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143847-003.Pdf iSBC® 88/25 SINGLE BOARD COMPUTER 8-Bit 8088 Microprocessor Operating at Programmable Synchronousl • 5 MHz • Asynchronous RS232C Compatible One Megabyte Addressing Range Serial Interface with Software • Selectable Baud Rates Two iSBXTM Bus Connectors • 24 Programmable Parallel I/O Lines Optional Numeric Data Processor with • • iSBC® 337 MUL TIMODULETM Processor Two Programmable 16-Bit BCD or • Binary Timers/Event Counters 4K Bytes of Static RAM; Expandable • On-Board to 16K Bytes 9 Levels of Vectored Interrupt Control, • Expandable to 65 Levels Sockets for up to 64K Bytes of JEDEC • 24/28-Pin Standard Memory Devices; • MUL TIBUS® Interface for Multimaster Expandable On-Board to 128K Bytes Configurations and System Expansion Development Support with Intel's iPDS, • Low Cost Personal Development System, and EMV-88 Emulator The iSBC 88/25 Single Board Computer is a member of Intel's complete line of OEM microcomputer systems which take full advantage of Intel's technology to provide economical, self-contained, computer-based solu­ tions for OEM applications. The iSBC 88/25 board is complete computer system on a single 6.75 x 12.00-in. printed circuit card. The CPU, system clock, read/write memory, nonvolatile read only memory, I/O ports and drivers, serial communications interface, priority interrupt logic and programmable timers, all reside on the board. The large control storage capacity makes the iSBC 88/25 board ideally suited for control-oriented applications such as process control, instrumentation, industrial automation and many others. 143847-1 September 1987 3-63 Order Number: 143847-003 infef iSBC® 88/25 FUNCTIONAL DESCRIPTION ASCII data, and iterative word and byte string manip­ ulation functions. Central Processing Unit For enhanced numerics processing capability, the iSBC 337 MULTIMODULE Numeric Data Processor The central processor for the iSBC 88/25 board is extends the architecture and data set. Over 60 nu­ Intel's 8088 CPU operating at 5 MHz. The CPU ar­ meric instructions offer arithmetic, trigonometric, chitecture includes four 16-bit byte addressable data transcendental, logarithmic and exponential instruc­ registers, two 16-bit memory base pointer registers tions. Supported data types include 16, 32, and 64- and two 16-bit index registers, all accessed by a to­ bit integer, and 32 and 64-bit floating point, 18-digit tal of 24 operand addressing modes for comprehen­ packed BCD and 80-bit temporary. sive memory addressing and for support of the data structures required for today's structured, high level languages, as well as assembly language. Architectural Features A 4-byte instruction queue provides pre-fetching of Instruction Set sequential instructions and can reduce the 750 ns minimum instruction cycle to 250 ns for queued in­ The 8088 instruction repertoire includes variable structions. The stack-oriented architecture readily length instruction format (including double operand supports modular programming by facilitating fast, instructions), 8-bit and 16-bit signed and unsigned simple, inter-module communication, and other pro­ arithmetic operators for binary, BCD and unpacked gramming constructs needed for asynchronous real­ time systems. The memory expansion capabilities MULTIIUS' SYSTEM IUS 143847-2 Figure 1. iSBC® 88/25 Block Diagram 3-64 iSBC® 88/25 offer a 1 megabyte addressing range. The dynamic Parallel I/O Interface relocation scheme allows ease in segmentation of pure procedure and data for efficient memory utiliza­ The iSBC 88/25 Single Board Computer contains 24 tion. Four segment registers (code, stack, data, ex­ programmable parallel I/O lines implemented using tra) contain program loaded offset values which are the Intel 8255A Programmable Peripheral interface. used to map 16-bit addresses to 20-bit addresses. The system software is used to configure the 110 Each register maps 64 Kby1es at a time and activa­ lines in any combination of unidirectional input/out­ tion of a specific register is controlled explicitly by put and bidirectional ports indicated in Table 1. In program control and is also selected implicitly by order to take advantage of the large number of pos­ specific functions and instructions. All Intel lan­ sible 110 configurations, sockets are provided for in­ guages support the extended memory capability, re­ terchangeable I/O line drivers and terminators, al­ lieving the programmer of managing the megabyte lowing the selection of the appropriate combination memory space, yet allowing explicit control when of optional line drivers and terminators with the re­ necessary. quired drive/termination characteristics. The 24 programmable I/O lines and signal ground Memory Configuration lines are brought out to a 50-pin edge connector. The iSBC 88/25 microcomputer contains 4 Kbytes of high-speed static RAM on-board. In addition, the Serial I/O on-board RAM may be expanded to 12 Kbytes via the