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--- title: I/O Map type: register summary: Addresses of every hardware register of the PlayStation. category: Hardware --- ## Summary The hardware registers of the PlayStation are mapped in segment X of the logical space, from 0x1F801000 to 0x1FBFFFFF, where the cache is not effective. Interface registers of the peripheral devices are mapped there as memory mapped I/O. Memory may be accessed in units of 1 to 4 bytes, but each interface register must be accessed in its own unit size, and any other size causes a bus error.[^hw24][^os25] The tables below list every register by address. psx-spx marks the names it has not found in Sony's code or documentation with a question mark, and this page keeps those marks.[^io] The I/O ports are also mirrored in KSEG1 at BF801000h, where the CPU write queue is bypassed. psx-spx therefore recommends the KSEG1 addresses for hardware with state machines such as the CD-ROM controller, although Sony's own code uses the KUSEG addresses and flushes the write queue with dummy writes.[^wq] ## Expansion and Scratchpad Table: DEV0 and scratchpad | Address | Size | Content | | --- | --- | --- | | 1F000000h | 80000h | DEV0 expansion region (default 512 KB, max 8 MB) | | 1F000000h | 100h | DEV0 expansion ROM header (IDs and entry points) | | 1F800000h | 400h | Scratchpad (1 KB fast RAM; D-cache at a fixed address) | ## System Bus Interface These registers set the base, size and timing of each bus device. The [memory control](/hardware/memory-control/) page gives their bit layouts.[^io] Table: System bus interface registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801000h | 4 | DEV0_ADDR? | DEV0 (PIO) base address | | 1F801004h | 4 | DEV8_ADDR? | DEV8 (debug) base address | | 1F801008h | 4 | DEV0_DELAY | DEV0 (PIO) delay and size | | 1F80100Ch | 4 | DEV1_DELAY | DEV1 (debug) delay and size | | 1F801010h | 4 | DEV2_DELAY | DEV2 (BIOS ROM) delay and size | | 1F801014h | 4 | DEV4_DELAY | DEV4 (SPU) delay and size | | 1F801018h | 4 | DEV5_DELAY | DEV5 (CD-ROM) delay and size | | 1F80101Ch | 4 | DEV8_DELAY | DEV8 (debug) delay and size | | 1F801020h | 4 | COM_DELAY | Common delay values | | 1F801060h | 4/2 | DRAM_CTRL? | RAM configuration | ## Peripheral I/O Ports SIO0 serves the controllers and Memory Cards, and SIO1 serves the serial port.[^io] Table: Serial interface registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801040h | 1/4 | SIO0_DR | Controller and Memory Card data (R/W) | | 1F801044h | 4 | SIO0_SR | Controller and Memory Card status (R) | | 1F801048h | 2 | SIO0_MR | Controller and Memory Card mode (R/W) | | 1F80104Ah | 2 | SIO0_CR | Controller and Memory Card control (R/W) | | 1F80104Eh | 2 | SIO0_BR | Controller and Memory Card baud rate (R/W) | | 1F801050h | 1/4 | SIO1_DR | Serial port data (R/W) | | 1F801054h | 4 | SIO1_SR | Serial port status (R) | | 1F801058h | 2 | SIO1_MR | Serial port mode (R/W) | | 1F80105Ah | 2 | SIO1_CR | Serial port control (R/W) | | 1F80105Ch | 2 | SIO1_? | Serial port internal register (R/W) | | 1F80105Eh | 2 | SIO1_BR | Serial port baud rate (R/W) | ## Interrupt Control The [interrupt controller](/hardware/interrupts/) page gives the bit layout of these two registers.[^io] Table: Interrupt control registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801070h | 2 | I_STAT | Interrupt status (I_REG) | | 1F801074h | 2 | I_MASK | Interrupt mask | ## DMA Registers Each of the 7 [DMA](/hardware/dma/) channels has three registers in a 10h-byte block. The two control registers follow the last block.