using the bootstrap loader
using the bootstrap loader
using the bootstrap loader
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USING THE BOOTSTRAP LOADER<br />
2-6<br />
Although <strong>bootstrap</strong> loading usually occurs in response to an external event (such as a<br />
system reset or a monitor command), an executing program can also initiate it. Such a<br />
program can load ano<strong>the</strong>r system by calling <strong>the</strong> PUBLIC symbol BOOTSTRAP_ENTRY.<br />
To prepare for such a call, do <strong>the</strong> following:<br />
1. Define BOOTSTRAP_ENTRY as an EXTERNAL symbol in <strong>the</strong> code of <strong>the</strong><br />
invoking program.<br />
2. Place a call to BOOTSTRAP_ENTRY in <strong>the</strong> code of <strong>the</strong> invoking program. The<br />
form of <strong>the</strong> call is<br />
where:<br />
CALL BOOTSTRAP _ ENTRY(@filename)<br />
filename An ASCII string containing ei<strong>the</strong>r <strong>the</strong> pathname of <strong>the</strong><br />
target file followed by a CARRIAGE RETURN, or a<br />
CARRIAGE RETURN only. If <strong>the</strong> string contains a<br />
pathname, <strong>the</strong> named file is loaded. If <strong>the</strong> string<br />
contains a CARRIAGE RETURN only, <strong>the</strong> default file,<br />
as defined by <strong>the</strong> %DEFAULTFILE macro in <strong>the</strong><br />
BS1.A86 or BSIMB2.A86 configuration file, is loaded.<br />
(Chapter 3 describes <strong>the</strong> BS1.A86 and BS1MB2.A86<br />
files.)<br />
The call must follow <strong>the</strong> PL/M-86 LARGE model of segmentation. (Even though<br />
this is a call, ra<strong>the</strong>r than a jump, it does not return.)<br />
3. Link <strong>the</strong> calling program to a version of <strong>the</strong> first stage of <strong>the</strong> Bootstrap Loader. You<br />
can do this by <strong>using</strong> <strong>the</strong> BS1.CSD file as a model and making <strong>the</strong> following changes:<br />
• Add <strong>the</strong> calling program to <strong>the</strong> list of modules that are linked in BS 1.CSD.<br />
• "Comment out" <strong>the</strong> locate sequence if you want to use any code o<strong>the</strong>r than<br />
absolute code. To comment out a line, precede it with a semicolon. For more<br />
details on absolute code, refer to <strong>the</strong> iAPX 86,88 Family Utilities Guide.<br />
Refer to Chapter 3 for more information on <strong>the</strong> BS 1.CSD file.<br />
Bootstrap Loader