dr(4) [bsd man page]
DR(4) Kernel Interfaces Manual DR(4) NAME
dr - DR11-W general purpose interface driver SYNOPSIS
/sys/conf/SYSTEM: NDR dr11-w_units # DR11-W /etc/dtab: #Name Unit# Addr Vector Br Handler(s) # Comments dr ? 172410 124 5 drintr # dr11-w (b-bus emulator) dr ? 172430 130 5 drintr # dr11-w (gc-bus emulator) dr ? 172450 134 5 drintr # dr11-w (em-2 interface) major device number(s): raw: 12 minor device encoding: bits 0007 specify DR unit DESCRIPTION
The Digital Equipment 1981-82 Peripherals Handbook states the following about the DR11-W: The The DR11-W is a general purpose, direct memory access (DMA) interface to the PDP-11 UNIBUS or VAX UNIBUS. The DR11-W moves data directly between memory and the UNIBUS to and from the user's peripheral. It features: o Word or byte transfers. o Programmed or direct memory access (DMA) block transfers. o Burst data transfers. o User-controlled transfer rates up to memory speed. The DR11-W is a 53-line direct memory access (DMA) interface to the PDP-11 UNIBUS or VAX UBA, which allows the user to control data transfers between the host processor and a peripheral. The DR11-W has 32 data lines (for transferring 16-bit parallel data) and 21 control lines (for transferring control and status information. When used as an interprocessor buffer (IPB), the DR11-W allows data transfers between two processors. Interprocessor communication is accomplished by attaching one DR11-W to each processor UNIBUS or UBA and then cabling the two DR11-Ws together. There. Now you know as much about it as I do. A number of ioctl(2) calls apply to the dr devices, and have the form #include <pdpuba/drreg.h> ioctl(fildes, code, arg) int *arg; The applicable codes are: DRGTTY Get DR11-W status. DRSTTY Set flags and function. DRSFUN Set function. DRSFLAG Set flags. DRGCSR Get CSR and WCR. DRSSIG Set signal for ATTN interrupt. DRESET Reset DR11-W interface. DRSTIME Set timeout. DRCTIME Set timeout inactive. DROUTPUT Put word in output data register. DRINPUT Get word from input data register. DRITIME Don't ignore errors on timeout. FILES
/dev/dr[0-7] device special files /dev/MAKEDEV script to create special files /dev/MAKEDEV.local script to localize special files SEE ALSO
dtab(5), autoconfig(8) DIAGNOSTICS
dr%d: error csr=%b, eir=%b dr%d: timeout error BUGS
This interface is only available under 2.9BSD and 2.11BSD. No documentation exists on how to use it. 3rd Berkeley Distribution January 27, 1996 DR(4)
Check Out this Related Man Page
EN(4) Kernel Interfaces Manual EN(4) NAME
en - Xerox 3 Mb/s Ethernet interface SYNOPSIS
/sys/conf/SYSTEM: NEN en_controllers # Xerox prototype (3 Mb) Ethernet DESCRIPTION
The en interface provides access to a 3 Mb/s Ethernet network. Due to limitations in the hardware, DMA transfers to and from the network must take place in the lower 64K bytes of the UNIBUS address space, and thus this must be among the first UNIBUS devices enabled after boot. Each of the host's network addresses is specified at boot time with an SIOCSIFADDR ioctl. The station address is discovered by probing the on-board Ethernet address register, and is used to verify the protocol addresses. No packets will be sent or accepted until a network address is supplied. The interface software implements an exponential backoff algorithm when notified of a collision on the cable. This algorithm utilizes a 16-bit mask and the VAX-11's interval timer in calculating a series of random backoff values. The algorithm is as follows: 1. Initialize the mask to be all 1's. 2. If the mask is zero, 16 retries have been made and we give up. 3. Shift the mask left one bit and formulate a backoff by masking the interval timer with the mask (this is actually the two's complement of the value). 4. Use the value calculated in step 3 to delay before retransmitting the packet. The interface handles both Internet and NS protocol families. It normally tries to use a ``trailer'' encapsulation to minimize copying data on input and output. The use of trailers is negotiated with ARP. This negotiation may be disabled, on a per-interface basis, by set- ting the IFF_NOTRAILERS flag with an SIOCSIFFLAGS ioctl. DIAGNOSTICS
en%d: output error. The hardware indicated an error on the previous transmission. en%d: send error. After 16 retransmissions using the exponential backoff algorithm described above, the packet was dropped. en%d: input error. The hardware indicated an error in reading a packet off the cable. en%d: can't handle af%d. The interface was handed a message with addresses formatted in an unsuitable address family; the packet was dropped. SEE ALSO
intro(4N), inet(4F) BUGS
The device has insufficient buffering to handle back to back packets. This makes use in a production environment painful. The hardware does word at a time DMA without byte swapping. To compensate, byte swapping of user data must either be done by the user or by the system. A kludge to byte swap only IP packets is provided if the ENF_SWABIPS flag is defined in the driver and set at boot time with an SIOCSIFFLAGS ioctl. 3rd Berkeley Distribution August 20, 1987 EN(4)