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4.Device Descriptor
The Device descriptor contain all that OS- -9 needs to know about a device. All device descriptors
have some basic information in common: the address of the device, the interrupt vector, level and
polling priority, which file manager to use with it (scf), what device driver to use with it (t815driv) and a
device initialization table.
Part of the device descriptor used for TIP815 mounted in slot A :
...
dc.l
$FFF58000
Address of port
dc.b
$80
Vector trap assignment
dc.b
1
IRQ hardware interrupt level
dc.b
0
IRQ polling priority
dc.b
Mode
Device mode capabilities
dc.w
FileMgr
File manager name offset
dc.w
DevDrv
Device driver name offset
dc.w
0
Device constants offset
dc.w
0,0,0,0
Reserved
dc.w
OptSiz
Option byte count
Options
dc.b
DT_SCF
Device type SCF
OptSiz
equ
*- -Options
FileMgr
dc.b
”Scf”,0
File manager
DevDrv
dc.b
”t815driv”,0
Driver module name
Mode
set
Updat_
After modifying some parameters, the device descriptor can be build with the following command:
$ make
