Exception Vector Processing

ABOUT

The 68000 processor used by the TI-89 keeps a #1024 byte vector table beginning at $000000. This table contains pointers to routines used by the cpu, operating system, and the user. The vectors are refered to with an index from #0 through #255. This document describes some of these vectors as they relate to the AMS.

Exception Vector Assignment Table
Address	Vector Function	Vector # (Decimal)	Vector # (Hexadecimal)
$000	Reset Vector - Contains initial SSP & PC	0	$0
$008	Bus Error	2	$2
$00C	Address Error	3	$3
$010	Illegal Instruction	4	$4
$014	Zero Divide	5	$5
$018	CHK Instruction	6	$6
$01C	TRAPV Instruction	7	$7
$020	Privilege Violation	8	$8
$024	Trace	9	$9
$028	Line 1010 Emulator	10	$A
$02C	Line 1111 Emulator	11	$B
$030	Unassigned: Reserved by Motorola	12-14	$C-$E
$03C	Uninitialized Interrupt Vector	15	$F
$040	Unassigned: Reserved by Motorola	16-23	$10-$17
$060	Spurious Interrupt	24	$18
$064	Level 1 Interrupt Autovector	25	$19
$068	Level 2 Interrupt Autovector	26	$1A
$06C	Level 3 Interrupt Autovector	27	$1B
$070	Level 4 Interrupt Autovector	28	$1C
$074	Level 5 Interrupt Autovector	29	$1D
$078	Level 6 Interrupt Autovector	30	$1E
$07C	Level 7 Interrupt Autovector	31	$1F
$080	TRAP $0 (#0)	32	$20
$084	TRAP $1 (#1)	33	$21
$088	TRAP $2 (#2)	34	$22
$08C	TRAP $3 (#3)	35	$23
$090	TRAP $4 (#4)	36	$24
$094	TRAP $5 (#5)	37	$25
$098	TRAP $6 (#6)	38	$26
$09C	TRAP $7 (#7)	39	$27
$0A0	TRAP $8 (#8)	40	$28
$0A4	TRAP $9 (#9)	41	$29
$0A8	TRAP $A (#10)	42	$2A
$0AC	TRAP $B (#11)	43	$2B
$0B0	TRAP $C (#12)	44	$2C
$0B4	TRAP $D (#13)	45	$2D
$0B8	TRAP $E (#14)	46	$2E
$0BC	TRAP $F (#15)	47	$2F
$0C0	Unassigned: Reserved by Motorola	48-49	$30-$31
$0C8	AMS Jump Table Pointer	50	$32
$0CC	Unassigned: Reserved by Motorola	51-63	$33-$3F
$100	User Interrupt Vectors	64-25	$40-$FF
$400	End of Exception Vector Table

VECTOR ASSIGNMENTS ON THE TI-89

Line 1010 ($A) Emulator

Triggered when an op code beginning with 1010 is encountered; the operating system uses this to throw errors. The general format is $Axxx where xxx is the error code. The error codes are the same as printed in the calculators manual. Some error codes are not documented.

Line 1111 ($F) Emulator

Triggered when an op code beginning with 1111 is encountered.

AMS < 2.04 Print Line 1111 Emulator and Freeze.

AMS =>2.04 Call routine in jump table format is $F800 + JumpTableIndex.
Example: ClrScr is $19E in the jump table. $F800 + $19E = $F99E. So dc.w $F99E (or .word 0xF99E 'as' style) would call ClrScr. When using this method, the call takes 2 bytes compared to 6 bytes and is much slower than the traditional methods.

Auto Interrupts 1-7

The interrupt level can be set with OSSetSR or Trap #1. Setting an interrupt mask above $500 will disable the calculator's ability to save state information if there is a power outage.
There are 8 levels of interrupts available on the TI-89:

Interrupt Mask Settings
Interrupt Mask	Short Description	Disabled Interrupts
$700	Disable All Interrupts	Auto Interrupts 1, 2, 3, 4, 5, 6
$600	Disable ON key & Below	Auto Interrupts 1, 2, 3, 4, 5, 6
$500	Disable Timers & Below	Auto Interrupts 1, 2, 3, 4, 5
$400	Disable Link & Below	Auto Interrupts 1, 2, 3, 4
$300	Disable Slow Clock & Below	Auto Interrupts 1, 2, 3
$200	Disable Keyboard & Below	Auto Interrupts 1, 2
$100	Disable Key Scan	Auto Interrupts 1
$000	Enable All Interrupts	<NONE>

