>
> real-time task. This takes 2 write operations (1.4 uS each). I am looking for
>
> a way to access the port more quickly.
>
This is old, and "Dossy", written in Turbo-C/asm but here it is anyway........
-Wayne
#define FAST 1 // 24 mhz bus speed, min recovery time
#define SLOW 2
#define NORMAL 3 // 8 mhz bus, min recovery
#define STOCK 4 // 8mhz bus, 11clock recovery
#define BUS6 5
#define BUS8 6
#define BUS11 7
#define BUS13 8
#define BUS16 9
#define BUS22 10
/*
EISA bus speed and I/O bus cycle time tweaker functions
FAST: switches to 24mhz bus ( on 66mhz cpu) and sets the I/O recovery
time to "as sone as posible" Adjusts parameters on the H8001 and H8002
chips addressed at ports 0xc18, 0xc19 and 0xc1c and 0xc1d.
W. Wright [EMAIL PROTECTED]
*/
bus_speed( int speed )
{
switch ( speed ) {
case BUS22:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x34 // 66/3 bus speed
inc dx;
out dx, al;
}
break;
case BUS16:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x30 // 66/3 bus speed
inc dx;
out dx, al;
}
break;
case BUS13:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x2c // 66/3 bus speed
inc dx;
out dx, al;
}
break;
case BUS11:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x28// 66/3 bus speed
inc dx;
out dx, al;
}
break;
case BUS8:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x24 // 66/3 bus speed
inc dx;
out dx, al;
}
break;
case BUS6:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x20 // 66/3 bus speed
inc dx;
out dx, al;
}
break;
case FAST:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x34 // 66/3 bus speed
inc dx;
out dx, al;
mov dx, 0xc1c // use min bus cycles
mov al, 2;
out dx, al;
inc dx
mov al, 0x0c //
out dx, al;
}
break;
case STOCK:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x24 //
inc dx;
out dx, al;
mov dx, 0xc1c //
mov al, 2;
out dx, al;
inc dx
mov al, 0x04 //
out dx, al;
}
break;
case SLOW:
case NORMAL:
asm {
mov dx, 0xc18 // speed bus up
mov al, 2 // index 2
out dx, al;
mov al, 0x24 //
inc dx;
out dx, al;
mov dx, 0xc1c //
mov al, 2;
out dx, al;
inc dx
mov al, 0x0c //
out dx, al;
}
break;
} // switch
}
~
> -------------------------------------------------->-+
> C.W. Wright,[EMAIL PROTECTED], Ph:757-824-1698
> Fax: 757-824-1036,
> NASA,Goddard Space Flight Center
> Code 972, Wallops Flight Facility
> Wallops Island, Va. 23337
> -------+-<-------------------------------------------
>
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