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The firmware routines on the IEEE-488 interface card, can be thought of as BASIC
language extensions. The extensions consist i of the statements ABORT, CLEAR,
ENTER, ENTERA, EOL, INIT, LLO, LOCAL, OUTPUT, OUTPUTA, PPOLL,
PPOLLC, PPOLLU, REMOTE, SEND, SPOLL, STATUS, TIMEOUT, TRIGGER
and ERRPTR. These routines allow ~ the PC to execute much faster because they are
written in assembly language. Another advantage is that the statement names only
represent address offsets and these offsets may be given any name that you prefer.
Calling the routines in the firmware when using BASICA requires three steps.
1. The location of the firmware routines must be defined using a DEF SEG statement.
This statement defines the current is egment address of the firmware and it is
determined by the setting of SW2. Since the factory setting is hex D000, as
statement as following is required.
DEF SEG = &HD000
Note:
In most cases, the default setting of SW2 (hex D000) i is all right
for operation. Keep this setting unless another add-on card
occupies this memory space and cannot be changed.
2. The called routine must be located within the segment as defined by an offset
variables. For example, the OUTPUT routines has an offset of 3 and a statement to
define the offset variables is:
OUTPUT% = 3
Note:
The OUTPUT% variabLe can be other variable names.
3. The parameters needed by this routine must be defined ~' according to the require-
ment of the application. Then, the s routine is executed by using a CALL statement.
The state ments are such as:
ADDR% = 23
D$ = "F1RA"
CALL OUTPUT%(ADDR%,D$)
Additional information on the DEF SEG and CALL statements is available in your
BASIC manual.
CHAPTER 3 PROGRAMMING REFERENCE
11
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