[^io] Table: DMA registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801080h | 4 | D0_MADR | Channel 0 (MDECin) memory address (R/W) | | 1F801084h | 4 | D0_BCR | Channel 0 (MDECin) block count (R/W) | | 1F801088h | 4 | D0_CHCR | Channel 0 (MDECin) channel control (R/W) | | 1F801090h | 12 | D1_* | Channel 1 (MDECout) | | 1F8010A0h | 12 | D2_* | Channel 2 (GPU) | | 1F8010B0h | 12 | D3_* | Channel 3 (CD-ROM) | | 1F8010C0h | 12 | D4_* | Channel 4 (SPU) | | 1F8010D0h | 12 | D5_* | Channel 5 (PIO) | | 1F8010E0h | 12 | D6_* | Channel 6 (OTC) | | 1F8010F0h | 4 | DPCR | DMA priority control (D_PCR) | | 1F8010F4h | 4 | DICR | DMA interrupt control (D_ICR) | | 1F8010F8h | 4 | | Unknown | | 1F8010FCh | 4 | | Unknown | ## Timers The three hardware [root counters](/hardware/timers/) each have a 10h-byte block of registers.[^io] Table: Timer registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801100h | 2 | T0_COUNT | Timer 0 (dot clock) current value (R/W) | | 1F801104h | 2 | T0_MODE | Timer 0 (dot clock) mode (R/W) | | 1F801108h | 2 | T0_COMP | Timer 0 (dot clock) target value (R/W) | | 1F801110h | 12 | T1_* | Timer 1 (H-blank) | | 1F801120h | 12 | T2_* | Timer 2 (system clock) | ## CD-ROM Registers The [CD-ROM](/hardware/cd-rom/) controller has four byte-wide ports. The index in bits 0 and 1 of 1F801800h selects which register the other three ports reach, so the table gives each register as address, direction and index.[^io] Table: CD-ROM registers | Address | Access | Index | Name | Content | | --- | --- | --- | --- | --- | | 1F801800h | R | any | HSTS | Index and status register | | 1F801801h | R | any | RESULT | Response FIFO | | 1F801802h | R | any | RDDATA | Data FIFO | | 1F801803h | R | 0 | HINTMSK | Interrupt enable register | | 1F801803h | R | 1 | HINTSTS | Interrupt flag register | | 1F801800h | W | any | ADDRESS | Index register (bits 0 and 1) | | 1F801801h | W | 0 | COMMAND | Command register | | 1F801802h | W | 0 | PARAMETER | Parameter FIFO | | 1F801803h | W | 0 | HCHPCTL | Request register | | 1F801801h | W | 1 | WRDATA | Sound map data | | 1F801802h | W | 1 | HINTMSK | Interrupt enable register | | 1F801803h | W | 1 | HCLRCTL | Interrupt flag register | | 1F801801h | W | 2 | CI | Sound map coding info | | 1F801802h | W | 2 | ATV0 | Volume, left CD out to left SPU in | | 1F801803h | W | 2 | ATV1 | Volume, left CD out to right SPU in | | 1F801801h | W | 3 | ATV2 | Volume, right CD out to right SPU in | | 1F801802h | W | 3 | ATV3 | Volume, right CD out to left SPU in | | 1F801803h | W | 3 | ADPCTL | Apply volume changes (write bit 5 = 1) | ## GPU Registers The [GPU](/hardware/gpu/) has two 32-bit ports. Each has a different function for reads and writes.[^io] Table: GPU registers | Address | Access | Name | Content | | --- | --- | --- | --- | | 1F801810h | W | GP0 | GP0 commands and packets (drawing and VRAM access) | | 1F801810h | R | GP0 | Responses to GP0(C0h) and GP1(10h) | | 1F801814h | W | GP1 | GP1 commands (display control) | | 1F801814h | R | GP1 | GPU status register (GPUSTAT) | ## MDEC Registers The MDEC also has two 32-bit ports. One carries commands and data and the other carries control and status.