Values for SYS command and use/call in ML code
Posted: Fri Oct 02, 2020 8:09 am
Hi!
I was searching commented ROM/RAM disassemply/map for:
- value for A, X, Y register for SYS command - success - found
- value SP for SYS command - success - found
- SYS routine address - success found
- LO and HI byte for use with SYS command as address - never found
Like we know SYS command can be performed with preloaded register values and even preform in ML code using LO and HI byte.
So, Q is: Where are in RAM located LO and HI bytes for address on VIC20 computer?
For complete found info:
C128
-----
0005 SR value for SYS
0006 A reg. value for SYS
0007 X reg. value for SYS
0008 Y reg. value for SYS
0009 SP value for SYS
0002 Bank value for SYS
0003 LO-byte SYS address
0004 HI-byte SYS address
22661 / $5885 SYS
C64
----
780 $030C A value for SYS
781 $030D X value for SYS
782 $030E Y value for SYS
783 $030F SP value for SYS
20 $0014 LO-byte SYS address
21 $0015 HI-byte SYS address
57642 $E12A SYS
VIC20
-----
780 $030C A value for SYS
781 $030D X value for SYS
782 $030E Y value for SYS
783 $030F SR value for SYS
57639 $E127 SYS
C16+4
-----
2034 $07F2 A value for SYS
2035 $07F3 X value for SYS
2036 $07F4 Y value for SYS
2037 $07F5 SR value for SYS
Thank you for help.
Miro
I was searching commented ROM/RAM disassemply/map for:
- value for A, X, Y register for SYS command - success - found
- value SP for SYS command - success - found
- SYS routine address - success found
- LO and HI byte for use with SYS command as address - never found
Like we know SYS command can be performed with preloaded register values and even preform in ML code using LO and HI byte.
So, Q is: Where are in RAM located LO and HI bytes for address on VIC20 computer?
For complete found info:
C128
-----
0005 SR value for SYS
0006 A reg. value for SYS
0007 X reg. value for SYS
0008 Y reg. value for SYS
0009 SP value for SYS
0002 Bank value for SYS
0003 LO-byte SYS address
0004 HI-byte SYS address
22661 / $5885 SYS
C64
----
780 $030C A value for SYS
781 $030D X value for SYS
782 $030E Y value for SYS
783 $030F SP value for SYS
20 $0014 LO-byte SYS address
21 $0015 HI-byte SYS address
57642 $E12A SYS
VIC20
-----
780 $030C A value for SYS
781 $030D X value for SYS
782 $030E Y value for SYS
783 $030F SR value for SYS
57639 $E127 SYS
C16+4
-----
2034 $07F2 A value for SYS
2035 $07F3 X value for SYS
2036 $07F4 Y value for SYS
2037 $07F5 SR value for SYS
Thank you for help.
Miro