using the bootstrap loader
using the bootstrap loader
using the bootstrap loader
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WRITING A CUSTOM THIRD-STAGE DRIVER<br />
6.3 DEVICE INITIALIZATION PROCEDURE<br />
6-4<br />
The device initialization procedure must present <strong>the</strong> following PL/M-86 interface to <strong>the</strong><br />
third stage:<br />
device$init: PROCEDURE (unit) WORD PUBLIC;<br />
DECLARE unit WORD;<br />
END device$init;<br />
where:<br />
device$init<br />
unit<br />
(code as described below)<br />
The name of <strong>the</strong> device initialization procedure. You can choose any<br />
name you wish for this procedure, as long as <strong>the</strong> names of o<strong>the</strong>r thirdstage<br />
procedures do not conflict.<br />
The device unit number as defined during Bootstrap Loader<br />
configuration.<br />
The WORD value returned by <strong>the</strong> procedure must be <strong>the</strong> device granularity, in bytes, if <strong>the</strong><br />
device is ready, or zero if <strong>the</strong> device is not ready.<br />
The third-stage device driver initialization procedure, (like <strong>the</strong> first-stage device<br />
initialization procedure) must do <strong>the</strong> following operations:<br />
1. Test to see if <strong>the</strong> device is present. If <strong>the</strong> device is not present, return <strong>the</strong> value zero.<br />
2. Initialize <strong>the</strong> device for reading. This is a device-dependent operation. For guidance<br />
in initializing <strong>the</strong> device, refer to <strong>the</strong> hardware reference manual for <strong>the</strong> device.<br />
3. Test to see if device initialization was successful. If it was not, return <strong>the</strong> value zero.<br />
4. Read <strong>the</strong> device volume label to obtain <strong>the</strong> device granularity. (For information on<br />
<strong>the</strong> location and organization of <strong>the</strong> volume label, see <strong>the</strong> iRM)(® Disk Verification<br />
Utility Manual.)<br />
5. If <strong>the</strong> attempt to obtain <strong>the</strong> device granularity was successful, return <strong>the</strong> device<br />
granularity. O<strong>the</strong>rwise, return <strong>the</strong> value zero.<br />
NOTE<br />
Besides <strong>the</strong> above five steps, <strong>the</strong> procedure must follow MUL TIBUS II<br />
transport protocol and belong to <strong>the</strong> BSL-Drivers COMPACT sub-system if <strong>the</strong><br />
driver functions in a MULTIBUS II environment. Refer to Section 5.5 for<br />
more information on <strong>the</strong>se two requirements.<br />
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