As already told before in this article series the DECSYSTEM-20 (PDP-10 / KL10) was delivered in 3 cabinets as seen in the following picture. The front end processor (PDP-11/40) was located in the number 1 cabinet, the left most, with the expansion drawer to hold application specific variable system parts. The whole system could have more than 3 cabinets if more space was required.
Cabinet # 1 the left most cabinet
The cabinet # 1 consisted of the following parts:
- RH11 - Massbus Controller (Unibus) for TU45 tape, or RP/RM disk
- MF11-U - Core Memory System
- KD11-A - Processor (PDP-11/35 or PDP-11/40)
- KY11-D - Programmers Console
- DL11-C - Asynchronous Line Interface
- RX11 - Floppy Disc Subsystem
- RX01 - Dual Floppy Disk
- DC20 - DH11's in a KL10 front end (available in 8 or 16 ports)
- DH11 - Asynchronous 16 Line Multiplexer
- LP20 - Line Printer Controller (890 lpm)
- BM873 - Restart Loader ROM
- DL11-E KLINIK - Serial Line Unit / Remote Diagnosis System
- DL11-E - Serial Line Unit (SLU) Real-Time Clock
The following pictures shows cabinet # 1 in more detail and what was in it.
Parts in cabinet 1
Highest there was on the left a RX01 or RX02 dual floppy disc drive. Those used large floppy discs. And on the right the programming console (KY11-C) which was directly connected only to the front end processor but could also serve the main processor (KL10).
Cabinet #1 (front end processor cabinet) in more detail, front view
In the middle of the cabinet there was on the left the expansion drawer and on the right the 11/40 drawer rack. Lowest in the cabinet # 1 there was different power supply parts (the drawers had their own power supplies inside them). Lowest at the rear there was a bulkhead for the slow speed serial terminal and device connectors and also the main power connector to the computer. The configuration shown allows at least 32 terminals to be connected to the system using standard serial connectors. The connector pin numbering could be separately set for each line using the DIL switche next to the connector.
Cabinet #1 (front end processor cabinet) in more detail, rear view
When you pull out the front end processor drawer in the cabinet # 1 you have access to the UNIBUS chassis modules or PCB's.
Drawer local power supplies and fans were located to the right and up in the drawer
On the left there were the actual modules or printed circuit boards (PCB). First in the row there was the KD11-A in 5 or so modules. One card is set on a riser to be debugged with an oscilloscope
Photo of an earlier DECSYSTEM-10 front end (the console is attached to the drawer)
The 11/40 rack contained KD11-A, MF11-UP, RH11-AB and 2 DD11-B functional parts which can further be divide to several individual cards.
PDP11-40 drawer (See above)
Slot AB CD EF
1
2
3 M7232 11/40 micro word module M787
4 M7231 11/40 data paths module
5 M7233 11/40 IR decode module
6 M7235 11/40 processor status module
7 M7234 11/40 timing module
8
9 M7800 ASYNCHRONOUS LINE INTERFACE & RCVR,KL1 DLV11-M
M981 for PDP11/34
1 M8293 UNIBUS 16K TIMING & CONTROL
2 M7259 MODULE PARITY Control
3 G114 16K sense memory, XY Drive
4 H217C Stack modul, Core Memory 32K * 18
5 G235 16K XY Drive, Current source, Decode
6 G235 16K XY Drive, Current source, Decode
7 H217C Stack modul, Core Memory 32K * 18
8 G114 16K sense memory, XY Drive
9 M8293 UNIBUS 16K TIMING & CONTROL
M9202 1"APART W/2'C , UNIBUS CONNECTOR
RH11-AB Massbus Controller (Unibus) for TU45 tape, or RP/RM disk
1 M7297 MASSBUS parity control M7296 MASSBUS control and status registers
2 M7295 MASSBUS CONTROL RH11
3 M7294 RH11 MASSBUS data buffer and control
4 M5904 MASS BUS CONTROL TRANSCEIVER, PDP-11
5 M5904 MASS BUS CONTROL TRANSCEIVER, PDP-11
6 M5904 MASS BUS CONTROL TRANSCEIVER, PDP-11
7 G727 Grant continuity card with DMA link (NPR), single (CR11)
8 M9300 UNIBUS B TERMINATOR G727 Grant continuity card with DMA..
9 G727 Grant continuity card with DMA link (NPR), single (CR11)
DD11-B UNIBUS Backplane, Peripheral Mounting Panel, 4 SPC's and 2 DF11's
1 M7800 ASYNCHRONOUS LINE INTERFACE & RCVR,KL1 DLV11-M
2 BM873YJ Restart Loader
3 M7846 RX01 UNIBUS INTERFACE
4 G727 Grant continuity card with DMA link (NPR), single (CR11)
M9202 1"APART W/2'C , UNIBUS CONNECTOR
DD11-B UNIBUS Backplane, Peripheral Mounting Panel, 4 SPC's and 2 DF11's
1 G727 Grant continuity card with DMA link (NPR), single (CR11)
2 G727 Grant continuity card with DMA link (NPR), single (CR11)
3 G727 Grant continuity card with DMA link (NPR), single (CR11)
4 G727 Grant continuity card with DMA link (NPR), single (CR11)
The second drawer in the cabinet 1 contained the expansion modules.
Cabinet # 1, Expansion drawer rack. Inside it CD20, LP20 x 2, DC20F x 2 and DB11-M
Expansion drawer (see above) (without listing individual modules)
DB11-M UNIBUS Repeater
DC20-F DH11's in KL front end (available in 8 or 16 ports)
DC20-F DH11's in KL front end (available in 8 or 16 ports)
LP20 Unibus Line printer interface (RSX20F or DN20/21)
LP20 Unibus Line printer interface (RSX20F or DN20/21)
CD20 Card Reader Controller
Modules or PCB's in racks
A full size front end UNIBUS rack could hold a hex size UNIBUS printed circuit board or module. Several smaller UNIBUS cards could be held parallel in the same slot.
Standard UNIBUS card sizes (PDP11 was fully an UNIBUS computer)
For example the following quad height UNIBUS card M7846 (the floppy disk controller interface) resided in the 3rd slot of the DD11 block in the 11/40 UNIBUS drawer filling only 2/3 of the full slot.
Quad height DEC UNIBUS RX11 Floppy Disk Controller M7846 card
The other cards were similar.
Each PDP-11/40 can access the KL10 memory via indirect address pointers and transfer data in much the same manner as the peripheral processing units of a CDC 6600. Notice also that the KL10's console is tied to the PDP-11/40. This PDP-11 can load the KL10 microprogram memory, run microdiagnostics, and provide a potential remotely operated console. Each of the PDP-11s can achieve a word rate of 70 Kchar/second.
[The next part in this series will handle the cabinet # 2 in more detail.]
REFERENCES
/1/ MP01708_KL10-R_System_Drawings_Sep83.pdf
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