I/O Port Summary

This is a list of all known I/O ports of the Amstrad CPC, including all Peripherals. For a list showing only the built-in standard addresses see Default I/O Port Summary.

I/O	Decoded as	Port	Read	Write
#1C00	%x0xxxx00 xxxxxxxx	Dk'tronics Lightpen faulty mirror of #BCXX CRTC Index	-	Write
#1F00	%x0xxxx11 xxxxxxxx	Dk'tronics Lightpen faulty mirror of #BFXX CRTC Data In	Read	-
#78XX	?	4Mb Memory extension	-	Write
#79XX	?	4Mb Memory extension	-	Write
#7AXX	?	4Mb Memory extension	-	Write
#7BXX	?	4Mb Memory extension	-	Write
#7CXX	?	4Mb Memory extension	-	Write
#7CXX	%0xxxxx00 xxxxxxxx	Aleste 520EX RAM Mapper page 0 (extended "Gate Array 3")	Read	Write
#7DXX	?	4Mb Memory extension	-	Write
#7DXX	%0xxxxx01 xxxxxxxx	Aleste 520EX RAM Mapper page 1 (extended "Gate Array 3")	Read	Write
#7EXX	?	4Mb Memory extension	-	Write
#7EXX	%0xxxxx10 xxxxxxxx	Aleste 520EX RAM Mapper page 2 (extended "Gate Array 3")	Read	Write
#7FXX	?	4Mb Memory extension	-	Write
#7FXX	%0xxxxx11 xxxxxxxx	Aleste 520EX RAM Mapper page 3 (extended "Gate Array 3")	Read	Write
#7FXX	?	Dk'tronics memory expansion	-	Write
#7FXX	?	Dobbertin Memory Expansion	-	Write
#7FXX	%01xxxxxx xxxxxxxx	Gate Array	-	Write
#7FXX	%0xxxxxxx xxxxxxxx	PAL extension to Gate Array for 128K RAM banking	-	Write
#BCXX	%x0xxxx00 xxxxxxxx	6845 CRTC Index	-	Write
#BDXX	%x0xxxx01 xxxxxxxx	6845 CRTC Data Out	-	Write
#BEXX	%x0xxxx10 xxxxxxxx	6845 CRTC Status (as far as supported)	Read	-
#BFXX	%x0xxxx11 xxxxxxxx	6845 CRTC Data In (as far as supported)	Read	-
#DFXX	%xx0xxxxx xxxxxxxx	Upper ROM Bank Number	-	Write
#ECXX	%xxx0xx00 xxxxxxxx	KC Compact CIO Port B (timer)	Read	Write
#EDXX	%xxx0xx01 xxxxxxxx	KC Compact CIO Port C (timer)	Read	Write
#EEXX	%xxx0xx10 xxxxxxxx	KC Compact CIO Control	Read	Write
#EEXX	%xxx0xxx0 xxxxxxxx	Aleste 520EX USART 8251 (RS232/Mouse) Data	Read	Write
#EFXX	%xxx0xx11 xxxxxxxx	KC Compact CIO Port A (Bi-drectional Printer Port)	Read	Write
#EFXX	%xxx0xxx1 xxxxxxxx	Aleste 520EX USART 8251 (RS232/Mouse) Control/Status	Read	Write
#EFXX	%xxx0xxxx xxxxxxxx	Printer Port	-	Write
#F4XX	%xxxx0x00 xxxxxxxx	8255 PIO Port A (PSG Data)	Read	Write
#F5XX	%xxxx0x01 xxxxxxxx	8255 PIO Port B (Vsync,PrnBusy,Tape,etc.)	Read	-
#F6XX	%xxxx0x10 xxxxxxxx	8255 PIO Port C (KeybRow,Tape,PSG Control)	-	Write
#F7XX	%xxxx0x11 xxxxxxxx	8255 PIO Control-Register	-	Write
#F8B0	?	Vidi-CPC Video-Digitiser	?	?
#F8B1	?	Vidi-CPC Video-Digitiser	?	?
#F8DC	?	CPCI Serial Interface MC6850 Control/Status	Read	Write
#F8DD	?	CPCI Serial Interface MC6850 Data	Read	Write
#F8E0	?	DHCP MIDI Interface	Read	Write
#F8E0	?	Schneider RS232 Interface Z80 STI Indirect Data Register	Read	Write
#F8E1	?	Schneider RS232 Interface Z80 STI Gen. Purpose I/O Interrupt	Read	Write
#F8E6	?	Port A - IDE8255	?	?
#F8E7	?	Port C - IDE8255	?	?
#F8E8	?	Schneider RS232 Interface Z80 STI Pointer Vector Register	Read	Write
#F8E8	?	Music Machine Interrupt Sel	-	Write
#F8EC	?	Schneider RS232 Interface Z80 STI USART Control Register	Read	Write
#F8EC	?	Music Machine ACIA Control	-	Write
#F8ED	?	Music Machine ACIA Data Write	-	Write
#F8ED	?	Schneider RS232 Interface Z80 STI Receiver Status Register	Read	Write
#F8EE	?	Music Machine ACIA Status	Read	-
#F8EE	?	Schneider RS232 Interface Z80 STI Transmitter Status Register	Read	Write
#F8EF	?	Schneider RS232 Interface Z80 STI USART Data Register	Read	Write
#F8EF	?	Music Machine ACIA Data Read	Read	-
#F8E2 - #F8E4	?	Dobbertin Eprommer 4003	?	?
#F8F0	?	Music Machine DAC Write	-	Write
#F8F2	?	EMR MIDI Interface	-	Write
#F8F2	?	Dobbertin Eprommer 4003	?	?
#F8F4	?	Music Machine ADC Read	Read	-
#F8F8	?	Music Machine ADC Start	-	Write
#F8FF	%1111100x 111xxxxx	CPCISA control port	-	Write
