I N T R O D U C T I O N; C O M M A N D Parsing; I N P U T / O U T P U T Port Configuration; O U T P U T Port Reset Polarity - Racal Instruments 7064 Instruction Manual

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SECTION 3 B R E A D B O A R D OPERATION

3.1 I N T R O D U C T I O N

There are two methods of controlling user-defined circuitry on the breadboard area. The

first way is to use the upper half of the 68000 address space and the appropriate software

tools. The second and easier approach is to use the 96 buffered I/O lines available on the

breadboard card. This section discusses the latter approach.

For more complex programming, the user may download user-defined code which can run

interactively with the local command set. This is described in more detail in Section 4.

User-defined commands can easily be added and used in conjunction with the local

command set of the breadboard. When a command is sent to the 7064 using word serial

protocol, it is received and parsed by the command parser. I f the command matches a

command from the local command set, the appropriate routine is called. I f no matching

command is found (user-defined command), the command is placed in the secondary input

queue. The user routine called from the main loop will then retrieve the characters from

the secondary input queue and parse for their own commands. The nvsetvect command

can be used to allow the 7064 parser to be bypassed, allowing the users parser to take

control of the 7064. I f there are no main loop user routines, the main loop generates an

error for the characters placed in the secondary queue. This and other complex tasks are

described in more detail in Section 4.

A set of local commands are available to the user to allow for the control of the user-

defined circuit through the twelve I/O ports available. This section describes the control

of these lines.

The 7064 breadboard has twelve 8-bit ports. Each Port can be individually configured

for input or output. Three lines are supplied for the user to control the type of port and

its operation. The port outputs are designed to accept a 14-pin dual-in-line connector for

the user to easily wire into the breadboard area.

All outputs are set to a known level during reset. T h e user can select whether all the

outputs will be set to a logic 1, or all outputs will be set to a logic 0 by simply doing the

following:

3-1

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