92200 Micro-Link VME200 Single Board Computer

The Micro-Link's VME200 single board computer is an advanced, highly integrated VME bus computer. By making use of VLSI CMOS technology, the VME200 provides a fully featured SBC in a compact, low power package.

At the heart of the card is the Motorola MC68306 microprocessor. This CPU incorporates the industry standard MC68000 CPU and MC68681 Dual UART with system integration functions including a DRAM controller, programmable address decoding, interrupt handling, and I/O ports. The internal 32 bit address bus allows the VME200 to expand memory beyond the 16 Mbytes limit of the 68000.

The on-board memory is easily configured to suit most applications, using a combination of four 32 pin Bytewide memory sockets and dual banks of low cost, zero wait state DRAM. Software controlled registers independently determine the address base, size, wait states, and read/write protection for each memory block.

One pair of Bytewide sockets accepts up to 2 Mbytes of EPROM/ROM, or 1 Mbytes of FLASH EPROM, which may be reprogrammed in place. The other pair of Bytewide sockets provides these facilities, but can also accept up to 1 Mbytes of SRAM. The SRAM may be battery backed using the on-board battery. Dynamic memory is optional, and populations of 512 Kbytes 1, 2, 4 Mbytes are available.

Two independent asynchronous serial communications channels are provided. Standard data formats and data rates (up to 38,400 BPS) are supported, with hardware input and output handshake. Line interface for RS-232 (single ended) and RS-422/485 (differential) are provided on both channels; interface selection is under software control, and may be changed at any time.

The RS-232 drivers include DC/DC converters operating from +5V, eliminating the need for a system +/- 12V supply. The RS-485 drivers can be used in bussed configurations with up to 332 drivers sharing a line. The DUART includes an address matching mode, permitting simple implementation of small communication networks.

The optional calendar clock maintains year, month, day,hour, minute, second, and fraction of seconds down to 1/100th. It includes an alarm, 64 bytes of RAM, and may be programmed to record the exact time of a system power failure. The SRAM and calendar clock may be battery backed with an on-board battery. Power up and power fail circuitry ensures reliable operation.

Ten independently maskable interrupt sources, including all VME bus interrupts, DUART, timer, and abort switch, are mapped to seven interrupt levels. Each level may be programmed for vectored or auto-vectored response. On-board bus timeout and software watchdog are included. The front panel includes reset and abort switches, a green LED indicator for CPU activity, and a red LED under software control.

The VME200 is fully compliant with the VME bus Rev C specification. It includes a VME bus system controller, A24;D16 and A16;D16 bus master, and multilevel interrupt handler. The selectable VME bus Slot One System controller includes VME bus power up and pushbutton system reset driver, single level bus arbiter, system clock driver, interrupt daisy chain driver, bus activity watchdog and bus error driver.

Power management has been a major design factor with the VME200. The use of CMOS devices and +5V only operation throughout minimizes the board and system power supply requirements and reduces heat generation, cooling requirements, and enhances reliability.