#F8FF	N/A	Peripheral Soft Reset (MC_BOOT_PROGRAM and MC_START_PROGRAM do OUT [F8FF],FF)	-	Write
#F9B0	?	Vidi-CPC Video-Digitiser	?	?
#F9E6	?	Port B - IDE8255	?	?
#F9E7	?	RS Port - IDE8255	?	?
#F9F7	?	Hegotron grafpad II	?	?
#F9FC - #F9FE	?	Otten & Fecht 1 MB RAM-Disc	Read	Write
#F9FF	?	Hegotron grafpad II	?	?
#FA7E	%xxxxx0x0 0xxxxxxx	Floppy Motor Control (for 765 FDC)	-	Write
#FABF	%xxxxx0x0 10xxxxxx	Aleste 520EX EXTPORT (config for internal hardware)	-	Write
#FADC	?	Amstrad Serial Interface Z80-SIO / DART port A Data Register	Read	Write
#FADD	?	Amstrad Serial Interface Z80-SIO / DART port A Control Reg.	Read	Write
#FADE	?	Amstrad Serial Interface Z80-SIO / DART port B Data Register	Read	Write
#FADF	?	Amstrad Serial Interface Z80-SIO / DART port B Control Reg.	Read	Write
#FAE6	?	Port A - IDE8255	?	?
#FAE7	?	Port C - IDE8255	?	?
#FAEE	?	Amstrad SSA-1 Speech Synthesizer (faulty mirror used by included RSX driver)	Read	Write
#FB7E	%xxxxx0x1 0xxxxxx0	765 FDC (internal) Status Register	Read	-
#FB7F	%xxxxx0x1 0xxxxxx1	765 FDC (internal) Data Register	Read	Write
#FBBD	?	Ram select mode Vortex SP512	?	Write
#FBDC	?	Amstrad Serial Interface 8253 Timer counter 0	Read	Write
#FBDD	?	Amstrad Serial Interface 8253 Timer counter 1	Read	Write
#FBDE	?	Amstrad Serial Interface 8253 Timer counter 2	Read	Write
#FBDF	?	Amstrad Serial Interface 8253 Timer Modus Select	-	Write
#FBxx+0	?	CPCI Real Time Clock Index (DIY)	-	Write
#FBxx+1	?	CPCI Real Time Clock Data (DIY)	Read	Write
#FBE0 - #FBE3	?	Dk'tronics Real Time Clock	?	?
#FBE0	?	Dobbertin Harddisc Data Port	Read	Write
#FBE1	?	Dobbertin Harddisc Status, Reset	Read	Write
#FBE2	?	Dobbertin Harddisc Select, Configuration	Read	Write
#FBE3	?	Dobbertin Harddisc DMA, Interrupt	Read	Write
#FBE4	?	Dobbertin Harddisc Reset	Read	Write
#FBE6	?	Port B - IDE8255	?	?
#FBE7	?	RS Port - IDE8255	?	?
#FBE7	?	ACU Real Time Clock (DIY) Z80-PIO Data In/Out Port A	Read	Write
#FBE8	?	Dk'tronics Real Time Clock	?	?
#FBE8	?	KDS RS232 8253 Timer0 (RX Clock)	Read	Write
#FBE9	?	KDS RS232 8253 Timer1 (TX Clock)	Read	Write
#FBEA	?	KDS RS232 8253 Timer2 (not used)	Read	Write
#FBEB	?	KDS RS232 8253 Timer Control	-	Write
#FBEC	?	KDS RS232 6850 (reversed bit-order) Control	-	Write
#FBED	?	KDS RS232 6850 (reversed bit-order) TX Data	-	Write
#FBEE	?	Amstrad SSA-1 Speech Synthesizer	Read	Write
#FBEE	?	KDS RS232 6850 (reversed bit-order) Status	Read	-
#FBEF	?	KDS RS232 6850 (reversed bit-order) RX Data	Read	-
#FBEF	?	ACU Real Time Clock (DIY) Z80-PIO Data In/Out Port B	Read	Write
#FBF0 - #FBFF	?	Otten & Fecht 1 MB RAM-Disc	Read	Write
#FBF6	?	Vortex Disc Drives 765 FDC (Vortex,ext) Status Register	Read	-
#FBF7	?	Vortex Disc Drives 765 FDC (Vortex,ext) Data Register	Read	Write
#FBF7	?	ACU Real Time Clock (DIY) Z80-PIO Configure Port A	Read	Write
#FBFE	?	Magnum Light Phaser	-	Write
#FBFE	?	Dk'tronics Speech Synthesizer	Read	Write
#FBFE	?	TMPI speech synthesizer Data Register		Write
#FBFF	?	TMPI speech synthesizer Command/Status Register	Read	Write
#FBFF	?	ACU Real Time Clock (DIY) Z80-PIO Configure Port B	Read	Write
#FC00 - #FDFF	%1111110x xxxxxxxx	CPCISA 16bits mode high byte latch	Read	Write
#FCE6	?	Port A - IDE8255	Read	Write
#FCE7	?	Port C - IDE8255	Read	Write
#FD00 - #FD3F	%11111101 00xxxxxx	SYMBiFACE II	Read	Write
#FDE6	?	Port B - IDE8255	Read	Write
#FDE7	?	RS Port - IDE8255	Read	Write
#FE00 - #FFFF	%1111111x xxxxxxxx	CPCISA I/O access (low byte)	Read	Write
#FEE6	?	Port A - IDE8255	Read	Write
#FEE7	?	Port C - IDE8255	Read	Write
#FEE8	?	Multiface II	?	?
#FEEA	?	Multiface II	?	?
#FFXX	%11111111 xxxxxxxx	CPC Booster (XX=#00..#28 are used now)	Read	Write
#FFXX	%11111111 xxxxxxxx	Amdrum (unsigned 8bit DAC)	-	Write
#FFE6	?	Port B - IDE8255	Read	Write
#FFE7	?	RS Port - IDE8255	Read	Write

