#### NextREG 176 (B0h) – Extended Keys 0\*

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
RIGHT Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	Key pressed status flag (1 = pressed)
LEFT Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	Key pressed status flag (1 = pressed)
DOWN Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
UP Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
. Status	■		[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
, Status	■		[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
" Status	■		[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
; Status	■		•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)

\* **NextREG 104 (68h) D4** stops extended keys from making entries into the **8x5** keyboard matrix #### NextREG 177 (B1h) – Extended Keys 1\*

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
EXTEND Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	Key pressed status flag (1 = pressed)
CAPS LOCK Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	Key pressed status flag (1 = pressed)
GRAPH Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
TRUE VIDEO Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
INV VIDEO Status	■		[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
BREAK Status	■		[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
EDIT Status	■		[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)
DELETE Status	■		•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Key pressed status flag (1 = pressed)

\* **NextREG 104 (68h) D4** stops extended keys from making entries into the **8x5** keyboard matrix #### NextREG 178 (B2h) – Extended MD Pad Buttons

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
Left pad MODE Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	Button pressed status flag (1 = pressed)
Left pad Y Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	Button pressed status flag (1 = pressed)
Left pad Z Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	Button pressed status flag (1 = pressed)
Left pad X Status	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	Button pressed status flag (1 = pressed)
Right pad MODE Status	■		[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Button pressed status flag (1 = pressed)
Right pad Y Status	■		[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Button pressed status flag (1 = pressed)
Right pad Z Status	■		[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Button pressed status flag (1 = pressed)
Right pad X Status	■		•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Button pressed status flag (1 = pressed)

#### NextREG 184 (B8) – divMMC Entry Points 0

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
0000h Automap Control	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	1 to enable automap (instruction fetch)		1
0008h Automap Control	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	1 to enable automap (instruction fetch)		1
0010h Automap Control	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	1 to enable automap (instruction fetch)
0018h Automap Control	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instruction fetch)
0020h Automap Control	■	■	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instruction fetch)
0028h Automap Control	■	■	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instruction fetch)
0030h Automap Control	■	■	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instruction fetch)
0038h Automap Control	■	■	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instruction fetch)		1

#### NextREG 185 (B9h) – divMMC Entry Points Valid 0

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
Entry point at 0000h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	1 for always*		1
Entry point at 0008h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	1 for always*		0
Entry point at 0010h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	1 for always*		0
Entry point at 0018h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	1 for always*		0
Entry point at 0020h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for always*		0
Entry point at 0028h	■	■	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for always*		0
Entry point at 0030h	■	■	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for always*		0
Entry point at 0038h	■	■	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for always*		0

\* Otherwise when ROM3 is present #### NextREG 186 (BAh) – divMMC Entry Points Timing Control 0

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
Entry point at 0000h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	1 for instant mapping otherwise delayed		0
Entry point at 0008h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	1 for instant mapping otherwise delayed		0
Entry point at 0010h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	1 for instant mapping otherwise delayed		0
Entry point at 0018h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	1 for instant mapping otherwise delayed		0
Entry point at 0020h	■	■	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for instant mapping otherwise delayed		0
Entry point at 0028h	■	■	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for instant mapping otherwise delayed		0
Entry point at 0030h	■	■	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for instant mapping otherwise delayed		0
Entry point at 0038h	■	■	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 for instant mapping otherwise delayed		0

#### NextREG 187 (BBh) – divMMC Entry Points 1

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
Entry point at 0066h (delayed)	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	1 to enable automap (instr. fetch + button)		1
Entry point at 0066h (instant)	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	1 to enable automap (instr. fetch + button)		0
Entry point at 04C6h (ROM3)¹	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	1 to enable automap (instr. fetch/delayed)		1
Entry point at 0562h (ROM3)¹	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instr. fetch/delayed)		1
Entry point at 04D7h (ROM3)²	■	■	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instr. fetch/delayed)		0
Entry point at 056Ah (ROM3)²	■	■	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instr. fetch/delayed)		0
Entry points at 1FF8h:1FFFh	■	■	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to disable automap (instr. fetch/delayed)		1
Entry points at 3Dxxh (ROM3)³	■	■	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable automap (instr. fetch/instant)		1

1 Tape traps. Original divMMC + esxDOS\ 2 Tape traps. NextZXOS (these offer better compatibility with tape-based software)\ 3 Used by TR-DOS ### INTERRUPTS #### NextREG 192 (C0h) – Interrupt Control

