TCALL (SPC700): Difference between revisions

Latest revision as of 11:40, 20 September 2024


Basic Info
Addressing Mode	Opcode	Length	Speed	Vector Address
Implied (type 3)	01	1 byte	8 cycles	$FFDE
Implied (type 3)	11	1 byte	8 cycles	$FFDC
Implied (type 3)	21	1 byte	8 cycles	$FFDA
Implied (type 3)	31	1 byte	8 cycles	$FFD8
Implied (type 3)	41	1 byte	8 cycles	$FFD6
Implied (type 3)	51	1 byte	8 cycles	$FFD4
Implied (type 3)	61	1 byte	8 cycles	$FFD2
Implied (type 3)	71	1 byte	8 cycles	$FFD0
Implied (type 3)	81	1 byte	8 cycles	$FFCE
Implied (type 3)	91	1 byte	8 cycles	$FFCC
Implied (type 3)	A1	1 byte	8 cycles	$FFCA
Implied (type 3)	B1	1 byte	8 cycles	$FFC8
Implied (type 3)	C1	1 byte	8 cycles	$FFC6
Implied (type 3)	D1	1 byte	8 cycles	$FFC4
Implied (type 3)	E1	1 byte	8 cycles	$FFC2
Implied (type 3)	F1	1 byte	8 cycles	$FFC0


Flags Affected
N	V	P	B	H	I	Z	C
.	.	.	.	.	.	.	.

TCALL (Table CALl) is an SPC700 instruction that calls a subroutine whose 16-bit address is stored in the uppermost page. The low byte of the address of the vector (pointer to subroutine) is a function of the high nybble of the opcode, equal to $DE - n*2. The high byte of the vector address is always $FF.

No flags are affected.

Syntax

TCALL n

where n is the vector call number, a decimal integer from 0 to 15, which becomes the high nybble of the opcode.

External Links

Official Nintendo documentation on TCALL: Table C-16 Appendix C-9
anomie's SPC700 doc
https://forums.nesdev.org/viewtopic.php?t=13313

@@ Line 1: / Line 1: @@
-{| class="wikitable" style="float:right;clear:right;width:40%"
+{| class="wikitable" style="float:right;clear:right;width:50%"
 !colspan="8"|Basic Info
 |+
@@ Line 6: / Line 6: @@
 |'''Length'''
 |'''Speed'''
+|'''Vector Address'''
 |+
-|implied
+|[[Implied]] (type 3)
 |01
 |1 byte
 |8 cycles
+|$FFDE
 |+
-|implied
+|[[Implied]] (type 3)
 |11
 |1 byte
 |8 cycles
+|$FFDC
 |+
-|implied
+|[[Implied]] (type 3)
 |21
 |1 byte
 |8 cycles
+|$FFDA
 |+
-|implied
+|[[Implied]] (type 3)
 |31
 |1 byte
 |8 cycles
+|$FFD8
 |+
-|implied
+|[[Implied]] (type 3)
 |41
 |1 byte
 |8 cycles
+|$FFD6
 |+
-|implied
+|[[Implied]] (type 3)
 |51
 |1 byte
 |8 cycles
+|$FFD4
 |+
-|implied
+|[[Implied]] (type 3)
 |61
 |1 byte
 |8 cycles
+|$FFD2
 |+
-|implied
+|[[Implied]] (type 3)
 |71
 |1 byte
 |8 cycles
+|$FFD0
 |+
-|implied
+|[[Implied]] (type 3)
 |81
 |1 byte
 |8 cycles
+|$FFCE
 |+
-|implied
+|[[Implied]] (type 3)
 |91
 |1 byte
 |8 cycles
+|$FFCC
 |+
-|implied
+|[[Implied]] (type 3)
 |A1
 |1 byte
 |8 cycles
+|$FFCA
 |+
-|implied
+|[[Implied]] (type 3)
 |B1
 |1 byte
 |8 cycles
+|$FFC8
 |+
-|implied
+|[[Implied]] (type 3)
 |C1
 |1 byte
 |8 cycles
+|$FFC6
 |+
-|implied
+|[[Implied]] (type 3)
 |D1
 |1 byte
 |8 cycles
+|$FFC4
 |+
-|implied
+|[[Implied]] (type 3)
 |E1
 |1 byte
 |8 cycles
+|$FFC2
 |+
-|implied
+|[[Implied]] (type 3)
 |F1
 |1 byte
 |8 cycles
+|$FFC0
 |}
@@ Line 91: / Line 108: @@
 !colspan="8"|Flags Affected
 |+
-|N
+|[[Negative Flag|N]]
-|V
+|[[Overflow Flag|V]]
-|P
+|[[Direct Page Flag|P]]
-|B
+|[[Break Flag|B]]
-|H
+|[[Half-Carry Flag|H]]
-|I
+|[[Interrupt Enable Flag|I]]
-|Z
+|[[Zero Flag|Z]]
-|C
+|[[Carry Flag|C]]
 |+
 |.
@@ Line 110: / Line 127: @@
 |}
-'''TCALL''' (Table CALl) is an [[SPC700]] instruction that calls a subroutine in the [[uppermost page]].  The low byte of the effective address which is called is a function of the high nibble of the opcode.  The high byte of the effective address is always $FF.
+'''TCALL''' (Table CALl) is an [[SPC700]] instruction that calls a subroutine whose 16-bit address is stored in the [[uppermost page]].  The low byte of the address of the vector (pointer to subroutine) is a function of the high nybble of the opcode, equal to $DE - n*2.  The high byte of the vector address is always $FF.
+No flags are affected.
+=== Syntax ===
+<pre>
+TCALL n
+</pre>
+where n is the '''vector call number''', a decimal integer from 0 to 15, which becomes the high nybble of the opcode.
 === See Also ===
 * [[CALL]]
 * [[PCALL]]
+* [[RET]]
+* [[SPC700/IPL ROM]]
 === External Links ===
-* Official Nintendo documentation on TCALL: [https://archive.org/details/SNESDevManual/book1/page/n234 Appendix C-9]
+* Official Nintendo documentation on TCALL: Table C-16 [https://archive.org/details/SNESDevManual/book1/page/n234 Appendix C-9]
-* [https://www.romhacking.net/documents/197| anomie's SPC700 doc]
+* [https://www.romhacking.net/documents/197 anomie's SPC700 doc]
+* https://forums.nesdev.org/viewtopic.php?t=13313
 [[Category:ASM]]
 [[Category:SPC700]]
 [[Category:Subroutine Call Return Commands]]
+[[Category:One-byte Instructions]]