RK11-C disk controller
The RK11-C is the earliest version of the RK11 disk controller. (Nothing is known of the -A and -B, if they ever existed as products.)
Like many of the earlier large peripheral controllers for the PDP-11, it was a large custom wire-wrapped backplane which bolted into the front of a 19 inch rack, such as an H960; into it plugged about 40 small M-Series FLIP CHIPs.
The backplane is wired for connection to a standard DEC indicator panel, but no inlay for such has even been sighted, although the RK11-C Engineering Drawings allow one to work out exactly what such an inlay would have looked like. It does however appear than an earlier version did have such an indicator panel.
Contents
Double Buffered RK11-C
There is also a rare variant of the RK11-C, the 'Double Buffer' RK11-C. It adds two 16-bit buffer registers (ABUF and BBUF), which are chained in an alternate data path between the UNIBUS and RKDB buffer register.
The motivation is not explicitly known (no documentation other than the engineering drawings is now extant), but it likely prevented under-run errors when there was considerable competing UNIBUS DMA traffic.
Engineering drawings
The engineering drawings for the Double Buffer RK11-C are very similar to those of the standard RK11-C. The differences are listed below.
Note: The engineering drawings available online for the original RK11-C are missing pages 18 and 19:
- 18 - Disk Cable and Termination
- 19 - Bus "D" Drvrs and Rcvrs
The Double Buffer set inludes those pages, numbered 21 and 18 there, respectively. (The re-numbering of that first drawing from 18 to 21 caused the prints numbered from 19 to 21 in the original RK11-C set to be numbered one lower in the Double Buffer set; e.g. RKDB Data Paths was 21 in the original RK11-C set, and is 20 in the Double Buffer set.)
New prints:
- 24 - DSB/Bus -> ABuf Controls
- 25 - ABuf/BBug Reg
- 26 - Interbuffer Transfer Control
- 27 - Buffer Control
Major changes:
- 10 - RKDB and Control
- 11B - Reg Sel, NPR & Int Control
Minor changes:
- 13 - Adder Control (Adder Control #2 flop set input logic)
- 15 - RKBA - RKWC - RKMR (logic lower left corner)
- 16 - Errors (logic center driving DLT flop)
- 17 - Cable Drivers (hand-written gate lower left)
- 20 - RKDB Data Paths (replace 'BUS D' with 'BBUF' on all data bits)
RK11-C module count/location tables
The following tables give a listing of the Flip Chips used in the RK11-C, and their location in the backplane.
Module counts
(Drawn from module utilization drawing, confirmed in module count chart):
Single height boards:
| Type | Count | Function |
|---|---|---|
| G736 | Jumper | |
| G740 | Disk selection | |
| M002 | 15 Loads | |
| M105 | Address selector | |
| M111 | 2 | Inverter |
| M112 | 5 | NOR gate |
| M113 | 7 | 10 x 2-Input NAND gates |
| M115 | 3 | 8 x 3-Input NAND gates |
| M116 | 3 | 6 x 4-Input NOR gates |
| M117 | 3 | 6 x 4-Input NAND gates |
| M119 | 2 | 3 x 8-Input NAND gates |
| M121 | 3 | AND/NOR gates |
| M141 | 2 | NAND/NOR gates |
| M149 | 10 | 9 x 2-NAND wired OR matrix |
| M161 | Binary to octal/decimal decoder | |
| M163 | Dual binary to decimal decoder | |
| M203 | 4 | 8 x SR flip-flops |
| M205 | 3 | 5 x 'D' flip-flops |
| M207 | J-K Flip-flops (3-3 configuration) | |
| M208 | 2 | 8-bit buffer shift register |
| M214 | 3 | 6-bit register |
| M216 | 5 | 6 x flip-flops |
| M236 | 12-bit binary up/down counter | |
| M238 | Synchronous 4-bit up/down counter | |
| M239 | 2 | 3 x 4-bit up/down counter/register |
| M304 | 3 | One shot delay |
| M307 | 3 | Integrating one shot |
| M405 | Crystal clock | |
| M611 | High speed power inverter | |
| M617 | 6 x 4-input NAND buffers | |
| M623 | 3 | Bus driver |
| M782 | Interrupt control | |
| M784 | 3 | UNIBUS receivers |
| M796 | UNIBUS master control | |
| M797 | Register select | |
| M798 | UNIBUS drivers | |
Double height boards:
- M795 - Word Count and Current Memory Address
Module Utilization Chart
The Flip Chip module utilization chart for the RK11-C backplane is as follows (* = Connector):
| Slot | A | B | C | D |
|---|---|---|---|---|
| 1 | UNIBUS in | |||
| 2 | UNIBUS out | |||
| 3 | ||||
| 4 | ||||
| 5 | M105 | M784 | ||
| 6 | M782 | M79 | ||
| 7 | M795 | |||
| 8 | M784 | M784 | ||
| 9 | M623 | M307 | ||
| 10 | Disk bus 2* | M623 | M307 | |
| 11 | M623 | M307 | ||
| 12 | Disk bus 1* | M207 | M163 | |
| 13 | M798 | G736 | G740 | M405 |
| 14 | M149 | M149 | M116 | M161 |
| 15 | M149 | M149 | M304 | M119 |
| 16 | M149 | M149 | M113 | M113 |
| 17 | M239 | M238 | M216 | M141 |
| 18 | M239 | M214 | M115 | M115 |
| 19 | M214 | M214 | M121 | M112 |
| 20 | M208 | M208 | M111 | M111 |
| 21 | M203 | M203 | M112 | M112 |
| 22 | M149 | M149 | M205 | M117 |
| 23 | M149 | M149 | M203 | M203 |
| 24 | M121 | M002 | M116 | M115 |
| 25 | M216 | M797 | M611 | M617 |
| 26 | M141 | M119 | M113 | M304 |
| 27 | M304 | M112 | M112 | M113 |
| 28 | M236 | M121 | M216 | M216 |
| 29 | M205 | M117 | M117 | |
| 30 | W130* | M113 | M113 | |
| 31 | 6775* | M113 | M205 | |
| 32 | 6775* | M116 | M216 | |
W130 = Maintenance board
6775 = Cable to indicator panel
Double Buffered RK11-C module count/location tables
The following tables give a listing of the Flip Chips used in the Double Buffered variant of the RK11-C, and their location in the backplane.
