1 /*****************************************************************************/
5 /* Memory subsystem for the 6502 simulator */
9 /* (C) 2002-2012, Ullrich von Bassewitz */
10 /* Roemerstrasse 52 */
11 /* D-70794 Filderstadt */
12 /* EMail: uz@cc65.org */
15 /* This software is provided 'as-is', without any expressed or implied */
16 /* warranty. In no event will the authors be held liable for any damages */
17 /* arising from the use of this software. */
19 /* Permission is granted to anyone to use this software for any purpose, */
20 /* including commercial applications, and to alter it and redistribute it */
21 /* freely, subject to the following restrictions: */
23 /* 1. The origin of this software must not be misrepresented; you must not */
24 /* claim that you wrote the original software. If you use this software */
25 /* in a product, an acknowledgment in the product documentation would be */
26 /* appreciated but is not required. */
27 /* 2. Altered source versions must be plainly marked as such, and must not */
28 /* be misrepresented as being the original software. */
29 /* 3. This notice may not be removed or altered from any source */
32 /*****************************************************************************/
42 /*****************************************************************************/
44 /*****************************************************************************/
49 static unsigned char Mem[0x10000];
53 /*****************************************************************************/
55 /*****************************************************************************/
59 void MemWriteByte (unsigned Addr, unsigned char Val)
60 /* Write a byte to a memory location */
67 unsigned char MemReadByte (unsigned Addr)
68 /* Read a byte from a memory location */
75 unsigned MemReadWord (unsigned Addr)
76 /* Read a word from a memory location */
78 unsigned W = MemReadByte (Addr++);
79 return (W | (MemReadByte (Addr) << 8));
84 unsigned MemReadZPWord (unsigned char Addr)
85 /* Read a word from the zero page. This function differs from ReadMemW in that
86 ** the read will always be in the zero page, even in case of an address
90 unsigned W = MemReadByte (Addr++);
91 return (W | (MemReadByte (Addr) << 8));
97 /* Initialize the memory subsystem */
99 /* Fill momory with illegal opcode */
100 memset (Mem, 0xFF, sizeof (Mem));
102 /* Set RESET vector to 0x0200 */