This list shows only the internal standard I/O ports, as used in the BIOS ROM of the CPC 464/664/6128 BIOS, and in the AMSDOS ROM of the CPC 664/6128 and DDI-1. For a more complete list, including all Peripherals, see the [[I/O Port Summary|Complete I/O Port Summary]].
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== I/O Ports ==
* As components use partial address decoding, it is therefore possible to send the same value to different components '''simultaneously''' by carefully using custom I/O ports.
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== Memory Mapped I/O Ports ==
|'''Mem'''||'''Decoded as'''||'''Port'''||'''Read'''||'''Write'''
|-
|#4000-7FFF||%01xxxxxx xxxxxxxx||[[ASIC]] - CPC+/GX4000 registers|| Read || Write
|-
|}
The [[ASIC]] I/O page is defined as follows:
{|{{Prettytable|width: 700px; font-size: 2em;}}
! ADDR !! SIZE !! POR !! TYPE !! MNEM !! USE
|-
| 4000h || 100h || N || R/W || || Sprite 0 image data
|-
| 4100h || 100h || N || R/W || || Sprite 1 image data
|-
| ... || ... || ... || ... || ... || ...
|-
| 4F00h || 100h || N || R/W || || Sprite 15 image data
|-
| 5000h || || || || || (unused)
|-
| 6000h || 2 || N || R/W || X0 || Sprite 0 X position
|-
| 6002h || 2 || N || R/W || Y0 || Sprite 0 Y position
|-
| 6004h || 1 || Y || W || M0 || Sprite 0 magnification
|-
| 6005h || 3 || || || || (unused)
|-
| 6008h || 2 || N || R/W || X1 || Sprite 1 X position
|-
| 600Ah || 2 || N || R/W || Y1 || Sprite 1 Y position
|-
| 600Ch || 1 || Y || W || M1 || Sprite 1 magnification
|-
| 600Dh || 3 || || || || (unused)
|-
| ... || ... || ... || ... || ... || ...
|-
| 6078h || 2 || N || R/W || X15 || Sprite 15 X position
|-
| 607Ah || 2 || N || R/W || Y15 || Sprite 15 Y position
|-
| 607Ch || 1 || N || W || M15 || Sprite 15 magnification
|-
| 607Dh || 3 || || || || (unused)
|-
| 6080h || || || || || (unused)
|-
| 6400h || 2 || N || R/W || || Colour palette, pen 0
|-
| 6402h || 2 || N || R/W || || Colour palette, pen 1
|-
| ... || ... || ... || ... || ... || ...
|-
| 641Eh || 2 || N || R/W || || Colour palette, pen 15
|-
| 6420h || 2 || N || R/W || || Colour palette, border
|-
| 6422h || 2 || N || R/W || || Colour palette, sprite colour 1
|-
| 6424h || 2 || N || R/W || || Colour palette, sprite colour 2
|-
| ... || ... || ... || ... || ... || ...
|-
| 643Eh || 2 || N || R/W || || Colour palette, sprite colour 15
|-
| 6440h || || || || || (unused)
|-
| 6800h || 1 || Y || W || PRI || Programmable raster interrupt scan line
|-
| 6801h || 1 || Y || W || SPLT || Screen split scan line
|-
| 6802h || 2 || N || W || SSA || Screen split secondary start address
|-
| 6804h || 1 || Y || W || SSCR || Soft scroll control register
|-
| 6805h || 1 || N || W || IVR || Interrupt Vector (Bit 0 set to 1 on reset)
|-
| 6806h || || || || || (unused)
|-
| 6808h || 1 || || R || ADC0 || Analogue input channel 0
|-
| 6809h || 1 || || R || ADC1 || Analogue input channel 1
|-
| 680Ah || 1 || || R || ADC2 || Analogue input channel 2
|-
| 680Bh || 1 || || R || ADC3 || Analogue input channel 3
|-
| 680Ch || 1 || || R || ADC4 || Analogue input channel 4
|-
| 680Dh || 1 || || R || ADC5 || Analogue input channel 5
|-
| 680Eh || 1 || || R || ADC6 || Analogue input channel 6
|-
| 680Fh || 1 || || R || ADC7 || Analogue input channel 7
|-
| 6810h || || || || || (unused)
|-
| 6C00h || 2 || N || W || SAR0 || "DMA" channel 0 address pointer
|-
| 6C02h || 1 || N || W || PPR0 || "DMA" channel 0 pause prescaler
|-
| 6C03h || 1 || || || || (unused)
|-
| 6C04h || 2 || N || W || SAR1 || "DMA" channel 1 address pointer
|-
| 6C06h || 1 || N || W || PPR1 || "DMA" channel 1 pause prescaler
|-
| 6C07h || 1 || || || || (unused)
|-
| 6C08h || 2 || N || W || SAR2 || "DMA" channel 2 address pointer
|-
| 6C0Ah || 1 || N || W || PPR2 || "DMA" channel 2 pause prescaler
|-
| 6C0Bh || 4 || || || || (unused)
|-
| 6C0Fh || 1 || Y || R/W || DCSR || "DMA" control/status register
|}
POR column indicates whether a register has power on reset. A "N" indicates that the contents of a register are undefined at power on.
A colour in the palette is coded in 2 bytes:
* For first byte, bit7..4 is blue value, bit3..0 is red value
* For second byte, bit7..4 is ignored, bit3..0 is green value
Sprite magnification is coded in 1 byte:
* bit7..3 is ignored
* bit3..2 is X magnification (00 = not displayed, 01 = x1, 10 = x2, 11 = x4)
* bit1..0 is Y magnification (00 = not displayed, 01 = x1, 10 = x2, 11 = x4)
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==Internal Links==
*[[Arnold V specs]]
*[[Arnold V Specs Revised]]
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[[Category:Programming]] [[Category:CPC Internal Components]]