NFG Games + GameSX

This is an old revision of the document!

---

・TRAP exception handling list

・trap #10 Reset/power off handling

Arg	d0.l =	$58363801('X68'<<8+1)	Power off by front switch
		$58363802('X68'<<8+2)	Power off by external switch
		$58363803('X68'<<8+3)	Power off with soft switch
	
Software reset other than above

It is called from the power off interrupt and keyboard
processing or from the user program and performs power
off and reset processing by software.

It is hooked at Human68k startup. It will not be executed
immediately even if it is called during DOS call execution.
It will be called after it ends.

・trap #11 BREAK key processing

Arg	d0.b	Shift key status

Called from the keyboard process when the BREAK key is pressed
but ignored while executing disk related IOCS of $40 to $4F.
It is hooked at Human68k startup, it will not be executed
immediately even if it is called during DOS call execution.
It will be called after it ends.

If you press the BREAK key without pressing SHIFT, trap #13
is also executed after trap #11.

Since multiple calls are noe made, there is no need to have
a reentrant structure.

・trap #12 COPY key handling

Arg d0.b Shift key status

When the COPY key is pressed it is called from the keyboard
process and performs the hard copy process of the screen.

Since multiple calls are not made there is no need to have
a reentrant structure.

The following operations are performed depending on the
shift key state.

COPY		Reduced copy (1 color)
SHIFT + COPY	Enlarged copy (1 color)
CTRL  + COPY	Enlarged copy (4 colors)
OPT.1 + COPY	FF output.
OPT.2 + COPY	LF 〃

・trap #13 CTRL+C handling

Called from keyboard processing when CTRL+C and BREAK keys
are entered.

Usually routines that do not do anything are registered,
so they can be used by users.

trap #14 Error handling

Arg d7.w Error number

a5.l	String address (only for d7.w = $??00)

When ROM is started it just restarts waiting for key
input, but when Human68k starts up it is hooked and
replaced with a routine that displays a white strip
and waits for the users response.

If the system detects an error, set error number d7.w
and trap #14. In this error handling routine, depending
on the type of error, after outputting a message
according to the type of error, it waits for input from the
keyboard and sets d7.w to 1 (reexecution) or 2 (ignore) and
return. If abort is specified (will not return).

Error number

$00xx CPU Exception processing/unregistered interrupt (stop only)

		The lower byte is the vector number.
$0002	Bus error
$0003	Address error
$0004	Invalid instruction
$0005	Divide by 0
$0006	CHK instruction executed
$0007	TRAPV instruction executed
$0008	Privileged instruction executed
$001f	Interrupt(NMI) switch pressed

$01xx Unregistered IOCS call

	The lower byte is the IOCS call number.
	It is also called when using a call to SASI that can only be
	performed on FD or vice versa.

Error number

$00xx CPU Exception processing/unregistered interrupt (stop only)

		The lower byte is the vector number.
$0002	Bus error
$0003	Address error
$0004	Invalid instruction
$0005	Divide by 0
$0006	CHK instruction executed
$0007	TRAPV instruction executed
$0008	Privileged instruction executed
$001f	Interrupt(NMI) switch pressed

$01xx Unregistered IOCS call

	The lower byte is the IOCS call number.
	It is also called when using a call to SASI that can only be
	performed on FD or vice versa.

$02xx～$0fxx Reserved $10xx～$1fxx Error (cancellation only) $20xx～$2fxx Error (retry only) $30xx～$3fxx Error (re-execute & cancel)

$301f	Interrupt(NMI) switch pressed

$40xx～$4fxx Error (ignore only) $50xx～$5fxx Error (ignore & cancel) $60xx～$6fxx Error (ignore & rerun) $70xx～$7fxx Error (ignore & re-execute & cancel) $80xx～$efxx Reserved $f0xx～$fdxx Interrupt other than F series DOS call (only stop) $fexx Floating-point operation package not installed (abort only) $ffxx Unregistered DOS call

	In Human68k version 3.0x unregistered DOS call returns -1 and
	error handling is not called.
	
	When the interrupt switch is pressed the error numbers are two
	numbers, $001F and $003F. Usually the latter is used.
	
	For error numbers from $1000~$7FFF, bits 4, 5, and 6 of the
	high-order byte are cancelled. It corresponts to retry, ignore.
	The contents of the lower byte at this time are as follows.

$00 User defined (put a string address in a5.l) $01 An invalid unit number was specified. $02 Disk is not inserted. $03 Invalid command specified in the device driver. $04 CRC error. $05 Disk management area is destroyed. $06 Seek error. $07 Invalid media. $08 Sector not found. $09 Printer is not connected. $0a Write error. $0b Read error. $0c Other error. $0d Write protected (remove protect and put the same disk). $0e Impossible to write. $0f File sharing violation.

If the low-order byte is 0 the user can specify the character
string to be displayed. The address of the character string is
passed in a5.l and the character string must not be more than
the display witdh 52 digits. However, as the error code of the
device driver, if the low byte (3rd byte from the head of the
request header) is 0, it is handled as normal ternimation and it
is impossible to pass the address of the character string, so this
function can not be used.

・trap #15 IOCS processing

Arg d0.b IOCS call number

Execute IOCS. During execution, the IOCS call number is stored
in one word from IOCS work area $A0E (upper byte is always 0).
Arguments and return values other than d0.b differ depending
on the call number.

To speed up the IOCS call, execute the shortcut call by the 
following method while in supervisor mode.

movea.l	(IOCS call number*4+$400),a0
jsr	(a0)

Each function of IOCS is created as a subroutine returning with
rts. There is no problem in destroying a0.l (from the point of
view of the user, there is no guarantee that it will be saved
when shortcutting), do not destroy registers that do not pass
other return values.

How handles vector base register 'vbr'

In X68030 (ROM IOCS version 1.3), vbr can be enabled. After
checking that the following vectors are standard vectors
pointing inside the ROM, change the value obtained by
subtracting 2 from each address. However, in some IOCS calls,
routines in ROM can not deal with what is calling(?).

trap #15(IOCS processing address table is also changed to vbr+$400)
IOCS _FNTGET
IOCS _OPMINTST
IOCS _TIMERDST
IOCS _VDISPST
IOCS _CRTCRAS
IOCS _HSYNCST
IOCS _PRNINTST
IOCS _B_INTVCS