[^io] Table: MDEC registers | Address | Access | Name | Content | | --- | --- | --- | --- | | 1F801820h | W | MDEC0 | Command and parameter register | | 1F801820h | R | MDEC0 | Data and response register | | 1F801824h | W | MDEC1 | Control and reset register | | 1F801824h | R | MDEC1 | Status register | ## SPU Registers The [SPU](/hardware/spu/) occupies 1F801C00h to 1F801FFFh. The first 180h bytes hold 8 registers for each of the 24 voices in 10h bytes per voice.[^io] Table: SPU voice registers (voice N = 0 to 23) | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801C00h + 10h x N | 2 | VOLL | Volume left | | 1F801C02h + 10h x N | 2 | VOLR | Volume right | | 1F801C04h + 10h x N | 2 | PITCH | Sample rate | | 1F801C06h + 10h x N | 2 | SSA | Sample start address | | 1F801C08h + 10h x N | 2 | ADSR1 | ADSR attack and decay | | 1F801C0Ah + 10h x N | 2 | ADSR2 | ADSR sustain and release | | 1F801C0Ch + 10h x N | 2 | ENVX | ADSR current volume | | 1F801C0Eh + 10h x N | 2 | LSAX | Loop start address | The control registers follow at 1F801D80h. Key on, key off and the per-voice modes take two registers each, one for voices 0 to 15 and one for voices 16 to 23.[^io] Table: SPU control registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801D80h | 2 | MVOLL | Main volume left | | 1F801D82h | 2 | MVOLR | Main volume right | | 1F801D84h | 2 | EVOLL | Reverb volume left | | 1F801D86h | 2 | EVOLR | Reverb volume right | | 1F801D88h | 2 | KON0 | Key on, voices 0 to 15 (W) | | 1F801D8Ah | 2 | KON1 | Key on, voices 16 to 23 (W) | | 1F801D8Ch | 2 | KOF0 | Key off, voices 0 to 15 (W) | | 1F801D8Eh | 2 | KOF1 | Key off, voices 16 to 23 (W) | | 1F801D90h | 2 | PMON0 | Pitch modulation, voices 1 to 15 (R/W) | | 1F801D92h | 2 | PMON1 | Pitch modulation, voices 16 to 23 (R/W) | | 1F801D94h | 2 | NON0 | Noise mode, voices 0 to 15 (R/W) | | 1F801D96h | 2 | NON1 | Noise mode, voices 16 to 23 (R/W) | | 1F801D98h | 2 | EON0 | Reverb mode, voices 0 to 15 (R/W) | | 1F801D9Ah | 2 | EON1 | Reverb mode, voices 16 to 23 (R/W) | | 1F801D9Ch | 2 | ENDX0 | Voice status, voices 0 to 15 (R) | | 1F801D9Eh | 2 | ENDX1 | Voice status, voices 16 to 23 (R) | | 1F801DA0h | 2 | | Unused | | 1F801DA2h | 2 | ESA | Sound RAM reverb work area start address | | 1F801DA4h | 2 | IRQA | Sound RAM IRQ address | | 1F801DA6h | 2 | TSA | Sound RAM transfer start address | | 1F801DA8h | 2 | DATA? | Sound RAM data write FIFO | | 1F801DAAh | 2 | ATTR | SPU attribute register | | 1F801DACh | 2 | RAM_CTRL? | Sound RAM size control | | 1F801DAEh | 2 | STATX | SPU status register (R) | | 1F801DB0h | 2 | AVOLL | I2SA (CD-ROM) volume left | | 1F801DB2h | 2 | AVOLR | I2SA (CD-ROM) volume right | | 1F801DB4h | 2 | BVOLL | I2SB (PIO) volume left | | 1F801DB6h | 2 | BVOLR | I2SB (PIO) volume right | | 1F801DB8h | 2 | MVOLXL | Current main volume left | | 1F801DBAh | 2 | MVOLXR | Current main volume right | | 1F801DBCh | 4 | | Unused (R/W) | The reverb configuration area holds the parameters of the reverb unit. All of its names are unofficial.[^io] Table: SPU reverb configuration area | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801DC0h | 2 | dAPF1? | APF offset 1 | | 1F801DC2h | 2 | dAPF2? | APF offset 2 | | 1F801DC4h | 2 | vIIR? | Reflection volume 1 | | 1F801DC6h | 2 | vCOMB1? | Comb volume 1 | | 1F801DC8h | 2 | vCOMB2? | Comb volume 2 | | 1F801DCAh | 2 | vCOMB3? | Comb volume 3 | | 1F801DCCh | 2 | vCOMB4? | Comb volume 4 | | 1F801DCEh | 2 | vWALL? | Reflection volume 2 | | 1F801DD0h | 2 | vAPF1? | APF volume 1 | | 1F801DD2h | 2 | vAPF2? | APF volume 2 | | 1F801DD4h | 4 | mSAME? | Same side reflection address 1, left and right | | 