Difference between revisions of "Default I/O Port Summary"

From CPCWiki - THE Amstrad CPC encyclopedia!
Jump to: navigation, search
(→‎I/O Port Mapping)
(→‎Memory Mapped I/O Ports)
 
(33 intermediate revisions by the same user not shown)
Line 1: Line 1:
 
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]].
 
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]].
  
−
== I/O Port Mapping ==
+
<br>
−
 
+
−
{|{{Prettytable|width: 700px; font-size: 2em;}}
+
−
|'''Hardware device'''||'''Address'''||'''Read/Write'''||'''b15'''||'''b14'''||'''b13'''||'''b12'''||'''b11'''||'''b10'''||'''b9'''||'''b8'''||'''b7'''||'''b6'''||'''b5'''||'''b4'''||'''b3'''||'''b2'''||'''b1'''||'''b0'''
+
−
|-
+
−
|Gate Array||&7F||Write Only||0||1||-||-||-||-||-||-||-||-||-||-||-||-||-||-
+
−
|-
+
−
|PAL||&7F||Write Only||0||-||-||-||-||-||-||-||-||-||-||-||-||-||-||-
+
−
|-
+
−
|CRTC Select||&BC||Write Only||-||0||-||-||-||-||0||0||-||-||-||-||-||-||-||-
+
−
|-
+
−
|CRTC Write||&BD||Write Only||-||0||-||-||-||-||0||1||-||-||-||-||-||-||-||-
+
−
|-
+
−
|CRTC Status||&BE||Read Only||-||0||-||-||-||-||1||0||-||-||-||-||-||-||-||-
+
−
|-
+
−
|CRTC Read||&BF||Read Only||-||0||-||-||-||-||1||1||-||-||-||-||-||-||-||-
+
−
|-
+
−
|ROM select||&DF||Write Only||-||-||0||-||-||-||-||-||-||-||-||-||-||-||-||-
+
−
|-
+
−
|Printer port||&EF||Write Only||-||-||-||0||-||-||-||-||-||-||-||-||-||-||-||-
+
−
|-
+
−
|PPI Port A||&F4||Read/Write||-||-||-||-||0||-||0||0||-||-||-||-||-||-||-||-
+
−
|-
+
−
|PPI Port B||&F5||Read/Write||-||-||-||-||0||-||0||1||-||-||-||-||-||-||-||-
+
−
|-
+
−
|PPI Port C||&F6||Read/Write||-||-||-||-||0||-||1||0||-||-||-||-||-||-||-||-
+
−
|-
+
−
|PPI Control||&F7||Write Only||-||-||-||-||0||-||1||1||-||-||-||-||-||-||-||-
+
−
|-
+
−
|FDC Status||&FB||Read Only||-||-||-||-||-||0||-||1||0||-||-||-||-||-||-||0
+
−
|-
+
−
|FDC Data||&FB||Read/Write||-||-||-||-||-||0||-||1||0||-||-||-||-||-||-||1
+
−
|-
+
−
|FDC Motor||&FA||Write Only||-||-||-||-||-||0||-||0||0||-||-||-||-||-||-||-
+
−
|}
+
−
 
+
−
0 means the bit must be set to 0 for the hardware device to respond, 1 means the bit must be set to 1 for the hardware device to respond, - means this bit is ignored. r1 and r0 mean a bit used to define a register
+
  
 
== I/O Ports ==
 
== I/O Ports ==
  
−
{|{{Prettytable|width: 700px; font-size: 2em;}}
+
{| class="wikitable"
−
|'''I/O'''||'''Decoded as'''||'''Port'''||'''Read'''||'''Write'''
+
!I/O
 +
!Decoded as
 +
!Port
 +
!Read
 +
!Write
 
|-
 
|-
 
|#7FXX||%01xxxxxx xxxxxxxx||[[Gate Array]]||-||Write
 
|#7FXX||%01xxxxxx xxxxxxxx||[[Gate Array]]||-||Write
Line 97: Line 65:
  
 
* The eight [[Amstrad Serial Interface]] ports are pre-defined as shown above in the AMSDOS ROM. However, neither the CPC 664/6128/Plus nor DDI-1 do actually contain the corresponding RS232 hardware.
 