Auto Interrupt Descriptions
Interrupt Number	Description With Respect to the AMS
Auto Interrupt 1	Status Line: By default, it triggers about 395 times per second. Draws the status line.
Auto Interrupt 2	Keypress: Triggered when a key is pressed. A single keypress can generate multiple interrupts!
Auto Interrupt 3	Slow Clock: Not used by the AMS. Triggers exactly one time per second on HW2 calcs. On HW1 calcs, it triggers ~0.616322 times per second.
Auto Interrupt 4	Link:Triggered by the linking hardware for varoius reasons.
Auto Interrupt 5	Timers: Controls the 6 timers used by the TIOS (1-6 inclusive). This interrupt is triggered at 20 times per second if the programmable rate generator has not been altered. TIGCC hooks this interrupt to provide vector timers.
Auto Interrupt 6	ON KEY: Triggers when the ON KEY is pressed. A single keypress can generate multiple interrupts! It also seems to be triggered when battery power is low. That explains why doorsos breaks out of programs sometimes when STO is pressed.
Auto Interrupt 7	Protected Memory Violation: Triggers when a write is attempted at any address below $120 or any address from $E00000 - $FFFFFF. This is to prevent damage to the Exception Vector Table from a stack overflow for example. The user stack begins at $4BFF and grows backwards to $400, so most of the user vectors will be damaged before this interrupt triggers. To avoid this interrupt, you can add $40000 to the address that you want to write to. A second method is to clear bit #2 at $600001 to disable the interrupt; setting the bit enables the interrupt once again. Notes: The following instructions may be of interest in this interrupt... ... MOVE USP,A0 ;the address to the user stack is in a0 CMPA.L #$400,A0 ;compare with $400 BHI... ;if higher, then 'Protected Memory Error' is thrown... ;else 'Memory Error' is Thrown Auto Interrupt 7 cannot be disabled via the SR because it is not maskable. Instead, use port .........where did alh's page go =P

---to do--- clean this up... get rid of ugly table....

Trap Exception Table

Trap

Description

Input

Output

Notes

Trap #0 ($0)

Execute various supervisor mode functions.

D0 = function code

Known Functions:
0	sets the power state, switches flash to low power mode
1	Idle
2	Clear Break
3	Check Break
4	Reset
5
6	Error Lockup

Trap #1 ($1)

Interrupt Mask

D0.w = new interrupt mask

D0.l = old SR

OSSetSR uses this trap.

Trap #2 ($2)

Reset

none

The calculator is reset. On ams 2.xx, the archive will be intact.

Used by Trap #8, so redirect this trap to avoid a reset if you use it.

Trap #3 ($3)

OSenqueue

parameters on stack C style:
(short data, void* Queue)

D0.w = 1 on success 0 on failure
Assume that D1-D2/A0-A1 are destroyed

This will not work if you want to use OSenqueue becuase OSenqueue expects to be run in user mode. It peforms rts instead of rte at the end of the routine.

Trap #4 ($4)

Turns the calculator off

Calculator is off... waits for the ON key to be pressed or a link interrupt to turn back on.

Trap #5 ($5

Prints Trap 5 with black bar and hangs

Trap #6 ($6)

Prints Trap 6 with black bar and hangs

Trap #7 ($7)

Prints Trap 7 with black bar and hangs

Trap #8 ($8)

Runs a block in supervisor mode.

LE_WORD Size;BYTE Code[];

The code is called (passed a5 with the end address), trap #2 is then called (put on the stack as the return address)

Trap #9 ($9)

Returns pointers to various system functions and tables

D0.w = function id

A0.l = pointer

Input Table
D0.w	Pointer
0	OSContrastUp
1	WinOpen
2	OSLinkReset
3	TIMERV *OSTimerVectors;
4	BYTE *OSContrast; (end of LCD_MEM)
5	WinStr
6	KEY_QUEUE *KeyBuffer;
7	OSqclear
8	CHARTYPE* CharTbl;
9	OSContrastUp
10	OSContrastDn
11	OSClearBreak
12	KEYCODE* KeyCodes;
13	OSCheckBreak
14	LCD_MEM
15	OSdequeue
16	RAMTest
17	WinMoveTo

Trap #10 ($A)

Self Test

Trap #11 ($B)

Handles all of the FLASH operations for the operating system. This trap needs to execute from the ram if writing is to be peformed.

D3 = function number
D4 = size
A2 = addr1
A3 = addr2

D3	Function
0	write
1	erase
2	addcert
3	getcert
4	cgetvernum

If (flen) function is copied and executed in RAM.

Trap #12 ($C)

Enter Supervisor Mode

none

d0.w contains previous SR upon return.

RTE won't work to restore user mode because this trap pop's the sr off of the stack and then peforms rts which pops the return address off of the stack

Trap #13 ($D)

Prints Trap 13 with black bar and hangs

Trap #14 ($E)

Prints Trap 14 with black bar and hangs

Trap #15 ($F)

Prints ER_throw with black bar and hangs.

External Links

Detached Solutions
Techno-Plaza ASM Lessons
TIGCC Cross Compiler
www.ticalc.org
www.calc.org