CPCISA ports for ISA cards

Device	PC I/O range	CPCISA high	CPCISA low
IDE1	1F0h..1F7h	#FDF0..#FDF7	#FFF0..#FFF7
IDE2	170h..177h	#FD70..#FD77	#FF70..#FF77
Joystick	201h..201h	#FC01..#FC01	#FE01..#FE01
Ethernet	210h..21Fh	#FC10..#FC1F	#FE10..#FE1F
Sound Blaster	220h..23Fh	#FC20..#FC3F	#FE20..#FE3F
LPT2	278h..27Fh	#FC78..#FC7F	#FE78..#FE7F
COM1	2F8h..2FFh	#FCF8..#FCFF	#FEF8..#FEFF
MIDI'	300h..301h	#FD00..#FD01	#FF00..#FF01
MIDI	330h..331h	#FD30..#FD31	#FF30..#FF31
Sound control	370h..371h	#FD70..#FD71	#FF70..#FF71
FDC1	372h..377h	#FD72..#FD77	#FF72..#FF77
LPT1	378h..37Fh	#FD78..#FD7F	#FF78..#FF7F
Sound AD-LIB	388h..38Bh	#FD88..#FD8B	#FF88..#FF8B
VGA	3B0h..3BBh	#FDB0..#FDBB	#FFB0..#FFBB
LPT3	3BCh..3BFh	#FDBC..#FDBF	#FFBC..#FFBF
VGA	3C0h..3DFh	#FDC0..#FDCF	#FFC0..#FFCF
FDC1	3F2h..3F7h	#FDF2..#FDF7	#FFF2..#FFF7
COM1	3F8h..3FFh	#FDF8..#FDFF	#FFF8..#FFFF

CPCISA ports for ISA motherboard

Device	PC I/O range	CPCISA high	CPCISA low
DMA	000h..00Fh	#FC00..#FC0F	#FE00..#FE0F
interrupt	020h..03Fh	#FC20..#FC3F	#FE20..#FE3F
counter	040h..05Fh	#FC40..#FC5F	#FE40..#FE5F
keyboard	060h..067h	#FC60..#FC67	#FE60..#FE67
RTC	070h..071h	#FC70..#FC71	#FE70..#FE71
DMA	080h..08Fh	#FC80..#FC8F	#FE80..#FE8F
DMA	0C0h..0DFh	#FCC0..#FCDF	#FEC0..#FEDF
interrupt	0A0h..0BFh	#FCA0..#FCBF	#FEA0..#FEBF