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erc-c/include/apple2.mem.h
2018-01-16 23:49:14 -06:00

76 lines
2.2 KiB
C

#ifndef _APPLE2_MEM_H_
#define _APPLE2_MEM_H_
#include "apple2.h"
#include "vm_segment.h"
/*
* The MOS 6502 expects 64k of addressable space, but the Apple II
* technically has 68k of memory in each bank. (Along with having both a
* main and an auxiliary memory bank, with identical address schemes.)
* This is handled through bank-switching; the additional memory (which
* is accessible through $D000 - $DFFF) is actually stored in the
* 64k-68k block at the end.
*/
#define APPLE2_MEMORY_SIZE 0x11000
/*
* Given a slot number (1-7), this will return the memory page address
* for the site of the ROM that is associated for the peripheral that
* would be connected there.
*/
#define APPLE2_PERIPHERAL_SLOT(n) \
(0xC000 + (n << 8))
/*
* This is the total size of the ROM we hold devoted to peripherals. It
* is meant to be mapped directly to the entire $C000..$CFFF space; it's
* zero-padded for the $C0 page, and is also zero-padded in $C8..$CF;
* the latter being reserved for expansion peripheral ROM usage, and the
* former for the I/O soft switches that the Apple II has.
*/
#define APPLE2_PERIPHERAL_SIZE 0x1000
/*
* Peripheral ROM can only occupy a single page in memory.
*/
#define APPLE2_PERIPHERAL_PAGE 0x100
/*
* System ROM requires a full 16k; part of it is copied into several
* pages beginning at $C800, and much more go into $D000 - $FFFF.
*/
#define APPLE2_SYSROM_SIZE 0x4000
/*
* The size of our block of ROM is 20k; 16k for internal ROM, 4k to
* contain all of the peripheral ROM above.
*/
#define APPLE2_ROM_SIZE 0x5000
/*
* At the highest point (with the IIe extended 80 column text card), you
* could have a whole other 64k of data in auxiliary memory. (Of which
* only 1k was needed for 80 columns!)
*/
#define APPLE2_AUX_SIZE 0x10000
/*
* This is the base address for system / internal ROM.
*/
#define APPLE2_SYSROM_OFFSET 0xC000
/*
* This defines the base address for bank-switchable memory
*/
#define APPLE2_BANK_OFFSET 0xD000
extern SEGMENT_READER(apple2_mem_zp_read);
extern SEGMENT_WRITER(apple2_mem_zp_write);
extern int apple2_mem_init_sys_rom(apple2 *);
extern void apple2_mem_map(apple2 *, vm_segment *);
extern SEGMENT_READER(apple2_mem_switch_read);
extern SEGMENT_WRITER(apple2_mem_switch_write);
#endif