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3.1 About the BIOS
The BIOS (BasicInput/Output
System) functions represent the lowest level interface between
the Atari's operating system and hardware, and are called via the
680X0 Trap #13. Preferably, these functions should not be used by
application programs, as substantially more powerful functions on a
higher level are available to provide better alternatives. Altogether
the following functions are available:
| Bconin |
Read a character from a device |
| Bconout |
Send a character to a peripheral unit |
| Bconstat |
Get input status of a peripheral unit |
| Bcostat |
Get status of a standard output device |
| Drvmap |
Get information about attached devices |
| Getbpb |
Get address to the bios parameter block of a unit |
| Getmpb |
Speicherparameterblock ermitteln. |
| Kbshift |
Fetch/set status of the shift keys |
| Mediach |
Ask if the media has been changed |
| Rwabs |
Direct read/write operation on a unit |
| Setexc |
Set an get interrupt vector |
| Tickcal |
Get time difference between two timer calls
|
The BIOS is reentrant in MagiC. This means that these functions
can be also called up repeatedly from interrupts (as long as the
relevant supervisor stack does not overflow...).
Note:
The of the BIOS is still present (for
reasons of compatibility), but it is not used by the system.
The stack checks of Turbo C/Pure-C will fail for routines that
are executed in supervisor-mode (under TOS this could happen until
now only for USERDEF routines in the AES, that are also executed
in supervisor-mode).
If you hook your own routines into the BIOS, then make sure
that you construct them to be fully reentrant. Make no assumptions
about the contents of the !
The BIOS receives its parameters from the stack; for this the
last argument from the parameter list is stored as the first on the
stack. Function results are returned in the processor register d0.
Only registers d3-d7 and a3-a7 are saved, all others may be altered by
the call.
See also: GEMDOS XBIOS Reset vector VT-52 terminal
3.1.1 bios-trap
| Name: |
»Bios« - Execute bios-trap |
| Syntax: |
LONG bios ( VOID, ... ); |
| Description: |
The routine bios executes a TRAP #13 exception. The parameters
passed depend on the particular BIOS function in each case. |
| Return value: |
The function returns a value of the data type LONG. |
| See also: |
gemdos xbios BIOS Dispatcher
|
3.1.2 Bconin
| Name: |
Bios console input |
| Opcode: |
2 |
| Syntax: |
int32_t Bconin ( int16_t dev ); |
| Description: |
The BIOS routine Bconin reads in a character from a
peripheral device. The following devices can be specified for
dev:
| dev |
Meaning |
| 0 |
prn: (Printer/Parallel port) |
| 1 |
aux: (aux device, the RS-232 port) |
| 2 |
con: (Console) |
| 3 |
MIDI port |
| 4 |
Keyboard port |
| 5 |
Screen |
| 6 |
ST compatible RS232 port (Modem 1) |
| 7 |
SCC channel B (Modem 2) |
| 8 |
TTMFP serial port (Modem 3) |
| 9 |
SCC channel A (Modem 4) |
Note that the device numbers from 6 up are only available from the
TOS030 of the Atari-TT. A wrong declaration for dev can lead
to a system crash. |
| Return value: |
The function returns the read-in character as an ASCII value
in the bits 0..7. When reading from the console, the bits 16 to 23
contain the scan-code of the relevant key. If, in addition, the
corresponding bit of the system variable conterm is set, then the bits
24 to 31 contain the current value of Kbshift. |
| Availability: |
All TOS versions. |
| See also: |
Binding Bconout Keytbl Bconmap
|
3.1.2.1 Bindings for Bconin
| C: |
int32_t Bconin ( int16_t dev ); |
| Assembler: |
move.w dev,-(sp) ; Offset 2
move.w #2,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #4,sp ; Correct stack
|
3.1.3 Bconout
| Name: |
Bios console output |
| Opcode: |
3 |
| Syntax: |
VOID Bconout ( int16_t dev, int16_t c ); |
| Description: |
The BIOS routine Bconout writes the character c to
the peripheral device dev. The following devices can be specified for
dev:
| dev |
Meaning |
| 0 |
prn: (Printer/Parallel port) |
| 1 |
aux: (Aux device, the RS-232 port) |
| 2 |
con: (Console, VT-52 terminal) |
| 3 |
MIDI port |
| 4 |
Keyboard port |
| 5 |
Screen |
| 6 |
ST compatible RS-232 port (Modem 1) |
| 7 |
SCC channel B (Modem 2) |
| 8 |
TTMFP serial port (Modem 3) |
| 9 |
SCC channel A (Modem 4) |
Note that the device numbers from 6 up are only available from the
TOS030 of the Atari-TT.
