate with the operator.
Source: datormuseum.se
Source: computinghistory.org.uk/det/30094/Digital-PDP-11-04-BD/
PDP-11/04 Guides
| Document Name | Order Part No. | Publication Date | Domain |
|---|---|---|---|
| PDP-11/04 System Users Manual | EK-11004-OP-001 | 1976 | HW |
- Adapted from: Wikipedia PDP-11
- Adapted from: datormuseum.se: PDP11/04 Restoration