1F801DD8h | 4 | mCOMB1? | Comb address 1, left and right | | 1F801DDCh | 4 | mCOMB2? | Comb address 2, left and right | | 1F801DE0h | 4 | dSAME? | Same side reflection address 2, left and right | | 1F801DE4h | 4 | mDIFF? | Different side reflection address 1, left and right | | 1F801DE8h | 4 | mCOMB3? | Comb address 3, left and right | | 1F801DECh | 4 | mCOMB4? | Comb address 4, left and right | | 1F801DF0h | 4 | dDIFF? | Different side reflection address 2, left and right | | 1F801DF4h | 4 | mAPF1? | APF address 1, left and right | | 1F801DF8h | 4 | mAPF2? | APF address 2, left and right | | 1F801DFCh | 4 | vIN? | Input volume, left and right | The internal registers report the current volume of each voice:[^io] Table: SPU internal registers | Address | Size | Name | Content | | --- | --- | --- | --- | | 1F801E00h + 4h x N | 2 | VOLXL | Voice N current volume left | | 1F801E02h + 4h x N | 2 | VOLXR | Voice N current volume right | | 1F801E60h | 20h | | Unused (R/W) | | 1F801E80h | 180h | | Unused (reads FFh) | ## DEV8 Region DEV8 is an 8-bit expansion region at 1F802000h, 128 bytes by default and 8 KB at most. psx-spx reports that a 16-bit access there may crash. It holds a dual serial port for a TTY debug terminal, the DTL-H2000 ports and the POST port that shows the BIOS boot status.[^io] Table: DEV8 dual serial port | Address | Access | Content | | --- | --- | --- | | 1F802020h | 1st/2nd | DUART mode registers 1.A and 2.A (R/W) | | 1F802021h | R | DUART status register A | | 1F802021h | W | DUART clock select register A | | 1F802022h | R | DUART toggle baud rate generator test mode (strobe) | | 1F802022h | W | DUART command register A | | 1F802023h | R | DUART Rx holding register A (FIFO) | | 1F802023h | W | DUART Tx holding register A | | 1F802024h | R | DUART input port change register | | 1F802024h | W | DUART aux. control register | | 1F802025h | R | DUART interrupt status register | | 1F802025h | W | DUART interrupt mask register | | 1F802026h | R | DUART counter/timer current value, bits 15 to 8 | | 1F802026h | W | DUART counter/timer reload value, bits 15 to 8 | | 1F802027h | R | DUART counter/timer current value, bits 7 to 0 | | 1F802027h | W | DUART counter/timer reload value, bits 7 to 0 | | 1F802028h | 1st/2nd | DUART mode registers 1.B and 2.B (R/W) | | 1F802029h | R | DUART status register B | | 1F802029h | W | DUART clock select register B | | 1F80202Ah | R | DUART toggle 1X/16X test mode (strobe) | | 1F80202Ah | W | DUART command register B | | 1F80202Bh | R | DUART Rx holding register B (FIFO) | | 1F80202Bh | W | DUART Tx holding register B | | 1F80202Ch | | DUART reserved register | | 1F80202Dh | R | DUART input port | | 1F80202Dh | W | DUART output port configuration register | | 1F80202Eh | R | DUART start counter command (strobe) | | 1F80202Eh | W | DUART set output port bits (output low) | | 1F80202Fh | R | DUART stop counter command (strobe) | | 1F80202Fh | W | DUART reset output port bits (output high) | Table: DEV8 development and POST ports | Address | Size | Content | | --- | --- | --- | | 1F802000h | 1 | DTL-H2000: ATCONS STAT (R) | | 1F802002h | 1 | DTL-H2000: ATCONS DATA (R/W) | | 1F802004h | 2 | DTL-H2000: ATCONS DATA16 (R/W) | | 1F802030h | 1/4 | DTL-H2000: secondary IRQ10 flags | | 1F802032h | 1 | DTL-H2000: IRQ control | | 1F802040h | 1 | DTL-H2000: boot mode DIP switches (R) | | 1F802041h | 1 | POST: external 7-segment display of the BIOS boot status | | 1F802042h | 1 | DTL-H2000: POST/LED, 2 digits | | 1F802070h | 1 | POST2: used by the PlayStation 2 BIOS | ## DEV1 and BIOS Regions DEV1 is 1 byte by default and 2 MB at most. Neither the BIOS nor any PlayStation game uses it, although the PlayStation 2 BIOS writes its POST3 code at 1FA00000h. The BIOS ROM region is 512 KB by default and 4 MB at most, and the reset entry point is at BFC00000h.