This page is about the MINC-11 in the System Source collection in Hunt Valley, Maryland.
Current Status
I visited System Soure in June 2022 and spent some time working on this MINC-11, attempting to get it running.
It comes up with a PDP-11/03 ODT prompt, if the Normal/Halt switch on the BDV-11 is toggled from Normal-to-Halt and then back to the Normal position. It can also successfully download (but not run) a TU58 emulator bootstrap from PDP11GUI over the Console cable.
However, it is currently unable to:
- Download an RX02 image to an 8″ drive attached to the DQ419 using PDP11GUI; or
- Run the TU58 bootstrap once it has been downloaded
When the TU58 bootstrap is run, the SLU Channel 0 TXD line gets held permanently in the SPACE (+VOLTAGE) condition (ie RS232 Break signal) because the bootstrap progams halts early in its execution. It halts as soon as the instruction “call xmtcmh8” is executed (it halts at 002142, which is unrelated to the address space used by the bootstrap program).
This problem is suspected to be caused by a fault on the 11/03 processor board (M7270), althrough it could possibly be caused by an unserviced Trap condition triggered by some other event. Note we did temporarily install the W3 link on the M7270 board to prevent LTC interrupts. This however did not fix the problem, and the W3 link was eventually removed again.
Console and TU58 emulator cables (both DB9F-to-DB9F), to connect to a PC via USB-to-RS232 dongles, have been fabriacted and are working fine. They have been left inside the MINC. The back panel has 4 x DB9M plugs on it. The top position (marked Console) is for the console. The next position down (marked “SLU2″) is temporarily being used for SLU0 (the TU58 Emulator) as the wiring to the other 2 DB9Ms is faulty.
The serial ports on the MINC are configured as follows:
CH0: 38400, N, 8, 1 [TU58 emulator]
CH1: 300, N, 8, 2
CH2: 9600, N, 8, 2
CH3: 9600, N, 8, 1 [Console]
The BDV11 is most likely currently configured to boot the MINC software off an RX02-format 8” diskette via the DQ419 controller.
Next Steps
Next steps to get this machines running are as follows:
- Obtain a known good M7270 and install it in the MINC
- Hookup a PC running both PDP11GUI (to download a TU58 emulator bootstrap to the MINC, and to provide a Console terminal) and TU58EM (hosting a bootable RT11 TU58 image) to the MINC
- Download the TU58 bootstrap to the MINC using PDP11GUI
- Execute the TU58 bootstrap on the MINC (using the ODT command “10000G”) and check that RT11 loads on the MINC
- Hookup 1 or 2 standard (not DEC RX01 or DEC RX02) drives to the DQ419 controller
- Check out the DQ419 subsystem (ensure RX02 disks can be written and read under RT11)
- Use PDP11GUI to write the Bitsavers MINC 11/03 disk images to the drive connected to the DQ419
- Boot the MINC from the floppy drive and checkout the MINC I/O boards using the MINC software
- Repair the SLU0 and SLU1 connector wiring on the back panel, and arrange the 4 x 10-pin connectors on the DLV11-J appropriately
The 2 serial cables that go between the MINC and the PC are DB9F at both ends. But the ends are NOT interchangeable. The MINC and PC ends are labelled respectively in black ink.
Board List
The MINC-11 has the following boards installed:
| Board | Description |
|---|---|
| M7270 | PDP-11/03 CPU |
| M8044 | 32KW RAM (28KW useable) |
| Dilog DQ419 | RX02 workalike board for “normal” 8″ floppy drives |
| M7954 | IEEE-4888 GPIB Interface |
| M8659 | Grant Continuity Card |
| M8659 | Grant Continuity Card |
| M8043 | DLV11-J SLU Interface |
Then in the instrumentation section:
| Board | Description |
|---|---|
| MNCKW | Clock Module |
| MNCDO | Digital Out Module |
| MNCAD | A/D Module |
Then the terminator:
| Board | Description |
|---|---|
| M8012 | BDV11 Terminator and Boot Module |
Console Cable
A small module hanging off the back of the MINC-11 back panel houses the 4 x DB9M connectors from the SLU.
The top connector is for the Console. It connects to Port 3 (left-hand position) on the M8044 (DLV11-J).
The wiring on the DB9M connectors is non-standard (TXD and RXD are NOT on pins 2 and 3).
Looking into the DB9M from the mating side with 5 pins on the top row, and 4 pins on the bottom row):
- Pin 1 is at the left end of the row of 5 pins
- Pin 5 is at the right end of the row of 5 pins
- Pin 6 is at the left end of the row of 4 pins
- Pin 9 is at the right end of the row of 4 pins
The cable details to connect the MINC to a USB-to-RS232 dongle are as follows:
| MINC End DB9F |
Signal | PC End DB9F |
|---|---|---|
| 3 | Ground | 5 |
| 4 | MINC-11 TX Data | 2 |
| 7 | MINC-11 RX Data | 3 |
| 8,6 | Loop these pins | N/C |
The TU58 Emulator uses the same cable as the Console. It connects via the MINC back panel to the DLV11-J’s right-hand connector (SLU Channel 0).
