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erc-c/include/apple2.h
Peter Evans 8d9b48912e Add memory injection to 6502; main memory in apple2
Note that memory _is_ now managed in apple2, and _not_ in mos6502.
2018-01-10 21:28:05 -06:00

190 lines
5.3 KiB
C

#ifndef _APPLE2_H_
#define _APPLE2_H_
#include "apple2.dd.h"
#include "mos6502.h"
#include "vm_bitfont.h"
#include "vm_screen.h"
/*
* This is the size of the bitmap font we use for the apple2
*/
#define APPLE2_SYSFONT_SIZE 21558
/*
* The reset vector is the address where the apple will consult to
* figure out where control should go after a reset. Think of this as
* something like a pointer to a main() function in C. That is: where's
* the main function? Let's ask the reset vector!
*/
#define APPLE2_RESET_VECTOR 0x03F2
/*
* This is the address of the validity-check byte, aka the power-up
* byte. The Apple II will use this to see if the reset vector is valid.
*/
#define APPLE2_POWERUP_BYTE 0x03F4
/*
* I'm not _exactly_ clear on where the applesoft interpreter lives in
* ROM, after spending possibly too-much time researching how this
* works. My guess is I'm missing something that's obvious to others.
* $E000 seems to be the original spot that Integer BASIC was contained,
* and I'm going to guess Applesoft BASIC is in the same spot. Here's
* hoping!
*/
#define APPLE2_APPLESOFT_MAIN 0xE000
enum video_modes {
VIDEO_40COL_TEXT,
VIDEO_LORES,
VIDEO_HIRES,
VIDEO_80COL_TEXT,
VIDEO_DOUBLE_LORES,
VIDEO_DOUBLE_HIRES,
};
enum color_modes {
COLOR_GREEN,
COLOR_AMBER,
COLOR_GRAY,
COLOR_FULL,
};
enum lores_colors {
LORES_BLACK,
LORES_MAGENTA,
LORES_DARKBLUE,
LORES_PURPLE,
LORES_DARKGREEN,
LORES_GRAY1,
LORES_MEDBLUE,
LORES_LIGHTBLUE,
LORES_BROWN,
LORES_ORANGE,
LORES_GRAY2,
LORES_PINK,
LORES_LIGHTGREEN,
LORES_YELLOW,
LORES_AQUAMARINE,
LORES_WHITE,
};
// Write-protect on/off.
// Read target = ROM or RAM.
// Write target = RAM.
// Set mode of $Dxxx hexapage bank1 or bank2 ram.
// 0 - 0=off 1=on
// 1 - 0=ROM 1=RAM
// 2 - 0=BANK1 1=BANK2
/*
* An Apple II has bank-switched memory beginning with $D000 extending
* through $FFFF. The enums below define bit flag names to determine
* what is accessible through those addresses.
*
* Note that it _is_ possible to write while reading ROM, but your
* writes will not go to ROM; they'll go to _RAM_. Any write to $E000 -
* $FFFF may only be sent to bank 1 RAM. Writes to $D000-$DFFF may
* either be sent to bank 1 RAM or bank 2 RAM based upon the RAM2 bit
* flag below.
*/
enum memory_mode {
MEMORY_ROM = 1, // on = read ROM; off = read RAM
MEMORY_WRITE = 2, // on = allow writes to RAM; off = disallow writes
MEMORY_RAM2 = 4, // on = use bank 2 for $D000-$DFFF; off = use bank 1
};
typedef struct {
/*
* The apple 2 hardware used an MOS-6502 processor.
*/
mos6502 *cpu;
/*
* This is the main memory bank of the computer. Conventionally, it
* contains not only the first contiguous 48k of RAM, but it also
* contains the last 12k of bank 1 RAM.
*/
vm_segment *main;
/*
* The Apple II used a system of bank-switched memory to enable
* software to address a separate block of ROM.
*/
vm_segment *rom;
/*
* Additionally, the Apple II had a standalone block of RAM (with no
* good name for it, really, hence the regrettably vague "ram2") so
* that you technically could use 16k of RAM from a set of 12k
* addresses. The extra 4k lives a lonely life in the garage
* apartment.
*/
vm_segment *ram2;
/*
* The Apple II may have an auxiliary RAM bank; this was possible by
* installing a card there. If you had the 80-column text card (and
* you likely did), then you got an extra kilobyte of RAM to work
* with; it was either used for the extra columns or you could take
* advantage of it for extra storage otherwise.
*/
vm_segment *aux;
/*
* The screen wherein we shall render all of our graphics.
*/
vm_screen *screen;
/*
* This is the system font (the only font the Apple II knows about,
* really); anywhere we render text, we have to use this font.
*/
vm_bitfont *sysfont;
/*
* This is the mode in which we must interpret graphics. This will
* tell us not only if we're in lo- or hi-res, but also if we are in
* single or double view mode.
*/
int video_mode;
/*
* This is the color mode we want to emulate. You can have a few
* different styles of monochromatic displays: green, amber, and
* light gray on black; you can also emulate a full color display,
* in which text mode tends to look like light gray.
*/
int color_mode;
/*
* This describes the behavior of our bank-switching scheme. We need
* our read/write mappers to know where writes into the
* bank-switched area of memory should target.
*/
vm_8bit bank_switch;
/*
* Our two disk drives.
*/
apple2dd *drive1;
apple2dd *drive2;
} apple2;
extern apple2 *apple2_create(int, int);
extern bool apple2_is_double_video(apple2 *);
extern int apple2_boot(apple2 *);
extern void apple2_clear_strobe(apple2 *);
extern void apple2_free(apple2 *);
extern void apple2_press_key(apple2 *, vm_8bit);
extern void apple2_release_key(apple2 *);
extern void apple2_reset(apple2 *);
extern void apple2_run_loop(apple2 *);
extern void apple2_set_color(apple2 *, int);
extern void apple2_set_bank_switch(apple2 *, vm_8bit);
extern void apple2_set_video(apple2 *, int);
#endif