< 5/19>SMPC User's Manual/2.3 Reset system management commands

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SMPC User's Manual/Chapter 2 SMPC Commands

■2.3 Reset system management commands

Details of reset system management commands are shown in table format. The table of each command and notes are as follows. In addition, by using status flags in all commands, you can manage double issuing of commands.

●SMPC interrupt

Items marked as "occurrence" generate an SMPC interrupt to the SH-2 via the SCU at the end of the command. Additionally, interrupts can be enabled/disabled by setting the SCU.

●IREG, OREG

Details of IREG and OREG used in the command are shown.
Command parameters are parameters that are set in IREG before issuing the command.
Result parameters are parameters set in OREG by command execution.
Result parameter OREG31 is set by SMPC when command processing begins. The command code is output to OREG31.

By using it together with status flag (SF),

Which command is being executed ( SF=1 )
Which command finished ( SF=0 )

can be judged.

●Execution time

The execution time is calculated from the number of steps in the SMPC internal firmware. If there is a conflict with an internal task such as RTC increment, the command execution time will change, so it is described in the range of minimum and maximum values.

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No.1

MSHON

Master SH-2 ON

Command code 00H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

Turn on master SH-2.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	0	0	0	0

remarks

User use is prohibited.

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No.2

SSHON

Slave SH-2 ON

Command code 02H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

Turn on slave SH-2.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	0	0	1	0

remarks

none

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No.3

SSHOFF

Slave SH-2 OFF

Command code 03H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

Turn off slave SH-2.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	0	0	1	1

remarks

Issuance of this command is prohibited under the following conditions.

When slave SH-2 is accessing external bus (A-Bus, B-Bus, CPU-Bus).

In other words, it cannot be used unless the slave SH-2 is accessing the cache inside the CPU.

If the above management is difficult on the application side, please use the system library's clock change ( SYS_CHGSYSCK ).

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No.4

SNDON

sound on

Command code 06H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

Turn on the sound CPU (MC68EC000).

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	0	1	1	0

remarks

See " Sound OFF " command.

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No.5

SNDOFF

Sound OFF

Command code 07H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

Turn off the sound CPU (MC68EC000).

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	0	1	1	1

remarks

When stopping the sound CPU, be sure to strictly observe the following restrictions.

＜＜ Limitations on stopping and starting sound blocks＞＞

When the sound block is stopped, there must not be a non-access period of 0.5 seconds or more from the main system (SH2 side) to the sound RAM.
If you want to stop Sound Block, please stop it only for the minimum necessary period such as loading the sound driver, and then restart it immediately.
If you do not need to use the sound CPU (MC68EC000), you need to take measures such as running a dummy program (just an infinite loop).
If these restrictions are not observed, the operation of the sound RAM and sound block cannot be guaranteed.

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No.6

CDON

CD ON

Command code 08H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=40μsec

Functional details

Turn on the CD.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	1	0	0	0

remarks

User use is prohibited.

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No.7

CDOFF

CD OFF

Command code 09H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=40μsec

Functional details

Turn off the CD.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	1	0	0	1

remarks

By executing this command, the contents of the CD buffer (DRAM) will not be retained.

User use is prohibited.

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No.8

SYSRES

Whole system reset

Command code 0DH SMPC interrupt cannot be generated IREG unused OREG 31 Execution time 100msec+α

Functional details

Reset the entire Sega Saturn system.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	1	1	0	1

remarks

By executing this command, all functions are reset (initialized), the master SH-2 operates from the power ON vector, and the boot ROM is started. All memory contents are not retained except for the 256K-bit battery-backed RAM.

User use is prohibited.

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No.9

CKCHG352

Clock change 352 mode

Command code 0EH SMPC interrupt cannot be generated IREG unused OREG 31 Execution time 100msec+α

Functional details

Switch the Sega Saturn's system clock from 320 mode to 352 mode.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	1	1	1	0

remarks

Issuance of this command from applications is prohibited. Call the clock change routine in the Sega Saturn boot ROM.

When a clock change is executed, each LSI becomes as follows.

VDP1, VDP2, SCU, SCSP: Default value at power ON

Master SH-2: Return from boot ROM clock change routine

Slave SH-2: OFF

CD block: hold

Work RAM: Retention

VRAM: Not retained

User use is prohibited.
If you use it, please use the system library clock change ( SYS_CHGSYSCK ).

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No.10

CKCHG320

Clock change 320 mode

Command code 0FH SMPC interrupt cannot be generated IREG unused OREG 31 Execution time 100msec+α

Functional details

Switch the Sega Saturn's system clock from 352 mode to 320 mode.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	0	1	1	1	1

remarks

Issuance of this command from applications is prohibited. Call the clock change routine in the Sega Saturn boot ROM.

When a clock change is executed, each LSI becomes as follows.

VDP1, VDP2, SCU, SCSP: Default value at power ON

Master SH-2: Return from boot ROM clock change routine

Slave SH-2: OFF

CD block: hold

Work RAM: Retention

VRAM: Not retained

User use is prohibited.
If you use it, please use the system library clock change ( SYS_CHGSYSCK ).

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No.11

NMIREQ

NMI request

Command code 18H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

Request NMI from master SH-2.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	1	1	0	0	0

remarks

Requests NMI unconditionally even if disabled by the RESDISA command .

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No.12

RESENAB

reset enable

Command code 19H SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

On Sega Saturn, an NMI is generated when the reset button on the main body panel is pressed. This command enables NMI generation.
The default value when booting with BOOR ROM is enable.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	1	1	0	0	1

remarks

To prevent chattering, an NMI is generated when the reset button is pressed for 3VINT (3/60sec).

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No.13

RESDISA

reset disable

Command code 1AH SMPC interrupt cannot be generated IREG unused OREG 31 Execution time max=xxx 　　　　　　　　min=30μsec

Functional details

On the Sega Saturn, an NMI is generated when the reset button on the main body panel is pressed. This command disables NMI generation.
The default value when booting with BOOR ROM is enable.

command parameters

none

Result parameters

OREG31	bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
2010005FH	0	0	0	1	1	0	1	0

remarks

The state of the reset switch is only indicated by the RESB bit (bit4) of the SR (status register), and no NMI output is performed to the master SH-2. The RESB bit indicates the state of the button at V-BLANK-IN.

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