86Box/src/machine/m_pcjr.c

/*
 * 86Box	A hypervisor and IBM PC system emulator that specializes in
 *		running old operating systems and software designed for IBM
 *		PC systems and compatibles from 1981 through fairly recent
 *		system designs based on the PCI bus.
 *
 *		This file is part of the 86Box distribution.
 *
 *		Emulation of the IBM PCjr.
 *
 *
 *
 * Authors:	Sarah Walker, <http://pcem-emulator.co.uk/>
 *		Miran Grca, <mgrca8@gmail.com>
 *		Fred N. van Kempen, <decwiz@yahoo.com>
 *
 *		Copyright 2008-2019 Sarah Walker.
 *		Copyright 2016-2019 Miran Grca.
 *		Copyright 2017-2019 Fred N. van Kempen.
 */
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#include <wchar.h>
#define HAVE_STDARG_H
#include <86box/86box.h>
#include "cpu.h"
#include <86box/timer.h>
#include <86box/device.h>
#include <86box/cassette.h>
#include <86box/io.h>
#include <86box/nmi.h>
#include <86box/pic.h>
#include <86box/pit.h>
#include <86box/mem.h>
#include <86box/device.h>
#include <86box/serial.h>
#include <86box/keyboard.h>
#include <86box/rom.h>
#include <86box/fdd.h>
#include <86box/fdc.h>
#include <86box/sound.h>
#include <86box/snd_speaker.h>
#include <86box/snd_sn76489.h>
#include <86box/video.h>
#include <86box/vid_cga_comp.h>
#include <86box/machine.h>

#define PCJR_RGB       0
#define PCJR_COMPOSITE 1

#define STAT_PARITY    0x80
#define STAT_RTIMEOUT  0x40
#define STAT_TTIMEOUT  0x20
#define STAT_LOCK      0x10
#define STAT_CD        0x08
#define STAT_SYSFLAG   0x04
#define STAT_IFULL     0x02
#define STAT_OFULL     0x01

typedef struct {
    /* Video Controller stuff. */
    mem_mapping_t mapping;
    uint8_t       crtc[32];
    int           crtcreg;
    int           array_index;
    uint8_t       array[32];
    int           array_ff;
    int           memctrl;
    uint8_t       stat;
    int           addr_mode;
    uint8_t      *vram,
        *b8000;
    int        linepos, displine;
    int        sc, vc;
    int        dispon;
    int        con, coff, cursoron, blink;
    int        vsynctime;
    int        fullchange;
    int        vadj;
    uint16_t   ma, maback;
    uint64_t   dispontime, dispofftime;
    pc_timer_t timer;
    int        firstline, lastline;
    int        composite;

    /* Keyboard Controller stuff. */
    int        latched;
    int        data;
    int        serial_data[44];
    int        serial_pos;
    uint8_t    pa;
    uint8_t    pb;
    pc_timer_t send_delay_timer;
} pcjr_t;

static video_timings_t timing_dram = { VIDEO_BUS, 0, 0, 0, 0, 0, 0 }; /*No additional waitstates*/

static uint8_t crtcmask[32] = {
    0xff, 0xff, 0xff, 0xff, 0x7f, 0x1f, 0x7f, 0x7f,
    0xf3, 0x1f, 0x7f, 0x1f, 0x3f, 0xff, 0x3f, 0xff,
    0xff, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
static uint8_t key_queue[16];
static int     key_queue_start = 0,
           key_queue_end       = 0;

static void
recalc_address(pcjr_t *pcjr)
{
    if ((pcjr->memctrl & 0xc0) == 0xc0) {
        pcjr->vram  = &ram[(pcjr->memctrl & 0x06) << 14];
        pcjr->b8000 = &ram[(pcjr->memctrl & 0x30) << 11];
    } else {
        pcjr->vram  = &ram[(pcjr->memctrl & 0x07) << 14];
        pcjr->b8000 = &ram[(pcjr->memctrl & 0x38) << 11];
    }
}

static void
recalc_timings(pcjr_t *pcjr)
{
    double _dispontime, _dispofftime, disptime;

    if (pcjr->array[0] & 1) {
        disptime    = pcjr->crtc[0] + 1;
        _dispontime = pcjr->crtc[1];
    } else {
        disptime    = (pcjr->crtc[0] + 1) << 1;
        _dispontime = pcjr->crtc[1] << 1;
    }