TU58 Bootstrap
This is the bootstrap I’ve been using for the MINC-11:
M9312 'DD' BOOT code for TU58 D MACRO V05.05 Thursday 15-Apr-99 12:00 Page 1
1
2 .title M9312 'DD' BOOT code for TU58 DECtapeII serial tape controller
3
4 ; This source code is taken from M9312 boot PROM for the TU58 version 23-765B9.
5 ;
6 ; This boot PROM is for the TU58 DECtapeII serial tape controller.
7 ;
8 ; Multiple units and/or CSR addresses are supported via different entry points.
9 ;
10 ; Revision history:
11 ; March 2017: Joerg Hoppe
12 ; Made relocatable, adaption for tu58fs.
13 ;
14 ; 2009?: Don North / AK6DN ?
15 ; The original code in 23-765A9 is REALLY BROKEN when it comes to
16 ; supporting a non-std CSR other than 776500 in R1 on entry
17 ; All the hard references to: ddrbuf, ddxcsr, ddxbuf
18 ; have been changed to: 2(R1), 4(R1), 6(R1)
19 ; The one reference where 'ddrcsr' might have been used is '(R1)' instead
20 ; which is actually correct (but totally inconsistent with other usage).
21 ;
22 ; 1978?: DEC
23 ; Original ROM 23-765B9 for M9312.
24 ;
25
26 176500 ddcsr =176500 ; std TU58 csrbase
27
28 000000 ddrcsr =+0 ; receive control
29 000002 ddrbuf =+2 ; receive data
30 000004 ddxcsr =+4 ; transmit control
31 000006 ddxbuf =+6 ; transmit data
32
33 000000 .asect
34 010000 .=10000 ; arbitrary position
35
36 ; --------------------------------------------------
37
38 010000 start:
39
40 010000 000261 dd0n: sec ; boot std csr, unit zero, no diags
41 010002 012700 000000 dd0d: mov #0,r0 ; boot std csr, unit zero, with diags
42 010006 012701 176500 ddNr: mov #ddcsr,r1 ; boot std csr, unit
43
44 010012 012706 002000 go: mov #2000,sp ; setup a stack
45 010016 005004 clr r4 ; zap old return address
46 010020 005261 000004 inc ddxcsr(r1) ; set break bit
47 010024 005003 clr r3 ; data 000,000
48 010026 004767 000050 call xmtch8 ; transmit 8 zero chars
49 010032 005061 000004 clr ddxcsr(r1) ; clear break bit
50 010036 005761 000002 tst ddrbuf(r1) ; read/flush any stale rx char
51 010042 012703 004004 mov #<010*400>+004,r3 ; data 010,004
52 010046 004767 000034 call xmtch2 ; transmit 004 (init) and 010 (boot)
53 010052 010003 mov r0,r3 ; get unit number
54 010054 004767 000030 call xmtch ; transmit unit number
55
56 010060 005003 clr r3 ; clear rx buffer ptr
57 010062 105711 2$: tstb (r1) ; wait for rcv'd char available
58 010064 100376 bpl 2$ ; br if not yet
59 010066 116123 000002 movb ddrbuf(r1),(r3)+ ; store the char in buffer, bump ptr
60 010072 022703 001000 cmp #1000,r3 ; hit end of buffer (512. bytes)?
61 010076 101371 bhi 2$ ; br if not yet
62 010100 005007 clr pc ; jump to bootstrap at zero
63
64 010102 xmtch8: ; transmit 4x the two chars in r3
65 010102 004717 jsr pc,(pc) ; recursive call for char replication
66 010104 xmtch4:
67 010104 004717 jsr pc,(pc) ; recursive call for char replication
68 010106 xmtch2: ; transmit 2 chars in lower r3, upper r3
69 010106 004717 jsr pc,(pc) ; recursive call for char replication
70 010110 xmtch: ; xmt char in lower r3, then swap r3
71 010110 105761 000004 tstb ddxcsr(r1) ; wait for xmit buffer available
72 010114 100375 bpl xmtch ; br if not yet
73 010116 110361 000006 movb r3,ddxbuf(r1) ; send the char
74 010122 000303 swab r3 ; swap to other char
75 010124 000207 return ; rts pc ; now recurse or return
76
77 000001 .end
Symbol table
DDCSR = 176500 DDRCSR= 000000 DD0D 010002 START 010000 XMTCH4 010104
DDNR 010006 DDXBUF= 000006 DD0N 010000 XMTCH 010110 XMTCH8 010102
DDRBUF= 000002 DDXCSR= 000004 GO 010012 XMTCH2 010106
Pictures
Resources
F.J. Kraan’s MINC-11 page
MINC-11 Documentation on Bitsavers
F.J. Kraan’s MINC-11 Documentation
MINC-11 RX02 disk images on Bitsavers
PDP11GUI
AK6DN’s TU58 Emulator (You will also need to find and install “cygwin1.dll” in the same directory)
MNC11 Field Maintenance Print Set, DEC Order No. MP00652 (for PDP-11/03 MINC)
MDL23 Field Maintenance Print Set, DEC Order No. MP01074 (for PDP-11/23 MINC)
TU58EM Start Command
tu58em -p 7 -s 38400 -S 1 -r rt53sml-copy.t58 -w junk.t58 -T