◆ Details of result parameters

● Peripheral control status

SMPC outputs the peripheral control status to the status register (SR) when using SMPC control mode. The status register (SR) is a register that can be read independently of the INTBACK command. However, even if this register is read while the INTBACK command is not in use, it is undefined except for the RESB bit.

Figure 3.13 Peripheral control status

bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
1	PDL	NPE	RESB	P2MD1	P2MD0	P1MD1	P1MD0

P1MD: Port 1 mode

00:15 byte mode (returns peripheral data up to 15 bytes)

01: 255 byte mode (returns peripheral data up to 255 bytes)

10: Unused (setting prohibited)

11: 0 byte mode (does not access port)

P2MD: Port 2 mode

00:15 byte mode (returns peripheral data up to 15 bytes)

01: 255 byte mode (returns peripheral data up to 255 bytes)

10: Unused (setting prohibited)

11: 0 byte mode (does not access port)

RESB: Reset button state bit

0: Reset button OFF

1: Reset button ON

It can be read regardless of the INTBACK command. (Displays the status for each V-BLANK-IN)

NPE: Presence / absence bit of remaining peripheral data

0: No data left

1: There is remaining data

PDL: Position bit of peripheral data

Peripheral data after 0: 2nd

1: 1st peripheral data

bit7

It is always 1.

● Port status

The port status is 1 byte of data that indicates the status of peripherals connected to the port. By using the port status, it is possible to determine whether the peripheral is directly connected to the corresponding port or how many taps of multi-tap are connected. Figure 3.14 shows the port status configuration.

Figure 3.14 Port status configuration

bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
Multitap ID				Number of connectors

Number of connectors

The number of connectors indicates 1H if the peripheral is directly connected to the peripheral port, indicating that one peripheral is connected to the corresponding port. If a multi-tap is connected, it indicates the number of taps for that multi-tap. Indicates 0H when nothing is connected to the peripheral port, or when a peripheral is connected to the peripheral port that SMPC does not recognize.
Table 3.5 shows the relationship between the number of connectors and the connected peripherals.

Table 3.5 Relationship between the number of connectors and peripherals

Number of connectors	Connected peripherals
0H	-Not connected-SMPC UNKOWN peripheral is connected
1H	・ The peripheral is directly connected
2H ~ FH	・ Number of multi-tap taps

Multitap ID

Multitap IDs are categorized as follows according to the connected peripherals.

1. The multitap ID indicates FH when the peripheral is directly connected to the peripheral port and when the peripheral is not connected.

2. Indicates 0H to EH when a multi-tap is connected to the peripheral port.

3. When a device (UNKNOWN device) that SMPC cannot recognize is connected to the peripheral port, it indicates the MegaDrive peripheral ID (hereinafter referred to as MD PID).

The connection judgment of the SMPC UNKNOWN device is determined by receiving an MD PID that SMPC does not support in the initial phase between the SMPC and the peripheral. When using Justy Fire (Lethal Enforcers gun) etc., it is also possible to respond by executing the connection judgment in SMPC control mode, acquiring the port status, and then using SH2 direct mode. It may also be judged as UNKNOWN when an error occurs on the line during the initial phase between the SMPC and the peripheral.

Table 3.6 Relationship between connected peripherals and multi-tap IDs

Peripheral connected to the peripheral port	Data indicated by multi-tap ID
Peripheral direct connection, unconnected	FH
Multi-tap connection	0H ~ EH
UNKNOWN device connection	MD-PID

Multitap IDs are collected separately from Saturn Peripheral IDs. The multi-tap ID is provided as a multi-tap specification.
Table 3.7 shows the currently supported multitap IDs and number of connectors.

Table 3.7 Multi-tap ID and number of connectors

Multi-tap name	Multitap ID	Number of connectors
Sega tap	0H	4H
Sega Saturn 6P multi-tap	1H	6H
Sega reservation	2H ~ EH	---