MODEL 1710 VQUHI

VME bus-QBUS-UNIBUS-HOST INTERFACE

FEATURES

Transfers between VMEbus and host computer memory are by DMA at maximum host bus speeds (250K wps on QBUS machines and 500K wps on UNIBUS).
VMEbus system controller functions may be enabled or disabled.
VMEbus master capable of A32, A24, A16, D16, D8 transfers.
VMEbus interrupt handler which serves and buffers multiple interrupts from VMEbus.
Read/Modify/Write capability by the host to VMEbus devices.
Automatic conversion of byte ordering between host and VMEbus. This feature may be modified or disabled by programmable byte and word swap bits.

APPLICATIONS

Simple but versatile interface between DEC, Qbus or Unibus computer and VMEbus crate.
DEC computer interface to VME to VME based CAMAC Branch Driver and Serial Driver.

GENERAL DESCRIPTION

This single-width (6U) VME-based Qbus/Unibus Host Interface module (VQUHI) is designed to provide a relatively simple but versatile interface between a DEC, Qbus or Unibus computer and a VMEbus crate. The hardware required in the DEC computer is a standard DRV11-WA-DMA model for a Qbus machine or a standard DR11-WDMA model for a Unibus machine. The hardware required in the VMEbus crate is this single 6U module connected to the host via two 40-conductor shielded ribbon cables. The host software consists of standard DEC device drivers linked to users applications. No software is required in the VQUHI.

The Bi Ra Model 1710 (VQUHI) may be used as a slot one VMEbus system controller or the system controller functions may be disabled by a switch in the module. The disabling of the system controller function allows more than one host to share a VMEbus crate or a different VMEbus system controller module to be used. All transfers to and from VMEbus devices are directly controlled by the DEC host computer. Devices on the VMEbus don't have access to the host computer's bus except by interrupt. VMEbus devices may interrupt the host computer using normal VMEbus interrupt. Multiple VMEbus interrupt vectors are stored in a FIFO in the VQUHI until serviced by the host computer.

CONTROL AND STATUS

There are two levels of control and status: The DRV11-WA or DR11W registers. The VQUHI registers.

The host communicates directly with the DR registers via software. The VQUHI module in the VMEbus crate is a I/O device and the host communicates with its registers via the DR module. A microcoded sequencer on the VQUHI monitors the interface to the DR module and theVMEbus interrupt lines. The sequencer decodes the function commands from the host and executes routines to carry out the commands. Interrupts from VMEbus have priority over commands from the host and will be serviced as soon as possible, even the middle of a DMA transfer between the host and VMEbus.

STATUS LIGHTS

The front panel LEDs on the VQUHI provide visual status of module activity. The LEDs are "stretched" to ensure that even such as VME master cycles are visible.

SYSCON	The VMEbus controller function is enabled by switch
MASTER	The VQUHI is doing a VMEbus data transfer
BERR	VMEbus error has occurred (not latched)
INTERRUPT	VMEbus interrupts have been serviced and are in FIFO

BLOCK DIAGRAM

Shown below are the two modules required for the DEC computer to VMEbus interface. On the DEC computer end is a standard DRV11-WA DMA module for a Qbus machine or a standard DR11-WDMA for Unibus machine. The DEC modules are linked to the VQUHI VMEbus controller module via two 40-conductor shielded ribbon cables.

VMEBUS MASTER INTERFACE

As a VMEbus master, the VQUHI follows IEEE 1014-87 specs. The VMEbus master interface consists of the following:

Programmable VMEbus address modifiers

32-bit VMEbus address counter

16-bit data port (byte or word transfer)

Byte and word swappign performs

host/VMEbus byte ordering conversions

The VMEbus address modifiers get programmed by the host allowing it to specify short, standard or extended addressing. Any address modifiers are allowed and the programmer is responsible for using valid ones.

VMEBUS INTERRUPT HANDLER-AND INTERRUPT VECTOR FIFO

The VMEbus interrupt handler provides a means for VMEbus interrupt modules to interrupt the host.

DIP switch for selecting any or all 7 VMEbus interrupts for servicing

Interrupts automatically

Host interrupted when vectors are in FIFO, module is idle, and DRV interrupts are enabled.

Any or all VMEbus interrupt levels can be enabled by the user via a 7-bit DIP switch on the module. Interrupt servicing uses VMEbus mastership at the same priority as selected by the user with the bus priority jumper.

VMEBUS SYSTEM CONTROLLER

The system controller on the VQUHI, when enabled, provides the following functions:

16MHz System Clock
Bus Timer
Round Robin or Priority Bus Arbiter (switch selectable)
Power up RESET of VMEbus

Every VMEbus crate requires a module in slot one that performs the function of system controller. The VQUHI module contains system circuity which may be enabled or disabled by a switch mounted on the PC board. Some systems may use more than one VQUHI to allow more than one host computer to share the same VMEbus. In this case, one of the VQUHI modules will occupy slot one and have its system controller functions enable while the other(s) will occupy other slots and have their system controller functions disabled. Alternatively, another type of module, such as a CPU, may be used as a system controller and all VQUHI modules would have their system controllers disabled.

WEIGHT

.70kg (1 lb. 8oz.)

ORDERING INFORMATION:

Model 1710 VMEbus-Qbus-Unibus-Host Interface

ACCESSORIES:

Model DRV11-WA-DMA Module for Qbus machine
Model DRV11-W DMA module for Unibus machine
Model 40 conductor shielded ribbon cables (2ea. required)

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