| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| X Coordinate LSB | | ■ | • | • | • | • | • | • | • | • | Sprite X Coordinate LSB | | |
Same as NextREG 53 (35h) but writes also auto-increment the sprite number
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Y Coordinate LSB | | ■ | • | • | • | • | • | • | • | • | Sprite Y Coordinate LSB | | |
Same as NextREG 54 (36h) but writes also auto-increment the sprite number
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Sprite Attribute 2 | | ■ | e | e | e | e | d | c | b | a | See notes | | |
a,b,c,d,e: Same as NextREG 55 (37h) but writes also auto-increment the sprite number
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Sprite Attribute 3 | | ■ | c | b | a | a | a | a | a | a | See notes | | |
a,b,c: Same as NextREG 56 (38h) but writes also auto-increment the sprite number
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Sprite Attribute 4 | | ■ | f | e | d | c | c | b | b | a | See notes | | |
a,b,c,d,e,f: Same as NextREG 57 (39h) but writes also auto-increment the sprite number
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| User Register | ■ | ■ | • | • | • | • | • | • | • | • | User Register | | * |
* Soft reset defaults to 255 (FFh)
CAUTION: NextREG numbers above 127 (7Fh) are inaccessible to the Copper
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| AFTER SOFT RESET (Copied into bits D4 through D7) |
| Memory Cycles and R̅O̅M̅C̅S̅ | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Memory cycles Disable/ Ignore R̅O̅M̅C̅S̅ | ■ | 0 |
| I/O Cycles and I̅O̅R̅Q̅U̅L̅A̅ | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | I/O cycles Disable / Ignore I̅O̅R̅Q̅U̅L̅A̅ | ■ | 0 |
| divMMC R̅O̅M̅C̅S̅ ROM Enable | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | ROM from divMMC banks 14/15 Enable | ■ | 0 |
| Expansion bus Enable | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Expansion bus Enable | ■ | 0 |
| IMMEDIATE |
| Memory Cycles and R̅O̅M̅C̅S̅ | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Memory cycles Disable/ Ignore R̅O̅M̅C̅S̅ | ■ | 0 |
| I/O Cycles and I̅O̅R̅Q̅U̅L̅A̅ | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | I/O cycles Disable / Ignore I̅O̅R̅Q̅U̅L̅A̅ | ■ | 0 |
| divMMC R̅O̅M̅C̅S̅ ROM Enable | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | ROM from divMMC banks 14/15 Enable | ■ | 0 |
| Expansion bus Enable | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Expansion bus Enable | ■ | 0 |
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| MAX CPU Speed when Expansion Bus is enabled¹ | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | 0 | 0 | 3.5 MHz | ■ | * |
| colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | 0 | 1 | 7 MHz |
| colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | 1 | 0 | 14 MHz |
| colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | 1 | 1 | 28 MHz |
| Propagate MAX CPU Clock ena. | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Propagate MAX CPU Clock at all times² | ■ | 0 |
| Disable Exp.Bus NMI Debounce | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Disables the NMI debounce³ | ■ | 0 |
| ULA override control | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Allows peripherals to override ULA⁴ | ■ | 0 |
| Exp. bus R̅O̅M̅C̅S̅ state flag | ■ | | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | R̅O̅M̅C̅S̅ asserted on Expansion Bus | ■ | 0 |
* Hard reset defaults to 00
¹ Currently fixed at 00
² Applies even when the Expansion Bus is disabled
³ A value of 1 disables the Expansion BSus' NMI debounce as required by some peripherals like the Opus Discovery
⁴ A value of 1 allows peripherals to override the ULA on even port reads as equired by some peripherals like the Rotronics Wafadrive
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable Timex | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Port FFh | | 1 |
| Enable Paging | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Port 7FFDh | | 1 |
| Enable Next Memory Paging | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Port DFFDh | | 1 |
| Enable +3 Paging | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Port 1FFDh | | 1 |
| Enable +3 Floating Bus | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | +3 Floating bus | | 1 |
| Enable DMA | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 6Bh (DMA) | | 1 |