Note: The function only returns when the character has
actually been output by the relevant device. A wrong declaration for
dev can lead to a system crash. All codes from 0x00 to 0xFF
for the character c are interpreted as printable characters.
Output via (5) is, incidentally, faster than via (2), as the VT-52
sequences do not have to be evaluated. |
| Return value: |
The function does not return a result. |
| Availability: |
All TOS versions. |
| See also: |
Binding Bconin Bconstat Bconmap
|
3.1.3.1 Bindings for Bconout
| C: |
VOID Bconout ( int16_t dev, int16_t c ); |
| Assembler: |
move.w c,-(sp) ; Offset 4
move.w dev,-(sp) ; Offset 2
move.w #3,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #6,sp ; Correct stack
|
3.1.4 Bconstat
| Name: |
Bios console status |
| Opcode: |
1 |
| Syntax: |
int16_t Bconstat ( int16_t dev ); |
| Description: |
The BIOS routine Bconstat establishes the input status of a
standard peripheral device dev. The following devices can be specified
for dev:
| dev |
Meaning |
| 0 |
prn: (Printer/Parallel port) |
| 1 |
aux: (Aux device, the RS-232 port) |
| 2 |
con: (Console) |
| 3 |
MIDI port |
| 4 |
Keyboard port |
| 5 |
Screen |
| 6 |
ST compatible RS-232 port (Modem 1) |
| 7 |
SCC channel B (Modem 2) |
| 8 |
TTMFP serial port (Modem 3) |
| 9 |
SCC channel A (Modem 4) |
Note that the device numbers from 6 up are only available from the
TOS030 of the Atari-TT. A wrong declaration for dev can lead
to a system crash. |
| Return value: |
The function returns -1 when there are characters waiting in
the buffer, and 0 if this is not the case. |
| Availability: |
All TOS versions. |
| See also: |
Binding Bconin Bconout Bconmap
|
3.1.4.1 Bindings for Bconstat
| C: |
int16_t Bconstat ( int16_t dev ); |
| Assembler: |
move.w dev,-(sp) ; Offset 2
move.w #1,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #4,sp ; Correct stack
|
3.1.5 Bcostat
| Name: |
Bios output status |
| Opcode: |
8 |
| Syntax: |
int32_t Bcostat ( int16_t dev ); |
| Description: |
The BIOS routine Bcostat establishes the status of a
standard output device dev. The following devices can be specified for
dev on the Atari:
| dev |
Meaning |
| 0 |
prn: (Printer/Parallel port) |
| 1 |
aux: (Aux device, the RS-232 port) |
| 2 |
con: (Console) |
| 3 |
Keyboard port |
| 4 |
MIDI port |
| 5 |
Screen |
| 6 |
ST compatible RS-232 port (Modem 1) |
| 7 |
SCC channel B (Modem 2) |
| 8 |
TTMFP serial port (Modem 3) |
| 9 |
SCC channel A (Modem 4) |
Note that the device numbers from 6 up are only available from the
TOS030 of the Atari-TT.