iSBC 302 8 Kby1e RAM module which mounts on A programmable communications interface using the iSBC 88/25 board and then to 16 Kbytes by add­ the Intel 8251 A Universal Synchronous/ Asynchro­ ing two 4K x 4 RAM devices in sockets on the iSBC nous Receiver/Transmitter (USART) is contained on 302 module. All on-board RAM is accessed by the the iSBC 88/25 board. A software selectable baud 8088 CPU with no wait states, yielding a memory rate generator provides the USART with all common cycle time of 800 ns. communication frequencies. The mode of operation (Le., synchronous or asynchronous), data format, In addition to the on-board RAM,the iSBC 88/25 control character format, parity and baud rate are all board has four 28-pin sockets, configured to accept under program control. The 8251A provides full du­ JEDEC 24/28-pin standard memory devices. Up to plex, double buffered transmit and receive capability. 64 Kbytes of EPROM are supported in 16 Kby1e in­ Parity, overrun and framing error detection are all crements with Intel 27128 EPROMs. The iSBC incorporated in the USART. The RS232C compati­ 88/25 board is also compatible with the 2716, 2732 ble interface on each board, in conjunction with the and 2764 EPROMs allowing a capacity of 8K, 16K USART, provides a direct interface to RS232C com­ and 32 Kby1es, respectively. Other JEDEC standard patible terminals, cassettes and asynchronous and pinout devices are also supported, including byte­ synchronous modems. The RS232C command wide static and integrated RAMs. lines, serial data lines and signal ground line are brought out to a 26-pin edge connector. With the addition of the iSBC 341 MUL TIMODULE EPROM option, the on-board capacity for these de­ vices is doubled, providing up to 128 Kbytes of EPROM capacity on-board. Table1. Input/Output Port Modes of Operation Mode of Operation Unidirectional Lines Port Input Output Control <qty) Bidirectional Latched & Latched & Latched Latched Strobed Strobed 1 8 X X X X X 2 8 X X X X - 3 4 X X X(1) 4 X X X(1) NOTE: 1. Part of port 3 must be used as a control port when either port 1 or port 2 are used as a latched and strobed input or a latched and strobed output port or port 1 is used as a bidirectional port. 3-65 iSBC® 88125 Programmable Timers The outputs may be independently routed to the 8259A Programmable Interrupt Controller and to the The iSBC 88/25 board provides three independent, I/O terminators associated with the 8255A to allow fully programmable 16-bit interval timers/event external devices or an 8255A port to gate the timer counters utilizing the Intel 8253 Programmable Inter­ or to count external events. The third interval timer val Timer. Each counter is capable of operating in in the 8253 provides the programmable baud rate either BCD or binary modes. Two of these timers/ generator for the iSBC 88/25 board RS232C counters are available to the systems designer to USART serial port. The system software configures generate accurate time intervals under software each timer independently to select the desired func­ control. Routing for the outputs and gate/trigger in­ tion. Seven functions are available as shown in Ta­ puts of two of these counters is jumper selectable. ble 2. The contents of each counter may be read at any time during system operation. Table 2. Programmable Timer Functions Function Operation ISBXTM MULTIMODULETM On-Board Interrupt on When terminal count is Expansion Terminal Count reached, an interrupt request is generated. This function is Two 8-bit iSBX MUL TIMODULE connectors are pro­ extremely useful for vided on the iSBC 88/25 microcomputer. Through generation of real-time these connectors, additional on-board 110 functions clocks. may be added. iSBX MULTIMODULES optimally Programmable Output goes low upon receipt support functions provided by VLSI peripheral com­ One-Shot of an external trigger edge or ponents such as additional parallel and serial 110, software command and analog I/O, small mass storage device controllers returns high when terminal (e.g., cassettes and floppy disks), and other custom count is reached. This interfaces to meet specific needs. By mounting di­ function is retriggerable. rectly on the single board computer, less interface Rate Divide by N counter. The logic, less power, simpler packaging, higher perform­ Generator output will go low for one ance, and lower cost result when compared to other input clock cycle, and the alternatives such as MULTI BUS form factor compat­ period from one low going ible boards. The iSBX connectors on the iSBC pulse to the next is N times 88/25 provide all signals necessary to interface to the input clock period. the local on-board bus. A broad range of iSBX MUL­ TIMODULE options are available in this family from Square-Wave Output will remain high until Intel. Custom iSBX modules may also be designed Rate Generator one-half the count has been for use on the iSBC 88/25 board.
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