    _dispofftime = disptime - _dispontime;
    _dispontime *= CGACONST;
    _dispofftime *= CGACONST;
    pcjr->dispontime  = (uint64_t) (_dispontime);
    pcjr->dispofftime = (uint64_t) (_dispofftime);
}

static void
vid_out(uint16_t addr, uint8_t val, void *p)
{
    pcjr_t *pcjr = (pcjr_t *) p;
    uint8_t old;

    switch (addr) {
        case 0x3d4:
            pcjr->crtcreg = val & 0x1f;
            return;

        case 0x3d5:
            old                       = pcjr->crtc[pcjr->crtcreg];
            pcjr->crtc[pcjr->crtcreg] = val & crtcmask[pcjr->crtcreg];
            if (old != val) {
                if (pcjr->crtcreg < 0xe || pcjr->crtcreg > 0x10) {
                    pcjr->fullchange = changeframecount;
                    recalc_timings(pcjr);
                }
            }
            return;

        case 0x3da:
            if (!pcjr->array_ff)
                pcjr->array_index = val & 0x1f;
            else {
                if (pcjr->array_index & 0x10)
                    val &= 0x0f;
                pcjr->array[pcjr->array_index & 0x1f] = val;
                if (!(pcjr->array_index & 0x1f))
                    update_cga16_color(val);
            }
            pcjr->array_ff = !pcjr->array_ff;
            break;

        case 0x3df:
            pcjr->memctrl   = val;
            pcjr->addr_mode = val >> 6;
            recalc_address(pcjr);
            break;
    }
}

static uint8_t
vid_in(uint16_t addr, void *p)
{
    pcjr_t *pcjr = (pcjr_t *) p;
    uint8_t ret  = 0xff;

    switch (addr) {
        case 0x3d4:
            ret = pcjr->crtcreg;
            break;

        case 0x3d5:
            ret = pcjr->crtc[pcjr->crtcreg];
            break;

        case 0x3da:
            pcjr->array_ff = 0;
            pcjr->stat ^= 0x10;
            ret = pcjr->stat;
            break;
    }

    return (ret);
}

static void
vid_write(uint32_t addr, uint8_t val, void *p)
{
    pcjr_t *pcjr = (pcjr_t *) p;

    if (pcjr->memctrl == -1)
        return;

    pcjr->b8000[addr & 0x3fff] = val;
}

static uint8_t
vid_read(uint32_t addr, void *p)
{
    pcjr_t *pcjr = (pcjr_t *) p;

    if (pcjr->memctrl == -1)
        return (0xff);

    return (pcjr->b8000[addr & 0x3fff]);
}

static void
vid_poll(void *p)
{
    pcjr_t  *pcjr = (pcjr_t *) p;
    uint16_t ca   = (pcjr->crtc[15] | (pcjr->crtc[14] << 8)) & 0x3fff;
    int      drawcursor;
    int      x, c, xs_temp, ys_temp;
    int      oldvc;
    uint8_t  chr, attr;
    uint16_t dat;
    int      cols[4];
    int      oldsc;

    if (!pcjr->linepos) {
        timer_advance_u64(&pcjr->timer, pcjr->dispofftime);
        pcjr->stat &= ~1;
        pcjr->linepos = 1;
        oldsc         = pcjr->sc;
        if ((pcjr->crtc[8] & 3) == 3)
            pcjr->sc = (pcjr->sc << 1) & 7;
        if (pcjr->dispon) {
            uint16_t offset = 0;
            uint16_t mask   = 0x1fff;