| Enable Kempston Port 1 | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 1Fh (Kempston / MD 1) | | 1 |
| Enable Kempston Port 2 | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 37h (Kempston / MD 2) | | 1 |
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable divMMC | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Port E3h (divMMC Control) | | 1 |
| Enable Multiface | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Multiface (two variable ports) | | 1 |
| Enable I²C | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Ports 103Bh, 113Bh (I²C) | | 1 |
| Enable SPI | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Ports E7h, EBh (SPI) | | 1 |
| Enable UART | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Ports 133Bh, 143Bh, 153Bh,163Bh (UART) | | 1 |
| Enable Kempston Mouse | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Ports FADFh,FBDFh,FFDFh mouse* | | 1 |
| Enable Sprites | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Ports 57h,5Bh,303Bh (Sprites) | | 1 |
| Enable Layer 2 | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 123Bh (Layer2) | | 1 |
* Also disables Kempston alias on port DFh
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable AY | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Ports FFFDh, BFFDh (AY) | | 1 |
| Enable Soundrive DAC Mode 1 | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Ports 0Fh,1Fh, 4Fh, 5Fh (DAC SD1) | | 1 |
| Enable Soundrive DAC Mode 2 | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Ports F1h, F3h, F9h ,FBh (DAC SD2) | | 1 |
| Enable Profi/Covox Stereo DAC | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Ports 3Fh, 5Fh (DAC stereo-Profi/Covox) | | 1 |
| Enable Covox Stereo DAC | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Ports 0Fh, 4Fh (DAC stereo-Covox) | | 1 |
| Enable Pentagon/ATM DAC | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port FBh (DAC mono-Pentagon) (SD2 off) | | 1 |
| Enable Covox/GS Mono DAC | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port B3h (DAC mono-GS/Covox) | | 1 |
| Enable SPECdrum Mono DAC | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port DFh (DAC mono-SPECdrum)* | | 1 |
* Also a Kempston port 1Fh alias
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable ULAplus | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Ports BF3Bh, FF3Bh (ULAplus) | ■ | 1 |
| Enable DMA | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Port 0Bh (Z80DMA) | ■ | 1 |
| Enable Pentagon 1024 Memory | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Port EFF7h (Pentagon 1024 memory) | ■ | 0 |
| Enable CTC | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Ports 183Bh - 1F3Bh (CTC Channels 0-7) | ■ | 1 |
| Register Reset | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Register reset mode (soft or hard reset sel.) | | |
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable Timex | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Port FFh | ■ | 1 |
| Enable Paging | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Port 7FFDh | ■ | 1 |
| Enable Next Memory Paging | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Port DFFDh | ■ | 1 |
| Enable +3 Paging | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Port 1FFDh | ■ | 1 |
| Enable +3 Floating Bus | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | +3 Floating bus | ■ | 1 |
| Enable DMA | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 6Bh (DMA) | ■ | 1 |
| Enable Kempston Port 1 | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 1Fh (Kempston / MD 1) | ■ | 1 |
| Enable Kempston Port 2 | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 37h (Kempston / MD 2) | ■ | 1 |
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable divMMC | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Port E3h (divMMC Control) | ■ | 1 |
| Enable Multiface | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Multiface (two variable ports) | ■ | 1 |
| Enable I²C | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Ports 103Bh, 113Bh (I²C) | ■ | 1 |
| Enable SPI | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Ports E7h, EBh (SPI) | ■ | 1 |
| Enable UART | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Ports 133Bh, 143Bh, 153Bh, 163Bh(UART) | ■ | 1 |
| Enable Kempston Mouse | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Ports FADFh,FBDFh,FFDFh mouse¹ | ■ | 1 |