Module counts
(Drawn from module count chart):
| Type | Count | Function |
|---|---|---|
| G736 | Jumper | |
| G740 | Disk selection | |
| M002 | 3 | 15 Loads |
| M105 | Address selector | |
| M111 | 5 | Inverter |
| M112 | 7 | NOR gate |
| M113 | 10 | 10 x 2-Input NAND gates |
| M115 | 4 | 8 x 3-Input NAND gates |
| M116 | 3 | 6 x 4-Input NOR gates |
| M117 | 4 | 6 x 4-Input NAND gates |
| M119 | 2 | 3 x 8-Input NAND gates |
| M121 | 3 | AND/NOR gates |
| M141 | 2 | NAND/NOR gates |
| M149 | 12 | 9 x 2-NAND wired OR matrix |
| M161 | Binary to octal/decimal decoder | |
| M163 | Dual binary to decimal decoder | |
| M203 | 4 | 8 x SR flip-flops |
| M205 | 4 | 5 x 'D' flip-flops |
| M207 | J-K Flip-flops (3-3 configuration) | |
| M208 | 6 | 8-bit buffer shift register |
| M214 | 3 | 6-bit register |
| M216 | 5 | 6 x flip-flops |
| M236 | 12-bit binary up/down counter | |
| M238 | Synchronous 4-bit up/down counter | |
| M239 | 2 | 3 x 4-bit up/down counter/register |
| M304 | 5 | One shot delay |
| M307 | 3 | Integrating one shot |
| M405 | Crystal clock | |
| M606 | 2 | Pulse generator |
| M611 | High speed power inverter | |
| M617 | 6 x 4-input NAND buffers | |
| M623 | 3 | Bus driver |
| M782 | Interrupt control | |
| M784 | 3 | UNIBUS receivers |
| M796 | UNIBUS master control | |
| M797 | Register select | |
| M798 | UNIBUS drivers | |
Double height boards:
- M795 - Word Count and Current Memory Address
Module Utilization Chart
The Flip Chip module utilization chart for the RK11-C backplane is as follows (* = Connector):
| Slot | A | B | C | D |
|---|---|---|---|---|
| 1 | UNIBUS in | M606 | M113 | |
| 2 | UNIBUS out | M115 | M002 | |
| 3 | M149 | M149 | M208 | M208 |
| 4 | M111 | M002 | M205 | M113 |
| 5 | M105 | M784 | M208 | M208 |
| 6 | M782 | M796 | M304 | M304 |
| 7 | M795 | M606 | M112 | |
| 8 | M784 | M784 | M112 | M111 |
| 9 | M117 | M111 | M623 | M307 |
| 10 | Disk bus 2* | M623 | M307 | |
| 11 | M113 | M623 | M307 | |
| 12 | Disk bus 1* | M207 | M163 | |
| 13 | M798 | G736 | G740 | M405 |
| 14 | M149 | M149 | M116 | M161 |
| 15 | M149 | M149 | M304 | M119 |
| 16 | M149 | M149 | M113 | M113 |
| 17 | M239 | M238 | M216 | M141 |
| 18 | M239 | M214 | M115 | M115 |
| 19 | M214 | M214 | M121 | M112 |
| 20 | M208 | M208 | M111 | M111 |
| 21 | M203 | M203 | M112 | M112 |
| 22 | M149 | M149 | M205 | M117 |
| 23 | M149 | M149 | M203 | M203 |
| 24 | M121 | M002 | M116 | M115 |
| 25 | M216 | M797 | M611 | M617 |
| 26 | M141 | M119 | M113 | M304 |
| 27 | M304 | M112 | M112 | M113 |
| 28 | M236 | M121 | M216 | M216 |
| 29 | M205 | M117 | M117 | |
| 30 | W130* | M113 | M113 | |
| 31 | 6775* | M113 | M205 | |
| 32 | 6775* | M116 | M216 | |
W130 = Maintenance board (optional)
6775 = Cable to indicator panel