* The eight [[Amstrad Serial Interface]] ports are pre-defined as shown above in the AMSDOS ROM. However, neither the CPC 664/6128/Plus nor DDI-1 do actually contain the corresponding RS232 hardware.
 +
 +
* Bit14 of the PAL selection address must be at 1 on CPCs equipped with CRTCs 0/1/2. It can be at 0 or 1 on CRTCs 3/4. For compatibility reasons, it is strongly advised to always set bit14 to 1 to select PAL.
 +
 +
* 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.
 +
 +
<br>
  
 
== Memory Mapped I/O Ports ==
 
== Memory Mapped I/O Ports ==
  
−
{|{{Prettytable|width: 700px; font-size: 2em;}}
+
{| class="wikitable"
−
|'''Mem'''||'''Decoded as'''||'''Port'''||'''Read'''||'''Write'''
+
!Mem
 +
!Decoded as
 +
!Port
 +
!Read
 +
!Write
 
|-
 
|-
−
|#4000-7FFF||%01xxxxxx xxxxxxxx||[[ASIC]] - CPC+/GX4000 registers|| Read || Write
+
|#4000-7FFF||%01xxxxxx xxxxxxxx||ASIC - CPC+/GX4000 registers|| Read || Write
 
|-
 
|-
 
|}
 
|}
 +
 +
See the [[ASIC]] page for details.
 +
 +
<br>
 +
 +
==Related pages==
 +
 +
*[[Arnold V specs]]
 +
*[[Arnold V Specs Revised]]
  
 
[[Category:Programming]] [[Category:CPC Internal Components]]
 
[[Category:Programming]] [[Category:CPC Internal Components]]

Latest revision as of 06:23, 4 September 2024

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 Complete I/O Port Summary.


I/O Ports

I/O Decoded as Port Read 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
#EFXX %xxx0xxxx xxxxxxxx Printer Port - Write
#F4XX %xxxx0x00 xxxxxxxx 8255 PPI Port A (PSG Data) Read Write
#F5XX %xxxx0x01 xxxxxxxx 8255 PPI Port B (Vsync,PrnBusy,Tape,etc.) Read -
#F6XX %xxxx0x10 xxxxxxxx 8255 PPI Port C (KeybRow,Tape,PSG Control) - Write
#F7XX %xxxx0x11 xxxxxxxx 8255 PPI Control-Register - Write
#F8FF N/A Peripheral Soft Reset (MC_BOOT_PROGRAM and MC_START_PROGRAM do OUT [F8FF],FF) - Write
#FA7E %xxxxx0x0 0xxxxxxx Floppy Motor Control (for 765 FDC) - Write
#FADC %xxxxx0x0 xx0xxx00 Amstrad Serial Interface Z80-SIO / DART port A Data Register Read Write
#FADD %xxxxx0x0 xx0xxx01 Amstrad Serial Interface Z80-SIO / DART port A Control Reg. Read Write
#FADE %xxxxx0x0 xx0xxx10 Amstrad Serial Interface Z80-SIO / DART port B Data Register Read Write
#FADF %xxxxx0x0 xx0xxx11 Amstrad Serial Interface Z80-SIO / DART port B Control Reg. Read Write
#FB7E %xxxxx0x1 0xxxxxx0 765 FDC (internal) Status Register Read -
#FB7F %xxxxx0x1 0xxxxxx1 765 FDC (internal) Data Register Read Write
#FBDC %xxxxx0x1 xx0xxx00 Amstrad Serial Interface 8253 Timer counter 0 Read Write
#FBDD %xxxxx0x1 xx0xxx01 Amstrad Serial Interface 8253 Timer counter 1 Read Write
#FBDE %xxxxx0x1 xx0xxx10 Amstrad Serial Interface 8253 Timer counter 2 Read Write
#FBDF %xxxxx0x1 xx0xxx11 Amstrad Serial Interface 8253 Timer Modus Select - Write
  • The three 765 FDC floppy ports are contained in CPC 664/6128/Plus and DDI-1 only.
  • The eight Amstrad Serial Interface ports are pre-defined as shown above in the AMSDOS ROM. However, neither the CPC 664/6128/Plus nor DDI-1 do actually contain the corresponding RS232 hardware.
  • Bit14 of the PAL selection address must be at 1 on CPCs equipped with CRTCs 0/1/2. It can be at 0 or 1 on CRTCs 3/4. For compatibility reasons, it is strongly advised to always set bit14 to 1 to select PAL.
  • 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.


Memory Mapped I/O Ports

Mem Decoded as Port Read Write
#4000-7FFF %01xxxxxx xxxxxxxx ASIC - CPC+/GX4000 registers Read Write

See the ASIC page for details.


Related pages

Retrieved from "https://gryzor.info/index.php?title=Default_I/O_Port_Summary&oldid=118414"