Note: According to Atari, the swap between the MIDI port
(4) and the intelligent keyboard (3) compared to other BIOS
functions has been retained from a bug in TOS 1.0 for reasons of
compatibility. |
| Return value: |
The function returns the status of the output device, namely
-1 if characters could be written, and 0 if the buffer is full. |
| Availability: |
All TOS versions. |
| See also: |
Binding Bconout Bconmap
|
3.1.5.1 Bindings for Bcostat
| C: |
int32_t Bcostat ( int16_t dev ); |
| Assembler: |
move.w dev,-(sp) ; Offset 2
move.w #8,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #4,sp ; Correct stack
|
3.1.6 Drvmap
| Name: |
drive map |
| Opcode: |
10 |
| Syntax: |
int32_t Drvmap ( VOID ); |
| Description: |
The BIOS routine Drvmap establishes the mounted drives. For
each mounted drive one bit is set. Valid are:
| Bit 0: |
Drive A |
| Bit 1: |
Drive B etc. (max 32 devices possible)
|
Note: The function returns the contents of the system
variable _drvbits. To determine which drives are recognized by GEMDOS,
you have to use the function Dsetdrv. |
| Return value: |
The function returns a bit-vector for the connected (mounted)
drives. |
| Availability: |
All TOS versions. |
| See also: |
Binding Dsetdrv
|
3.1.6.1 Bindings for Drvmap
| C: |
int32_t Drvmap ( VOID ); |
| Assembler: |
move.w #$A,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #2,sp ; Correct stack
|
| GFA-Basic: |
Fehler%=Bios(10)
|
3.1.7 Getbpb
| Name: |
Get Bios parameter block |
| Opcode: |
7 |
| Syntax: |
BPB *Getbpb ( int16_t dev ); |
| Description: |
The BIOS routine Getbpb establishes the BIOS parameter
block of the device dev, which is coded as follows:
| dev |
Meaning |
| 0 |
Drive A |
| 1 |
Drive B |
| 2 |
Drive C |
Any further drives follow in a similar way. By calling this
function the media-change status in the BIOS is reset. |
| Return value: |
The function returns the address of the BIOS parameter
block. |
| Availability: |
All TOS versions. |
| See also: |
Binding Getmpb
|
3.1.7.1 Bindings for Getbpb
| C: |
BPB *Getbpb ( int16_t dev ); |
| Assembler: |
move.w dev,-(sp) ; Offset 2
move.w #7,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #4,sp ; Correct stack
|
| GFA-Basic: |
Fehler%=Bios(7,W:dev%)
|
3.1.8 Getmpb
| Name: |
Get memory parameter block |
| Opcode: |
0 |
| Syntax: |
VOID Getmpb ( MPB *ptr ); |
| Description: |
The BIOS routine Getmpb serves for initialising the memory
management and is called at bootup by GEMDOS to create the original
TPA. After this, Getmbp may not be used any more. |
| Return value: |
This function does not return a result. |
| Availability: |
All TOS versions. |
| See also: |
Binding Getbpb Program launch and TPA
|
3.1.8.1 Bindings for Getmpb
| C: |
VOID Getmpb ( MPB *ptr ); |
| Assembler: |
pea ptr ; Offset 2
move.w #0,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #6,sp ; Correct stack
|
3.1.9 Kbshift
| Name: |
Keyboard shift status of the 'special' keys. |
| Opcode: |
11 |
| Syntax: |
int32_t Kbshift ( int16_t mode ); |
| Description: |
The BIOS routine Kbshift establishes or alters the current
state of the keyboard 'special' keys. If mode is negative,
then only the state is established. If mode is 0 or greater
than 0, then the corresponding status will be set.
The individual bits are defined as follows:
| Bit |
Meaning |
| 0 |
Right shift key |
| 1 |
Left shift key |
| 2 |
Control key |
| 3 |
ALT key |
| 4 |
Caps-lock |
| 5 |
Right mouse button |
| 6 |
Left mouse button |
| 7 |
Alt Gr since TOS 4.06 (Milan) |
Note: The function simply inquires an internal system
variable of the BIOS, whose address can be calculated via _sysbase
if required.
For TOS 1.0 this system variable is at address 0xE1B. |
| Return value: |
The function returns the set keyboard status. |
| Availability: |
All TOS versions. |
| See also: |
Binding
|
3.1.10 Bindings for Kbshift
| C: |
int32_t Kbshift ( int16_t mode ); |
| Assembler: |
move.w mode,-(sp) ; Offset 2
move.w #$B,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #4,sp ; Correct stack
|
3.1.11 Mediach
| Name: |
Media change |
| Opcode: |
9 |
| Syntax: |
int32_t Mediach ( int16_t dev ); |
| Description: |
The BIOS routine Mediach establishes whether the
data-carrier 'medium' on the device dev has been changed since
the last disk operation of the particular drive. Valid are:
| dev |
= 0 |
(Drive A) |
| |
= 1 |
(Drive B) |
| |
= 2 |
(Drive C, similarly for other drives) |
Note: One should never assume that a device's medium
cannot be exchanged (removable disk catridge, CD-ROM, floppy drive,
floptical ...). The recognition of a floppy disk change usually only
works reliably if the floppy is not write-protected. In addition one
should note that during formatting a floppy different serial numbers
will be asssigned. |
| Return value: |
The function returns an integer-value with the following
meaning:
| Value |
Meaning |
| 0 |
Media definitely has not changed. |
| 1 |
Media might have changed. |
| 2 |
Media definitely has changed. |
|
| Availability: |
All TOS versions. |
| See also: |
Binding Flopfmt Protobt
|
3.1.11.1 Bindings for Mediach
| C: |
int32_t Mediach ( int16_t dev ); |
| Assembler: |
move.w dev,-(sp) ; Offset 2
move.w #9,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #4,sp ; Correct stack
|
| GFA-Basic: |
Fehler%=Bios(9,W:dev%)
|
3.1.12 Rwabs
| Name: |
Read/write absolute |
| Opcode: |
4 |
| Syntax: |
int32_t Rwabs ( int16_t rwflag, VOID *buff, int16_t cnt,
int16_t recnr, int16_t dev, int32_t lrecno ); |
| Description: |
The BIOS routine Rwabs reads or writes data directly resp.
