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The bit manipulation commands let the user directly set or reset a bit without
having to keep a image of the byte in the user's program. When a bit is set
or reset, the rest of the bits in the byte are not affected but all of the bits in
the byte become output bits. Bits can be sensed or read individually. When
a bit is read, all of the bits in the byte become input bits. Ports used with the
bit manipulation commands are not configured as input or output ports.
Direct data transfer to a specific port is performed with the SENSE and
SOURCe PORTn commands. These ports are not configured as input or
output ports. Data transfer can be a decimal or hex value and data polarity
can be set on a bit-by-bit basis.
To output data as strings, the user configures one or more byes as output
bytes, sets the data polarity and listen format. If handshaking is disabled,
the unit will accept character strings at its GPIB or serial interface, convert
the characters into digital bits, set the output latches and generate the data
strobe pulse. Listen data can be hexadecimal characters (0-9, A-F), the
ASCII number subset (0-9 and :<=>?), decimal values that represent the
sum of the binary bits in a byte, or binary bytes (4863 only). If listen
handshaking is enabled, data transfer will only occur if the Status A input
signal is in its logic true state. Data overrun is be reported as an Execution
Error.
To input data as a string, the user configures one or more bytes as input
bytes, sets the data polarity and talk format. If handshaking is disabled, the
unit will simply input the digital data when addressed to talk or when
queried, convert it into the selected format, append the EOM character and
output the data on the GPIB bus or serial interface. If talk handshaking is
enabled, data transfer will occur if the EDR (External Data Ready) signal
is received and the unit has been addressed to talk. The unit must be
UNTALKed between transparent data transfers. If queried by a
command and the EDR signal is not received, the 4863 will report an
Execution Error. The external device must hold the digital inputs stable
until the 4863 drops its Inhibit line. The talk data may be a series of
hexadecimal characters, routed through an arbitrary Hex-to-ASCII conver-
sion table, or as a series decimal values that represent the binary sum of the
logic '1' bits in each input byte.
The 4863 uses its IEEE-488.2 Status Reporting Structure to generate
Service Requests (SRQs) if the EDR bit becomes set or the Status inputs
