Intel mcs-48 User Interrupt causes an Interrupt only If, Prompt system Is running a user program

INTELLEC PROMPT 48

Documentation

The PROMPT 48 manual Includes chapters for the reader with little or no programming experience. Topics treated range from number systems to microcomputer hardware design. A novel, unifying set of tutorial diagrams - MICROMAPS - simplify microcomputer

concepts. PROMPT's handy, pocket-sized reference card let can be affixed to the mainframe. Programming pads aid in the organization and documentation of pro- grams. These features, plus a comprehensive design library of manuals, articles, and application notes, make the Intellec PROMPT 48 ideal for the newcomer to mlcrocomputlng.

SPECIFICATIONS	User Interrupt - causes an Interrupt only If the
	PROMPT system Is running a user program.

Timing

Basic Instruction - 2.5 ,..s

Cycle Time - tCY = 2.5,..s

Clock - 6 MHz ± 0.1%

Memory Bytes

The 8748 contains 64 bytes of register memory, no ex- ternal data memory, and 1024 bytes of RAM program memory. The PROMPT system provides 256 bytes of ex- ternal data memory, and 1024 bytes of RAM program memory. PROMPT RAM program memory can be used in place of the on-chip EPROM program memory; thus programs less than 1024 bytes may be designed. For larger programs additional memory can be directly In- terfaced to the MCS-48 bus via the PROMPT panel I/O ports and bus connector.

Memory Configuration

Memory	Maximum	On Chip	In PROMPT 48
Reglsler	64	64	0
Dala	3328	0	256
Program	4006	1024 EPROM	1024 RAM

1/0 Ports

All MCS-48 I/O ports are accessible on the PROMPT panel connector.

Bus - A true bidirectional 8-bit port with associated strobes. If the bidirectional feature is not needed, bus can serve as either a statically latched output port or a non-latching Input port. Input and output lines cannot be mixed.

Ports 1 and 2 - Data written to these 8-bit ports is latched and remains unchanged until written. As Inputs these lines are not latching. The lines of ports 1 and 2 are called quasi bidirectional. A special output structure allows each line of port 1 and half of port 2 to serve as an input, an output, or both. Any mix of input, output, and both lines is allowed.

TO, n, and INT - Three pins that can serve as Inputs. TO can be designated as a clock output. Input/output can be expanded via the PROMPT panel connector with a special I/O expander (8243) or standard peripherals.

Reset and Interrupts

Relit - Initializes the PROMPT system and enters the monitor.

Monitor Interrupt - exits a user program gracefully, preserving system status and entering the monitor.

The processor traps to location 316. The MCS-48 timer/- event counter is not used by the PROMPT system and is available to the user. Either timer flag or interrupt will signal when overflow has occurred. The timer interrupt can be used only in the go-no-break (real time) mode.

EPROM Programming

PROMPT 48 provides a programming socket to directly program 8748s. Programs are loaded Into the PROMPT RAM program memory via keyboard. EPROM, teletype- writer, or other serial interface. A fail-safe interlock ensures programming pulses are applied only if the device is properly inserted. Inadvertant reprogramming is prevented by a read-before-write programming algo- rithm. Each location may be individually programmed, one byte at a time.

Panel 1/0 Ports and Bus Connectors

All MCS-48 pins, except five, are accessible on the I/O ports and bus connector. The five reserved for PROMPT system control are EA external access, SS single step, X1, X2 crystal Inputs, and 5V. Due to internal buffering of the MCS-48 bus, access times will be negligibly degraded by the PROMPT system. Since MCS-48 pro- cessors do not communicate internal address gate status, bus data must be driven out If neither PSEN nor RD is asserted.

System Devices'

Both user programs and the PROMPT monitor enjoy ac- cess to system devices: serial I/O, panel displays, and keyboard. These are memory-mapped to program memory addresses beyond 2K.

Serial I/O - The serial I/O port (data 82016 , control 821 16) Is defined by software and jumpers for 110 baud, 20 mA current loop, but can easily be jumpered for other baud rates and RS232C levels. Asynchronous or synchronous transmission, data format, control characters, and par- ity can be programmed.

Panel Displays - Eight display ports (data 810-8171slallow each of the panel displays to be written from user programs. Data written on a display device will time out after a fixed interval. Displays must be refreshed on a polled or interrupt-driven basis. User programs can call software drivers which provide this capability.

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