[^io] Table: DEV1 and BIOS ROM | Address | Size | Content | | --- | --- | --- | | 1FA00000h | | DEV1 (POST3 on the PlayStation 2) | | 1FC00000h | 80000h | BIOS ROM (512 KB) | ## Cache Control and Coprocessors The CW33300 core has one configuration register in KSEG2. This is BCC at FFFE0130h, and the [memory control](/hardware/memory-control/) page describes it. The coprocessors are reached by coprocessor instructions instead of addresses. COP0 (System Control Coprocessor) has 32 registers and COP2 (GTE) has 64 registers, while COP1 and COP3 do not exist.[^io] ## Access Width Most ports may be read in 8-bit, 16-bit or 32-bit units whatever their own size is. A 32-bit read of a 32-bit region that holds only one 16-bit port often returns garbage in the unused half.[^rd] Writes behave differently. An 8-bit or 16-bit store puts all 32 bits of the source register on the bus, so a narrow store to a 32-bit port such as a DMA register writes the full register value. The Soundscope of the SCPH-7000 series relies on this when it writes the DMA registers with halfword stores.[^wr] psx-spx gives the effect of each store size on each region as follows:[^ws] Table: I/O write size behavior | Address | Content | 8-bit write | 16-bit write | 32-bit write | | --- | --- | --- | --- | --- | | 00000000h to 00xFFFFFh | Main RAM | OK | OK | OK | | 1F800000h to 1F8003FFh | Scratchpad | OK | OK | OK | | 1F801000h to 1F801023h | Memory control | w32 | w32 | OK | | 1F80104xh | SIO0 | w16 | OK | Lower 16 bits | | 1F80105xh | SIO1 | w16 | OK | Lower 16 bits | | 1F801060h to 1F801063h | DRAM_CTRL | w32 | w32 | OK (crash when unaligned) | | 1F801070h to 1F801077h | Interrupt control | w32 | w32 | OK | | 1F8010x0h to 1F8010x3h | DMA address | w32 | w32 | OK | | 1F8010x4h to 1F8010x7h | DMA length | OK | OK | OK | | 1F8010x8h to 1F8010xFh | DMA control and mirror | w32 | w32 | OK | | 1F8010F0h to 1F8010F7h | DPCR and DICR | w32 | w32 | OK | | 1F8010F8h to 1F8010FFh | DMA unknown | Ignored | Ignored | Ignored | | 1F801100h to 1F80112Bh | Timers 0 to 2 | w32 | w32 | OK | | 1F801800h to 1F801803h | CD-ROM | OK | Unknown | Unknown | | 1F801810h to 1F801817h | GPU | Unknown | Unknown | OK | | 1F801820h to 1F801827h | MDEC | Unknown | Unknown | OK | | 1F801C00h to 1F801E7Fh | SPU | i16 | OK | OK | | 1F801E80h to 1F801FFFh | SPU unused | Ignored | Ignored | Ignored | | 1F802020h to 1F80202Fh | DUART | OK | Unknown | Unknown | | 1F802041h | POST | OK | Unknown | Unknown | | FFFE0130h to FFFE0133h | Cache control | i32 | i32 | OK | In this table w32 writes the full 32 bits, shifted left when the address is not word aligned, and w16 does the same with 16 bits. i32 and i16 write the full width but are ignored at an unaligned address. 16-bit writes to DRAM_CTRL, I_STAT, I_MASK and the timer registers are therefore safe.