DELQA — QBUS Ethernet controller
The DELQA (M7516) is DEC’s Ethernet controller for the QBUS. QUniLator
presents its register file, its buffer descriptor lists and its interrupt to the
processor as the card does, and moves the frames to and from the board’s own
network, so the machine stands on the LAN with an Ethernet address of
its own. It is listed as delqa, of type DELQA.
2.11BSD on an MSCP disk, on the LAN puts a real PDP-11/53 on the network through it, step by step.
What the machine sees
Section titled “What the machine sees”| Registers | Eight words at 17774440, the address of the first Ethernet controller: the station address PROM in the first six, which also take the receive and transmit list addresses, then the vector address register and the CSR |
| Mode | A DELQA in normal mode, which a driver may switch to the DEQNA register model. With deqna_lock set it is a DEQNA from power-up |
| Station address | mac, read out of the address PROM. Each board has its own, starting 08:00:2b |
| Interrupt | BR4, at the vector the driver writes into the vector address register. Until a driver writes one, the controller does not interrupt |
| Transfers | Frames and descriptor lists move by DMA, over the full 22-bit QBUS address space |
| Network | The board’s interface interface, veth-pdp unless set otherwise |
The vector is the driver’s to choose, as on the card, so intr_vector takes no
setting on this device.
Using it
Section titled “Using it”- Add
delqaon the Configurations screen. The defaults suit a first Ethernet controller and need no change. - Enable it. The controller attaches to
veth-pdpand the machine’s driver finds it at 17774440.
The board joins veth-pdp to the bridge that carries its own Ethernet, so the
machine reaches every host on the LAN, DEC multicast included, and the board
itself. interface and deqna_lock are read when the controller is enabled; to
change one, disable the controller, change it, and enable it again.
Its address on the network
Section titled “Its address on the network”The bridge works at the Ethernet level, so the machine is a host of its own on
the LAN, beside the BeagleBone, with its own station address from mac. It
needs an IP address of its own, in the same subnet as the BeagleBone’s, with
the same netmask and gateway. That address must not be the BeagleBone’s, and
it must not be one the DHCP server can hand out. Pick a free address outside
the DHCP pool and set it in the guest; a PDP-11 operating system has no DHCP
client. The alternative is a reservation in the DHCP server for the station
address, so the server never gives that address to anything else.
For DEC’s diagnostic, set loopback: the controller then behaves as one with a
loopback connector on its transceiver port, and is off the network until it is
cleared.
What has been verified
Section titled “What has been verified”- DEC’s DELQA diagnostic CZQNA (
ZQNAJ0.BIC, the DEQNA-DELQA-DESQA functional test on the XXDP 2.5 pack) passes with no errors on a QBone, run withloopbackset and answering Y to “Test in External Loop Back Mode”. Test 15 needs a processor strapped for power-up mode 0 and is skipped. - 2.11BSD on a real PDP-11/53 attaches it as
qe0, goes multi-user on the LAN, and answerspingandtelnetfrom other hosts. - RSX-11M-PLUS V4.6 brings its DECnet line
QNA-0up on it and sends DECnet router hellos and MOP loopback frames onto the LAN.
Parameters
Section titled “Parameters”Settings
Section titled “Settings”What a configuration stores and an operator sets.
| Parameter | Short | Value | Default | What it is |
|---|---|---|---|---|
interface | if | text | veth-pdp | host Ethernet interface shared with the emulated controller |
mac | text | derived from the board’s Ethernet address | station address, 6 hex bytes separated by ”:” or ”-” | |
activityled | al | number | 3 | Number of the LED used for activity display. |
deqna_lock | dl | 0 or 1 | 0 | DEQNA-lock mode: emulate a DEQNA (for RSTS/E and other DEQNA-only drivers) |
loopback | lb | 0 or 1 | 0 | loopback connector installed on the transceiver port |
Status
Section titled “Status”What the device reports as it runs. A configuration does not store these.
| Parameter | Short | Value | What it is |
|---|---|---|---|
activitylamp | actl | 0 or 1 | State of activity lamp |
It also carries the parameters under parameters every card on the bus has.
In detail
Section titled “In detail”interface
Section titled “interface”The board’s network interface the controller is attached to. veth-pdp is the one the QUniLator package creates for an emulated controller: its other end is joined to the bridge br0 together with the board’s own eth0, so the machine reaches both the LAN and the board itself. A raw attachment to the uplink reaches the LAN but cannot reach the board it runs on, which is why the controller has an interface of its own. Read when the controller is enabled; an interface that is not there yet is tried again every two seconds until it appears.
The station address the address PROM gives the driver: six hex bytes separated by : or -. Each board derives its own the first time - DEC’s prefix 08:00:2b and the low three bytes of the board’s own Ethernet address - and keeps it in delqa.mac in the board’s state directory (/var/lib/qunilator), so it stays the same across boots and differs from board to board. A value set here overrides it and is stored with the configuration. A multicast address (low bit of the first byte set) is refused. Change it while the controller is disabled.
activityled
Section titled “activityled”Which of the board’s four activity LEDs, 0 to 3, traffic lights; 4 or more lights none. Drives take the LEDs by unit number, so 3 keeps the controller clear of a machine with one drive.
activitylamp
Section titled “activitylamp”On while frames move in either direction, held a moment past each frame so the web interface sees it.
deqna_lock
Section titled “deqna_lock”The DEQNA-lock switch on the board. On, the controller powers up as a DEQNA and stays one, whatever a driver writes to the vector register, which is what RSTS/E and other DEQNA-only drivers need. Off, it powers up as a DELQA, and a driver that clears the mode bit in the vector register switches it to the DEQNA register model itself. Can be changed only while the controller is disabled.
loopback
Section titled “loopback”A loopback connector plugged into the transceiver port, as DEC’s diagnostics ask for. Every frame the controller transmits comes straight back to its own receiver and shows as carrier in the CSR while it passes; the network is disconnected in both directions. Set it to run the external loopback tests of the CZQNA diagnostic, and leave it off for a machine on the network. It takes effect at once.