mirror of
https://github.com/pevans/erc-c.git
synced 2024-11-27 20:51:17 +00:00
c953616a71
There is one failing test, which I expect to fail at this point; that's because we need to write a read/write map function for the stack and zero page so that they use aux memory when BANK_ALTZP is on, and main memory when not.
270 lines
8.0 KiB
C
270 lines
8.0 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 {
|
|
/*
|
|
* By default, memory accesses go to main memory in _all_ cases.
|
|
* Auxiliary memory is not used in any capacity.
|
|
*/
|
|
MEMORY_DEFAULT = 0x0,
|
|
|
|
/*
|
|
* When this is on, the core 48k (non bank-switchable) of memory
|
|
* will be read from auxiliary memory. When off, it will be read
|
|
* from main memory.
|
|
*/
|
|
MEMORY_READ_AUX = 0x1,
|
|
|
|
/*
|
|
* When on, writes to the core 48k of memory will go to aux; when
|
|
* off, they go to main.
|
|
*/
|
|
MEMORY_WRITE_AUX = 0x2,
|
|
|
|
/*
|
|
* This bit is what the tech reference calls an "enabling" switch,
|
|
* for PAGE2 and HIRES below. If this bit is not on, then those two
|
|
* other bits don't do anything, and all aux memory access is
|
|
* governed by WRITE_AUX and READ_AUX above.
|
|
*/
|
|
MEMORY_80STORE = 0x4,
|
|
|
|
/*
|
|
* When 80STORE is on, PAGE2 will allow you to access auxiliary
|
|
* memory for the display page. The range depends on HIRES below.
|
|
* When PAGE2 is on and HIRES is off, then PAGE2 causes accesses to
|
|
* $0400..$07FF to always go to auxiliary memory (read or writes).
|
|
* When both PAGE2 and HIRES are on, then $2000..$3FFF also go to
|
|
* aux memory. When 80STORE is off, then these two bits are ignored.
|
|
*/
|
|
MEMORY_PAGE2 = 0x8,
|
|
MEMORY_HIRES = 0x10,
|
|
};
|
|
|
|
enum bank_switch {
|
|
/*
|
|
* In nominal bank-switch mode, reads in the bank-switchable address
|
|
* space go to ROM; writes to RAM are protected; and bank2 memory is
|
|
* used.
|
|
*/
|
|
BANK_DEFAULT = 0x0,
|
|
|
|
/*
|
|
* When on, this reads from RAM in bank-switched memory. When off,
|
|
* it reads from ROM.
|
|
*/
|
|
BANK_RAM = 0x1,
|
|
|
|
/*
|
|
* When on, we will write to RAM. When off, we will write-protect
|
|
* RAM in bank-switched memory. NOTE: we can never write to ROM--or
|
|
* else it wouldn't be ROM! So if you have BANK_RAM off, but
|
|
* BANK_WRITE on, then writes do not fail, but they do go to RAM.
|
|
*/
|
|
BANK_WRITE = 0x2,
|
|
|
|
/*
|
|
* When this is on, we will use bank 2 RAM when accessing the $Dnnn
|
|
* range; otherwise, we use bank 1 (as you might guess).
|
|
*/
|
|
BANK_RAM2 = 0x4,
|
|
|
|
/*
|
|
* This is a weird little bit. When BANK_ALTZP is on, the zero page
|
|
* and stack are accessed from auxiliary memory rather than main
|
|
* memory. Those two pages of memory, however, are _copied_ from one
|
|
* to the other, so data should remain consistent.
|
|
*
|
|
* That's not the weird part. That part makes sense given the name
|
|
* (which isn't my name, but is the name used in the IIe technical
|
|
* reference). The part that isn't so obvious is that
|
|
* bank-switchable RAM will _also_ be accessed from auxiliary
|
|
* memory, not main memory. Note that aux memory has its own second
|
|
* bank of RAM, the way that main memory does, so BANK_RAM2 works
|
|
* the way you think, but it works with the aux RAM2. No data is
|
|
* copied between main and aux's bank-switched memory, unlike the
|
|
* way zero page and the stack are handled.
|
|
*/
|
|
BANK_ALTZP = 0x8,
|
|
};
|
|
|
|
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;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
/*
|
|
* Beside bank-switching, we also need to keep track of memory
|
|
* modes; these pertain mostly to reading from main or auxiliary
|
|
* memory.
|
|
*/
|
|
vm_8bit memory_mode;
|
|
|
|
/*
|
|
* 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_bank_switch(apple2 *, vm_8bit);
|
|
extern void apple2_set_color(apple2 *, int);
|
|
extern void apple2_set_memory_mode(apple2 *, vm_8bit);
|
|
extern void apple2_set_video(apple2 *, int);
|
|
|
|
#endif
|