This page captures my rough working notes regarding QBUS systems.
You probably won’t find anything greatly useful here. It is mainly a place for me to records things that I seem to continually forget the details of!
BA11-NC Chassis
This is a 9 row 18-bit ABCD chassis. So dual-height cards get aligned with the left-hand edge of the backplane (the AB slots), and there is no need to put grant continuity boards (M9047) in the unusued CD slots.
The Processor board goes in the top slot.
Sigma Information Systems BA11 Chassis
I like this chassis because it has PWR, LTC, BOOT and Halt switches on the front panel, as well as providing access to the QBUS boards through the front panel.
This is a 9-row [XX]-bit ABAB chassis. The processor board goes in the top left slot. The grant continuity chain goes in serpentine fashion (Row 1 left, Row 1 right, Row 2 right, Row 2 left, etc).
DLV11-J 4-Port SLU Board (M8043)
The main document is the DLV11-J User’s Guide.
This board has a vast number of jumpers on it.
The baud-rate pins are:
- U: 150 baud
- T: 300 baud
- V: 600 baud
- W: 1200 baud
- Y: 2400 baud
- L: 4800 baud
- N: 9600 baud
- K: 19200 baud
- Z: 38400 baud
Looking at the 10-pin connectors, from left-to-right, my configuration is usually:
- Channel 3 (Console) wired to Pin N (9600 baud)
- Channel 2 (Unallocated) wired to Pin T (300 baud)
- Channel 1 (Serial Printer) wired to Pin W (1200 baud)
- Channel 0 (TU58 Emulator) wired to Pin Z (38400 baud)
Pin 10 supplies +12V to peripherals. The User’s Guide says that it is protected by a 1A fuse.
MSV11-Dx 64KB RAM Board (M8044)
Main document is the MSV11 -D -E User’s Manual EK-MSV1D-OP-001.
An M8044 loaded with 32 x MK4116N or MB8116E RAMs has 32KW (64KB) of RAM and is known as a MSV11-DD (“32K by 16 bits”). The handle number will be M8044-Dx (x might be an A, B or C). Note that DEC documentation typically refers to number of WORDS rather than number of BYTES.
The dipswitch settings are shown on page 2-4 of that manual. If you have 2 x MSV11-DD’s in a system, this will give you 64KW (128KB) of RAM, and the dipswitch settings will be:
- For the first board: 11111 (all on), for a starting address of 000000
- For the second board: 10111, for a starting address of O’200000 (H’10000)
Just to make things confusing, the starting address (for the dipswitches) is expressed in bytes, not words.
There are other jumpers relating to power source, RAM-chip size, and whether Bank 7 is visible. These are detailed in the manual.
More information can also be found on Willsworks pdpcards page.
MSV11 128/512KB RAM Board (M8067)
Main document is the User Guide EK-MSVOP-UG-001.
When fully populated with 4164s, the board is 512KB (256 K words by 18 bits). In this configuration it is a MSV11-PL (M8067-LA).
When fully populated with 4116s, the board is 128KB (64 K words by 18 bits). In this configuration it is a MSV11-PF (M8067-FA).
There are lots of jumpers on this board. The main ones to check are the starting address. This bloack of jumpers is about 50mm from the top of the PCB and 70mm from the right edge. For the first board in the system (Adddress Range 000-248K), there should be no junmpers in this block. For the second 512KB board, there should be a jumper from the middle pin (GND) to the bottom pin (V). This gives an Address Range of 256-504K. In either case, the next block of jumpers down (which also affect the Address Range) should not have any jumpers installed.
Hooking up a minimal PDP-11/23 system
A minimal 11/23 system that boots RT-11 V05.03 from an emulated TU58 drive can be put together using the following:
- M8186 (11/23 Processor) in the first AB position
- M8044 (64KB / 32KW RAM) in the second AB position
- M8043 (4-Port SLU) in the third AB position
- M8012 (BDV11, modified to hold 11/23 interactive boot ROMs) in the final row
- Serial Terminal connected to left-hand port of M8043 at 9600,N,8,1
- TU58 emulator (running on an MSDOS PC) connected to right-hand port of M8043 at 38400,N,8,1
I’ve found that this system will successfully boot RT-11 regardless of:
- Empty slots (without grant cards) before the BDV11, which is positioned in the final slot
- Whether the LTC is enabled or disabled on the M8186
- Whether the LTC switch is on or off on the Sigma Information Systems chassis
- Whether the left-hand switch on the BDV11 is in the left or right position
If the RT-11 boot fails part way through (before there is any sign of life at the console) at Block 164, two things that will definitely cause this are:
- No grant continuity between the M8043 and the other two cards (M8186 and M8044)
- SLU card with the vector set to anything other than 300
I have also found that at 38,400 baud, RT-11 v5.3 will boot on an 11/23 but not on an 11/03. The error reported on the 11/03 is as follows:
@10000G ?BOOT-U-I/O error 000720
The fix for this is to add the “-T” switch on the command line for tu58em. RT-11 then boots fine on the 11/03 at 38,400 baud.