[^ws] ## Locked and Garbage Locations The gaps in the I/O region are locked, and an access there raises an exception. The same holds in KSEG0 and KSEG1:[^lk] Table: Locked regions | Address | Size | Condition | | --- | --- | --- | | 00800000h | | When main RAM ends at 7FFFFFh | | 1F080000h | 780000h | When DEV0 ends at 7FFFFh | | 1F800400h | C00h | After the scratchpad | | 1F801024h | 1Ch | I/O gap | | 1F801064h | 0Ch | I/O gap | | 1F801078h | 08h | I/O gap | | 1F801140h | 6C0h | I/O gap | | 1F801804h | 0Ch | I/O gap | | 1F801818h | 08h | I/O gap | | 1F801828h | 3D8h | I/O gap | | 1F802080h | 3FDF80h | When DEV8 ends at 7Fh | | 1FC80000h | 60380000h | When the BIOS ROM ends at 7FFFFh | | C0000000h | 1FFE0000h | KSEG2 gap | | FFFE0020h | E0h | KSEG2 gap | | FFFE0140h | 1FEC0h | KSEG2 gap | A few unused addresses inside the register blocks do not raise an exception. They hold nothing of use, and writes to them have no effect. Reads usually return zero, but the first byte of a 10h-byte block often returns the low 8 bits of its address.[^gb] Table: Garbage locations | Address | Size | Area | | --- | --- | --- | | 1F801062h | 2 | Memory and interrupt control | | 1F801072h | 2 | Memory and interrupt control | | 1F801076h | 2 | Memory and interrupt control | | 1F801102h | 2 | Timer 0 | | 1F801106h | 2 | Timer 0 | | 1F80110Ah | 6 | Timer 0 | | 1F801112h | 2 | Timer 1 | | 1F801116h | 2 | Timer 1 | | 1F80111Ah | 6 | Timer 1 | | 1F801122h | 2 | Timer 2 | | 1F801126h | 2 | Timer 2 | | 1F80112Ah | 22 | Timer 2 and after | | 1F801820h | 4 | MDEC data out, when no data is ready | | FFFE0000h | 32 | Cache control | | FFFE0100h | 48 | Cache control | | FFFE0132h | 2 | Upper half of BCC (write only) | | FFFE0134h | 12 | Cache control | When BCC bit 11 is 0, reads from these garbage addresses return the next opcode to be executed instead.[^gb] ## Legacy Names Older documents and emulators use names from nocash's original psx-spx. The current psx-spx replaces them with the official names below:[^lg] Table: Legacy register names | Legacy name | Current name | | --- | --- | | EXP1 (Expansion 1) | DEV0 | | EXP2 (Expansion 2) | DEV8 | | EXP3 (Expansion 3) | DEV1 | | JOY_TX_DATA, JOY_RX_DATA | SIO0_DR | | JOY_STAT | SIO0_SR | | JOY_MODE | SIO0_MR | | JOY_CTRL | SIO0_CR | | JOY_BAUD | SIO0_BR | | SIO_TX_DATA, SIO_RX_DATA | SIO1_DR | | SIO_STAT | SIO1_SR | | SIO_MODE | SIO1_MR | | SIO_CTRL | SIO1_CR | | SIO_MISC | SIO1_? | | SIO_BAUD | SIO1_BR | | GPUREAD | GP0 | | GPUSTAT | GP1 (the BIOS calls it GP1 when reading) | | SPUCNT | ATTR | | SPUSTAT | STATX | | DTC (Data Transfer Control) | RAM_CTRL? | | Reverb mBASE | ESA | | Reverb vLOUT, vROUT | EVOLL, EVOLR | ## References [^hw24]: Sony Computer Entertainment Inc. PlayStation Hardware. August 1998. Page 2-4, Table 2-2. [^os25]: Sony Computer Entertainment Inc. PlayStation Operating System. August 1998. Page 2-5. [^io]: psx-spx. I/O Map. https://psx-spx.consoledev.net/iomap/ [^lg]: psx-spx. I/O Map, Legacy names from outdated documentation. https://psx-spx.consoledev.net/iomap/ [^wq]: psx-spx. Memory Map, Write queue. https://psx-spx.consoledev.net/memorymap/ [^ws]: psx-spx. Unpredictable Things, I/O Write Datasize. https://psx-spx.consoledev.net/unpredictablethings/ [^rd]: psx-spx. Unpredictable Things, I/O Read Datasize. https://psx-spx.consoledev.net/unpredictablethings/ [^wr]: psx-spx. Unpredictable Things, I/O Write Datasize (8-bit and 16-bit stores). https://psx-spx.consoledev.net/unpredictablethings/ [^lk]: psx-spx. Unpredictable Things, Locked Locations in Memory and I/O Area. https://psx-spx.consoledev.net/unpredictablethings/ [^gb]: psx-spx. Unpredictable Things, Garbage Locations in I/O Area. https://psx-spx.consoledev.net/unpredictablethings/