| Enable Sprites | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Ports 57h,5Bh,303Bh (Sprites) | ■ | 1 |
| Enable Layer 2 | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port 123Bh (Layer2) | ■ | 1 |
1 Also disables Kempston alias on port DFh
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable AY | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Ports FFFDh, BFFDh (AY) | ■ | 1 |
| Enable DAC Mode 1 | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Ports 0Fh,1Fh, 4Fh, 5Fh (DAC mode 1) | ■ | 1 |
| Enable DAC Mode 2 | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Ports F1h, F3h, F9h ,FBh (DAC mode 2) | ■ | 1 |
| Enable Profi/Covox Stereo DAC | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Ports 3Fh, 5Fh (DAC stereo-Profi/Covox) | ■ | 1 |
| Enable Covox Stereo DAC | ■ | ■ | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Ports 0Fh, 4Fh (DAC stereo-Covox) | ■ | 1 |
| Enable Pentagon/ATM DAC | ■ | ■ | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port FBh (DAC mono Pentagon) (SD2 off) | ■ | 1 |
| Enable Covox/GS Mono DAC | ■ | ■ | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port B3h (DAC mono GS/Covox) | ■ | 1 |
| Enable SPECdrum Mono DAC | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Port DFh (DAC mono SPECdrum)¹ | ■ | 1 |
1 Also alias of Kempston port 1Fh
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Enable ULAplus | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Ports BF3Bh, FF3Bh (ULAplus) | ■ | 1 |
| Enable DMA | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Port 0Bh (Z80DMA) | ■ | 1 |
| Enable Pentagon 1024 Memory | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Port EFF7h (Pentagon 1024 memory) | ■ | 0 |
| Enable CTC | ■ | ■ | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Ports 183Bh - 1F3Bh (CTC Channels 0-7) | ■ | 1 |
| Register Reset | ■ | ■ | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Register reset mode (soft or hard reset sel.) | | |
The Internal Port Decoding Enables always apply.
When the Expansion Bus is enabled, the Expansion Bus Port Decoding Enables are logically ANDed with the Internal Enables. A result of 0 for the corresponding bit indicates the internal device is disabled. If the Expansion Bus is enabled, this allows I/O cycles for disabled ports to propagate to the Expansion Bus, otherwise corresponding I/O cycles to the Expansion Bus are filtered.
| Group Name | R | W | Data Bits | Description | H | D |
|---|
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
|---|
| Port FEh | ■ | ■ | colour: dark green | colour: dark green | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | • | Propagate port FEh I/O Cycles | ■ | 0 |
| Port 7FFDh | ■ | ■ | colour: dark green | colour: dark green | colour: pink | colour: pink | colour: pink | colour: pink | • | colour: pink | Propagate port 7FFDh I/O Cycles | ■ | 0 |
| Port DFFDh | ■ | ■ | colour: dark green | colour: dark green | colour: pink | colour: pink | colour: pink | • | colour: pink | colour: pink | Propagate port DFFDh I/O Cycles | ■ | 0 |
| Port 1FFDh | ■ | ■ | colour: dark green | colour: dark green | colour: pink | colour: pink | • | colour: pink | colour: pink | colour: pink | Propagate port 1FFDh I/O Cycles | ■ | 0 |
| Port FFh | ■ | ■ | colour: dark green | colour: dark green | colour: pink | • | colour: pink | colour: pink | colour: pink | colour: pink | Propagate port FFh I/O Cycles | ■ | 0 |
| Port EFF7h | ■ | ■ | colour: dark green | colour: dark green | • | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Propagate port EFF7h I/O Cycles | ■ | 0 |
| Reserved | ■ | ■ | colour: dark green 0 | colour: dark green 0 | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | colour: pink | Reserved, must be 0 | ■ | 0 |
If any of the bits are set, I/O cycles for the corresponding ports are propagated to the Expansion Bus when the Expansion Bus is enabled. If the internal port decode is still active, any response sent by devices on the Expansion Bus will be ignored
This allows external peripherals to monitor changes in state inside the ZX Spectrum Next. Port FEh is treated specially, so that external keyboards can be attached. When its propagate bit is set, the value read from the bus will be mixed into keyboard reads on port FEh