            if (pcjr->displine < pcjr->firstline) {
                pcjr->firstline = pcjr->displine;
                video_wait_for_buffer();
            }
            pcjr->lastline = pcjr->displine;
            cols[0]        = (pcjr->array[2] & 0xf) + 16;
            for (c = 0; c < 8; c++) {
                ((uint32_t *) buffer32->line[pcjr->displine])[c] = cols[0];
                if (pcjr->array[0] & 1) {
                    buffer32->line[(pcjr->displine << 1)][c + (pcjr->crtc[1] << 3) + 8] = buffer32->line[(pcjr->displine << 1) + 1][c + (pcjr->crtc[1] << 3) + 8] = cols[0];
                } else {
                    buffer32->line[(pcjr->displine << 1)][c + (pcjr->crtc[1] << 4) + 8] = buffer32->line[(pcjr->displine << 1) + 1][c + (pcjr->crtc[1] << 4) + 8] = cols[0];
                }
            }

            switch (pcjr->addr_mode) {
                case 0: /*Alpha*/
                    offset = 0;
                    mask   = 0x3fff;
                    break;
                case 1: /*Low resolution graphics*/
                    offset = (pcjr->sc & 1) * 0x2000;
                    break;
                case 3: /*High resolution graphics*/
                    offset = (pcjr->sc & 3) * 0x2000;
                    break;
            }
            switch ((pcjr->array[0] & 0x13) | ((pcjr->array[3] & 0x08) << 5)) {
                case 0x13: /*320x200x16*/
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        dat = (pcjr->vram[((pcjr->ma << 1) & mask) + offset] << 8) | pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        pcjr->ma++;
                        buffer32->line[(pcjr->displine << 1)][(x << 3) + 8] = buffer32->line[(pcjr->displine << 1)][(x << 3) + 9] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 9] = pcjr->array[((dat >> 12) & pcjr->array[1]) + 16] + 16;
                        buffer32->line[(pcjr->displine << 1)][(x << 3) + 10] = buffer32->line[(pcjr->displine << 1)][(x << 3) + 11] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 10] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 11] = pcjr->array[((dat >> 8) & pcjr->array[1]) + 16] + 16;
                        buffer32->line[(pcjr->displine << 1)][(x << 3) + 12] = buffer32->line[(pcjr->displine << 1)][(x << 3) + 13] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 12] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 13] = pcjr->array[((dat >> 4) & pcjr->array[1]) + 16] + 16;
                        buffer32->line[(pcjr->displine << 1)][(x << 3) + 14] = buffer32->line[(pcjr->displine << 1)][(x << 3) + 15] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 14] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 15] = pcjr->array[(dat & pcjr->array[1]) + 16] + 16;
                    }
                    break;
                case 0x12: /*160x200x16*/
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        dat = (pcjr->vram[((pcjr->ma << 1) & mask) + offset] << 8) | pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        pcjr->ma++;
                        buffer32->line[(pcjr->displine << 1)][(x << 4) + 8] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 9] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 10] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 11] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 9] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 10] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 11] = pcjr->array[((dat >> 12) & pcjr->array[1]) + 16] + 16;
                        buffer32->line[(pcjr->displine << 1)][(x << 4) + 12] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 13] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 14] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 15] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 12] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 13] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 14] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 15] = pcjr->array[((dat >> 8) & pcjr->array[1]) + 16] + 16;
                        buffer32->line[(pcjr->displine << 1)][(x << 4) + 16] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 17] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 18] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 19] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 16] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 17] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 18] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 19] = pcjr->array[((dat >> 4) & pcjr->array[1]) + 16] + 16;
                        buffer32->line[(pcjr->displine << 1)][(x << 4) + 20] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 21] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 22] = buffer32->line[(pcjr->displine << 1)][(x << 4) + 23] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 20] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 21] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 22] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + 23] = pcjr->array[(dat & pcjr->array[1]) + 16] + 16;