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
Maskable Interrupt Mode	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	[colour: pink]	[colour: pink]	[colour: pink]	0	Pulse		0
Current Z80 Interrupt Mode	■		[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	[colour: pink]	0	0	[colour: pink]	Interrupt Mode 0		0
			[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	[colour: pink]	0	1	[colour: pink]	Interrupt Mode 1
			[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	[colour: pink]	1	0	[colour: pink]	Interrupt Mode 2
Stackless NMI Enable¹	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	•	[colour: pink]	[colour: pink]	[colour: pink]	Toggle (1=enable, 0=disable)		0
Reserved	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green] 0	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Reserved, must be 0		0
IM2 vector	■	■	•	•	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Programmable portion of IM2 vector		0
Maskable Interrupt Mode	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1	Hardware IM2²		0
Interrupt Vector Generated	■	■	[colour: pink]	[colour: pink]	[colour: pink]	.0	0	0	0	[colour: pink]	Line interrupt (Highest Priority)
			[colour: pink]	[colour: pink]	[colour: pink]	0	0	0	1	[colour: pink]	UART 0 Rx
			[colour: pink]	[colour: pink]	[colour: pink]	0	0	1	0	[colour: pink]	UART 1 Rx
			[colour: pink]	[colour: pink]	[colour: pink]	0	0	1	1	[colour: pink]	CTC Channel 0
			[colour: pink]	[colour: pink]	[colour: pink]	0	1	0	0	[colour: pink]	CTC Channel 1
			[colour: pink]	[colour: pink]	[colour: pink]	0	1	0	1	[colour: pink]	CTC Channel 2
			[colour: pink]	[colour: pink]	[colour: pink]	0	1	1	0	[colour: pink]	CTC Channel 3
			[colour: pink]	[colour: pink]	[colour: pink]	0	1	1	1	[colour: pink]	CTC Channel 4
			[colour: pink]	[colour: pink]	[colour: pink]	1	0	0	0	[colour: pink]	CTC Channel 5
			[colour: pink]	[colour: pink]	[colour: pink]	1	0	0	1	[colour: pink]	CTC Channel 6
			[colour: pink]	[colour: pink]	[colour: pink]	1	0	1	0	[colour: pink]	CTC Channel 7
			[colour: pink]	[colour: pink]	[colour: pink]	1	0	1	1	[colour: pink]	ULA
			[colour: pink]	[colour: pink]	[colour: pink]	1	1	0	0	[colour: pink]	UART 0 Tx
			[colour: pink]	[colour: pink]	[colour: pink]	1	1	0	1	[colour: pink]	UART 1 Tx (lowest priority)
			•	•	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	NextREG 192 (C0h) D7:D5

1 The return address pushed during an **NMI** acknowledge cycle will be written to **NextREG** instead of memory (the **SP** will be decremented) and the first **RETN** after the acknowledge will take its return address from **NextREG** instead of memory (the **SP** will be incremented)\ If D3 = 0 and in other circumstances (see advanced hardware manual), **RETN** functions normally\ 2 In Hardware IM2 Mode the expansion bus is the lowest priority interrupter and if no vector is supplied externally then **255 (FFh)** will be generated #### NextREG 194 (C2h) – NMI Return Address LSB

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
NMI Return Address	■	■	•	•	•	•	•	•	•	•	8-bit value (LSB)		*

The return address written during an **NMI** acknowledge cycle is always stored in this and the next (**NextREG C3h**) registers #### NextREG 195 (C3h) – NMI Return Address MSB

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
NMI Return Address	■	■	•	•	•	•	•	•	•	•	8-bit value (MSB)		*

The return address written during an **NMI** acknowledge cycle is always stored in this and the previous (**NextREG C2h**) registers #### NextREG 196 (C4h) – Interrupt Enables 0

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
ULA	■	■	[colour: pink]	[colour: dark green]	[colour: dark green]	[colour: dark green]	[colour: dark green]	[colour: dark green]	[colour: pink]	•	1 to enable*		1
Line	■	■	[colour: pink]	[colour: dark green]	[colour: dark green]	[colour: dark green]	[colour: dark green]	[colour: dark green]	•	[colour: pink]	1 to enable*		0
Reserved	■	■	[colour: pink]	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: pink]	[colour: pink]	Reserved must be 0		0
Expasion Bus I̅N̅T̅	■	■	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		1

\* Aliases of interrupt enable bits in **NextREG 34 (22h)**\ If a device interrupt is disabled, it enters a polled mode #### NextREG 197 (C5h) – Interrupt Enables 1

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
CTC Channel 0 ZC/TO	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	1 to enable		0
CTC Channel 1 ZC/TO	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	1 to enable		0
CTC Channel 2 ZC/TO	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	1 to enable		0
CTC Channel 3 ZC/TO	■	■	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
CTC Channel 4 ZC/TO	■	■	[colour: pink]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
CTC Channel 5 ZC/TO	■	■	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
CTC Channel 6 ZC/TO	■	■	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
CTC Channel 7 ZC/TO	■	■	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0

If a device interrupt is disabled, it enters a polled mode #### NextREG 198 (C6h) – Interrupt Enables 2

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
UART 0 Rx available¹	■	■	[colour: dark green]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	[colour: pink]	[colour: pink]	•	1 to enable		0
UART 0 Rx near-full¹	■	■	[colour: dark green]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	[colour: pink]	•	[colour: pink]	1 to enable		0
UART 0 Tx empty	■	■	[colour: dark green]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green]	•	[colour: pink]	[colour: pink]	1 to enable		0
Reserved	■	■	[colour: dark green]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: dark green] 0	[colour: pink]	[colour: pink]	[colour: pink]	Reserved, must be 0		0
UART 1 Rx available²	■	■	[colour: dark green]	[colour: pink]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
UART 1 Rx near-full²	■	■	[colour: dark green]	[colour: pink]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
UART 1 Tx empty	■	■	[colour: dark green]	•	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	1 to enable		0
Reserved	■	■	[colour: dark green] 0	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	[colour: pink]	Reserved, must be 0		0

1 Shared interrupt. **Rx near-full** overrides **Rx available**\ 2 Shared interrupt. **Rx near-full** overrides **Rx available**\ If a device interrupt is disabled, it enters a polled mode #### NextREG 199 (C7h) – Reserved

Group Name	R	W	Data Bits								Description	H	D
			7	6	5	4	3	2	1	0
Reserved, write 0	■	■	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	[colour: dark green] 0	Reserved, must be 0		0