from or to the drive that was specified with dev. The
parameter rwflag is a bit-vector that specifies the type of
operation. Valid are:
| rwflag-bit |
Meaning |
| 0 |
0 = Read
1 = Write |
| 1 |
0 = Pay regard to media change
1 = Do not read of affect media-change status |
| 2 |
0 = In case of error, start a retry
1 = Do not start a retry
For this, a hard disk driver that is compatible with AHDI 3.0 is
required. |
| 3 |
0 = Normal mode
1 = Physical mode (1)
For this, a hard disk driver that is compatible with AHDI 3.0 is
required.
|
cnt characters from buffer buff will be
transferred In recnr the starting sector on the drive will be
specified. lrecno will be used only if recnr has the
value -1, and an AHDI 3.0-compatible hard disk driver is available. |
| Return value: |
The function returns 0 if the access was successful, otherwise
a negative number. |
| Availability: |
All TOS versions. |
| See also: |
Binding
|
3.1.12.1 Bindings for Rwabs
| C: |
int32_t Rwabs ( int16_t rwflag, VOID *buff, int16_t cnt,
int16_t recnr, int16_t dev, int32_t lrecno ); |
| Assembler: |
move.l lrecno,-(sp) ; Offset 14
move.w dev,-(sp) ; Offset 12
move.w recnr,-(sp) ; Offset 10
move.w cnt,-(sp) ; Offset 8
pea buff ; Offset 4
move.w rwflag,-(sp) ; Offset 2
move.w #4,-(sp) ; Offset 0
trap #13 ; Call BIOS
lea $12(sp),sp ; Correct stack
|
| GFA-Basic: |
Fehler%=Bios(4,W:rwflag%,L:buff%,W:cnt%,W:recnr%,W:dev%,L:lrecno%)
|
3.1.13 Setexc
| Name: |
Set exception vector |
| Opcode: |
5 |
| Syntax: |
int32_t Setexc ( int16_t number, VOID (*vec)() ); |
| Description: |
The BIOS routine Setexc sets or reads the contents of
exception vectors. Valid are:
| Parameter |
Meaning |
| number |
Number of the vector |
| vec |
New address (or -1) |
Note: Ifvec is -1L, then the vector's previous
value is returned.
The number of the exception vector to be set is, by the way,
identical to the address to be set divided by 4. |
| Return value: |
The function returns the previous (or current) value of the
vector. |
| Availability: |
All TOS versions. |
| See also: |
Binding System Vectors System variables
|
3.1.13.1 Bindings for Setexc
| C: |
int32_t Setexc ( int16_t number, VOID (*vec)() ); |
| Assembler: |
pea exchdlr ; Offset 4
move.w number,-(sp) ; Offset 2
move.w #5,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #8,sp ; Correct stack
|
3.1.14 Tickcal
| Name: |
Tick calculation |
| Opcode: |
6 |
| Syntax: |
int32_t Tickcal ( void ); |
| Description: |
The BIOS routine Tickcal returns the number of milliseconds
that have elapsed between two calls of the system timer.
Note: For this the function accesses the _timr_ms system
variable. |
| Return value: |
Number of corresonding milliseconds |
| Availability: |
All TOS versions. |
| See also: |
Binding System variables
|
3.1.14.1 Bindings for Tickcal
| C: |
LONG Tickcal ( VOID ); |
| Assembler: |
move.w #6,-(sp) ; Offset 0
trap #13 ; Call BIOS
addq.l #2,sp ; Correct stack
|