BIT3 MODEL 403
Adapter connects an IBM PC/AT computer to a VMEbus system
Bit 3's Model 403 Adaptor connects an IBM PC/AT computer to a VMEbus system for fast, cost-effective sharing of memory and special purpose boards. The Model 403 Adaptor provides high-speed data transfers between the PC/AT bus and VMEbus, and requires minimal software support.
Model 403 interconnects the PC/AT and VMEbus at the physical layer. Working at the lowest level, the bus, the Adaptor allows the two systems to share memory; memory appears to and is treated by each system as if it were its own. In addition, a card only available on one bus may be accessed and directly controlled by a device on the other bus. For example, an Array Processor board in the VMEbus chassis can be directly controlled by the PC/AT processor.
The Model 403 Adaptor uses Memory Mapping for inter-system communications. Memory Mapping controls random access (PIO transfers) to VMEbus address space and dual-port memory. It provides an easy-to-use interface with low overhead that permits two processors to communicate via 8-bit and 16-bit random access memory reads and writes. The PC/AT system can access up to 16M bytes of VMEbus system memory through a window in the PC/AT's address space.
With the Bit 3 Adaptor, each bus operates asynchronously and independently. The buses are linked only when a memory or I/O reference is made to an address on the PC/AT system that translates to a reference on the VMEbus system. The integrity of the interface between the Adaptor cards is maintained by parity checks on address, control, and data lines.
The Adaptor functions as a slave PC/AT device allowing memory references to it to pass to the VMEbus chassis. Although the VMEbus cannot directly address the PC/AT, data can be passed by VMEbus masters to and from the PC/AT via an optional shared Dual Port RAM card.
Other Bit 3 Adaptors, supporting a wide variety of buses, can be used with Model 403 Adaptors to connect multiple computers and systems in star, daisy-chain or modified star/daisy-chain configurations.
COMMUNICATION BETWEEN SYSTEMS
The Model 403 Adaptor supports Memory Mapped inter-system communication. Memory Mapping controls random access to VMEbus RAM, dual-port memory, and VMEbus I/O.
Memory Mapping provides an easy-to-use, flexible interface with low overhead that permits two processors to communicate via 8-bit and 16-bit random-access memory reads and writes. The PC/AT computer can access up to 16M bytes of memory in the VMEbus system through a window in the PC/AT bus address space.
Memory Mapping permits high-speed random access 8-bit and 16-bit writes from the PC/AT to the VMEbus bus at speeds comparable to reads and writes to local memory. Programmable I/O registers, loaded at system boot, establish the resulting host and destination address ranges in address space.
Two Memory Mapping techniques are supported: Direct Mode (with address biasing) and Page Mode. Either technique may be used to control access to VMEbus memory. Direct Mode is used to access dual-port memory. Access to VMEbus I/O is not affected by mapping mode.
Direct Mode has a one-to-one relationship between address windows. Data are transferred through one window directly into an equal size window on the other bus. Window size is configured via jumper settings. The addressing range can be as large as 14.8M bytes (15M bytes extended minus 128K bytes system space).
In Page Mode, a 32K - 1M byte window in PC/AT bus address space is coupled with programmable registers that provide the upper bits for the VMEbus address. The lower bits of the VMEbus address come directly from the PC/AT. Thus, the PC/AT can access up to 16M bytes of memory in the VMEbus system by paging through the VMEbus system's address space.
Data transfers are either 8-bit bytes or 16-bit words for both memory and I/O cycles. Round trip cycle time from the PC/AT to the VMEbus and back is 2 usec. If 16-bit words are transferred, the data rate is 1M Byte/sec.
Memory Mapping also controls access to dual-port memory. Dual Port RAM is an optional card installed on the VMEbus Adaptor card. Dual Port RAM provides a memory buffer; saves the cost of additional memory cards; and requires no additional VMEbus card slots.
Optional Dual Port RAM provides shared memory space accessible by random access reads and writes from either system. Dual Port RAM access uses only the bandwidth of the accessing bus. Consequently, data can be exchanged with minimal impact on the performance of the other system's bus. Both systems can access Dual Port RAM simultaneously; the Adaptor arbitrates accesses.
Recommended Dual Port RAM cards now available from Bit 3 for Model 403 include: 32K, 128K, 1M, 2M, and 4M byte cards.
INTERRUPT AND ERROR HANDLING
Model 403 supports interrupts from three sources:
An Adaptor card control register provides PC/AT acknowledgment of VMEbus interrupts and vector passing.
VMEbus SYSTEM CONTROLLER CAPABILITY
In addition to VMEbus control and bus master capabilities, the Model 403 Adaptor can function as the VMEbus system controller. If the VMEbus system is to be used primarily as an expansion chassis for slave VMEbus cards, this feature saves the expense of an additional VMEbus system controller.
If configured as the system controller, the VMEbus Adaptor card provides level 3 bus arbitration, the VMEbus system clock and system reset.
32K BYTE WINDOWS
OTHER FEATURES
TECHNICAL HIGHLIGHTS
The VMEbus Adaptor card draws 4.5A at 5V. The PC/AT Adaptor card draws 3.0A at 5V.
Temperature: 0 - 60 degrees C operating; -40 - 85 degrees C storage. Humidity: 0% - 90% non-condensing.
REQUIRED COMPONENTS
Each Model 403 package contains: one PC/AT Adaptor card, one VMEbus Adaptor card, a Utilities Diskette and a manual. A cable is required but is ordered separately so that you can specify the appropriate length for your installation.
OPTIONS
32K byte Model 400-201 128K byte Model 400-202 1M byte Model 400-203 2M byte Model 400-204 4M byte Model 400-205
8' Round EMI-Shielded Model 400-105 25' Round EMI-Shielded Model 400-106
Bulkhead connector configurations (contact Bit 3 for configurations)
Two Fiber Card Model 400-5 Two Fiber Module Model 400-50
(Fiber-Optic Cards are for the VMEbus system only; Modules may be used with either the PC/AT or VMEbus system. Two Fiber-Optic Interfaces are required. For more information, request the Model 400 Fiber-Optic Interface data sheet.)
High-quality, OFNP-grade, 62.3/125 micron glass duplex cable with tight buffer construction and ST-style connectors; standard cables are 5 meters (approximately 16') in length; custom lengths up to 2 km are available.