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source: trunk/I8255.pas

Last change on this file was 8, checked in by chronos, 3 weeks ago
Modified: Implemented more instructions. Added: Hardware emulation of 8255 and 8253 chips.
File size: 758 bytes

Line
1	unit I8255;
2
3	interface
4
5	uses
6	Classes, SysUtils;
7
8	type
9
10	{ T8255 }
11
12	T8255 = class
13	PortA: Byte;
14	PortB: Byte;
15	PortC: Byte;
16	Active: Boolean;
17	ControlWord: Byte;
18	procedure Write(Address: Word; Data: Byte);
19	function Read(Address: Word): Byte;
20	end;
21
22
23	implementation
24
25	{ T8255 }
26
27	procedure T8255.Write(Address: Word; Data: Byte);
28	begin
29	case Address of
30	0: PortA := Data;
31	1: PortB := Data;
32	2: PortC := Data;
33	3: begin
34	ControlWord := Data;
35	Active := (ControlWord and $80) > 0;
36	end;
37	end;
38	end;
39
40	function T8255.Read(Address: Word): Byte;
41	begin
42	case Address of
43	0: Result := PortA;
44	1: Result := PortB;
45	2: Result := PortC;
46	3: begin
47	Result := ControlWord;
48	end;
49	end;
50	end;
51
52	end.
53

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