8255 - Revision history

Phi2x: /* PPI Port B */

2025-03-30T12:40:50Z

‎PPI Port B

Phi2x: /* PPI Port C */

2025-03-30T12:40:40Z

‎PPI Port C

Phi2x: /* The 8255 in the CPC */

2025-03-30T12:34:05Z

‎The 8255 in the CPC

Phi2x: /* The 8255 in the CPC */

2025-03-30T12:33:21Z

‎The 8255 in the CPC

Phi2x: /* The 8255 in the CPC */

2025-03-30T12:32:46Z

‎The 8255 in the CPC

Phi2x: /* PPI Port C */

2025-03-30T12:31:54Z

‎PPI Port C

Phi2x: /* PPI Port B */

2025-03-30T12:30:26Z

‎PPI Port B

Phi2x: /* PPI Port C */

2025-03-30T12:28:41Z

‎PPI Port C

Phi2x: /* PPI Port B */

2025-03-30T12:18:39Z

‎PPI Port B

Deprecated: The each() function is deprecated. This message will be suppressed on further calls in /mnt/cpcwiki-httpdocs/includes/diff/DairikiDiff.php on line 434

Phi2x: /* PPI Port C */

2025-03-30T06:21:39Z

‎PPI Port C

@@ Line 92: / Line 92: @@
 |-
 |3||LK3|| rowspan="3" |Distributor ID. Usually set to 4=[[Awa]], 5=[[Schneider]], or 7=[[Amstrad]]
-see [[LK-selectable Brand Names]] for details
+See [[LK-selectable Brand Names]] for details
 ||Purpose unknown (set to "1")
 |-

@@ Line 182: / Line 182: @@
 |-
 |3||rowspan=4|Keyboard line||rowspan=4|Select keyboard line to be scanned (0-15)
 |-
 |2

@@ Line 16: / Line 16: @@
 The [[8255 PPI chip]] is a general purpose input/output IC. This document will describe its role in the Amstrad CPC, CPC+ and KC compact systems. To understand its full functions please read the datasheet.
-In these systems it is connected to the [[PSG|AY-3-8912 Programmable Sound Generator (PSG)]], keyboard, cassette recorder, the VSYNC of the 6845 CRTC and the "busy" signal from the parallel port.
+In these systems it is connected to the [[PSG|AY-3-8912 Programmable Sound Generator (PSG)]], keyboard, cassette recorder, the VSYNC of the [[CRTC|6845 CRTC]] and the "busy" signal from the parallel port.
 The PPI is selected when A11 of the I/O port address is set to "0", A9 and A8 then define the PPI function access (as shown below), A15-A12 and A10 should be "1" (to prevent conflicts with other hardware), A7-A0 are don't care. So, resulting Port addresses are:

@@ Line 16: / Line 16: @@
 The [[8255 PPI chip]] is a general purpose input/output IC. This document will describe its role in the Amstrad CPC, CPC+ and KC compact systems. To understand its full functions please read the datasheet.
-In these systems it is connected to the AY-3-8912 [[PSG|Programmable Sound Generator (PSG)]], keyboard, cassette recorder, the VSYNC of the 6845 CRTC and the "busy" signal from the parallel port.
+In these systems it is connected to the [[PSG|AY-3-8912 Programmable Sound Generator (PSG)]], keyboard, cassette recorder, the VSYNC of the 6845 CRTC and the "busy" signal from the parallel port.
 The PPI is selected when A11 of the I/O port address is set to "0", A9 and A8 then define the PPI function access (as shown below), A15-A12 and A10 should be "1" (to prevent conflicts with other hardware), A7-A0 are don't care. So, resulting Port addresses are:

@@ Line 16: / Line 16: @@
 The [[8255 PPI chip]] is a general purpose input/output IC. This document will describe its role in the Amstrad CPC, CPC+ and KC compact systems. To understand its full functions please read the datasheet.
-In these systems it is connected to the AY-3-8912 Programmable Sound Generator (PSG), keyboard, cassette recorder, the VSYNC of the 6845 CRTC and the "busy" signal from the parallel port.
+In these systems it is connected to the AY-3-8912 [[PSG|Programmable Sound Generator (PSG)]], keyboard, cassette recorder, the VSYNC of the 6845 CRTC and the "busy" signal from the parallel port.
 The PPI is selected when A11 of the I/O port address is set to "0", A9 and A8 then define the PPI function access (as shown below), A15-A12 and A10 should be "1" (to prevent conflicts with other hardware), A7-A0 are don't care. So, resulting Port addresses are:

@@ Line 192: / Line 192: @@
 {| class="wikitable"
-|+ PSG function selection
+|+ [[PSG]] function selection
 !Bit 7
 !Bit 6

@@ Line 81: / Line 81: @@
 !Description
 !Usage in CPC
-!Usage in KC Compact
+!Usage in [[KC Compact]]
 |-
 |7||CAS.IN||Cassette data input||Same as on CPC

@@ Line 173: / Line 173: @@
 !Usage
 |-
-|7||PSG BDIR||PSG function selection
+|7||PSG BDIR (Bus DIRection)||rowspan=2|PSG function selection
 |-
-|6||PSG BC1||
+|6||PSG BC1 (Bus Control 1)
 |-
 |5||Cassette Write data||Cassette Out (sometimes also used as Printer Bit7, see [[8bit Printer Ports]])

@@ Line 91: / Line 91: @@
 |4||LK4||Screen Refresh Rate ("1"=50Hz, "0"=60Hz)||Set to "1"=50Hz (but ignored by the KC BIOS, which always uses 50Hz even if LK4 is changed)
 |-
-|3||LK3|| rowspan="3" |3bit Distributor ID. Usually set to 4=[[Awa]], 5=[[Schneider]], or 7=[[Amstrad]], see [[LK-selectable Brand Names]] for details.||Purpose unknown (set to "1")
+|3||LK3|| rowspan="3" |Distributor ID. Usually set to 4=[[Awa]], 5=[[Schneider]], or 7=[[Amstrad]]
 |-
 |2||LK2||Purpose unknown (set to "0")
@@ Line 99: / Line 101: @@
 |0||[[CRTC]] VSYNC||Vertical Sync ("1"=VSYNC active, "0"=VSYNC inactive)||Same as on CPC
 |-
 |}