                    }
                    break;
                case 0x03: /*640x200x4*/
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        dat = (pcjr->vram[((pcjr->ma << 1) & mask) + offset] << 8) | pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        pcjr->ma++;
                        for (c = 0; c < 8; c++) {
                            chr = (dat >> 7) & 1;
                            chr |= ((dat >> 14) & 2);
                            buffer32->line[(pcjr->displine << 1)][(x << 3) + 8 + c] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + 8 + c] = pcjr->array[(chr & pcjr->array[1]) + 16] + 16;
                            dat <<= 1;
                        }
                    }
                    break;
                case 0x01: /*80 column text*/
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        chr        = pcjr->vram[((pcjr->ma << 1) & mask) + offset];
                        attr       = pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        drawcursor = ((pcjr->ma == ca) && pcjr->con && pcjr->cursoron);
                        if (pcjr->array[3] & 4) {
                            cols[1] = pcjr->array[((attr & 15) & pcjr->array[1]) + 16] + 16;
                            cols[0] = pcjr->array[(((attr >> 4) & 7) & pcjr->array[1]) + 16] + 16;
                            if ((pcjr->blink & 16) && (attr & 0x80) && !drawcursor)
                                cols[1] = cols[0];
                        } else {
                            cols[1] = pcjr->array[((attr & 15) & pcjr->array[1]) + 16] + 16;
                            cols[0] = pcjr->array[((attr >> 4) & pcjr->array[1]) + 16] + 16;
                        }
                        if (pcjr->sc & 8) {
                            for (c = 0; c < 8; c++) {
                                buffer32->line[(pcjr->displine << 1)][(x << 3) + c + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + c + 8] = cols[0];
                            }
                        } else {
                            for (c = 0; c < 8; c++) {
                                buffer32->line[(pcjr->displine << 1)][(x << 3) + c + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + c + 8] = cols[(fontdat[chr][pcjr->sc & 7] & (1 << (c ^ 7))) ? 1 : 0];
                            }
                        }
                        if (drawcursor) {
                            for (c = 0; c < 8; c++) {
                                buffer32->line[(pcjr->displine << 1)][(x << 3) + c + 8] ^= 15;
                                buffer32->line[(pcjr->displine << 1) + 1][(x << 3) + c + 8] ^= 15;
                            }
                        }
                        pcjr->ma++;
                    }
                    break;
                case 0x00: /*40 column text*/
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        chr        = pcjr->vram[((pcjr->ma << 1) & mask) + offset];
                        attr       = pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        drawcursor = ((pcjr->ma == ca) && pcjr->con && pcjr->cursoron);
                        if (pcjr->array[3] & 4) {
                            cols[1] = pcjr->array[((attr & 15) & pcjr->array[1]) + 16] + 16;
                            cols[0] = pcjr->array[(((attr >> 4) & 7) & pcjr->array[1]) + 16] + 16;
                            if ((pcjr->blink & 16) && (attr & 0x80) && !drawcursor)
                                cols[1] = cols[0];
                        } else {
                            cols[1] = pcjr->array[((attr & 15) & pcjr->array[1]) + 16] + 16;
                            cols[0] = pcjr->array[((attr >> 4) & pcjr->array[1]) + 16] + 16;
                        }
                        pcjr->ma++;
                        if (pcjr->sc & 8) {
                            for (c = 0; c < 8; c++) {
                                buffer32->line[(pcjr->displine << 1)][(x << 4) + (c << 1) + 8] = buffer32->line[(pcjr->displine << 1)][(x << 4) + (c << 1) + 1 + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + (c << 1) + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + (c << 1) + 1 + 8] = cols[0];
                            }
                        } else {
                            for (c = 0; c < 8; c++) {
                                buffer32->line[(pcjr->displine << 1)][(x << 4) + (c << 1) + 8] = buffer32->line[(pcjr->displine << 1)][(x << 4) + (c << 1) + 1 + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + (c << 1) + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + (c << 1) + 1 + 8] = cols[(fontdat[chr][pcjr->sc & 7] & (1 << (c ^ 7))) ? 1 : 0];
                            }
                        }
                        if (drawcursor) {
                            for (c = 0; c < 16; c++) {
                                buffer32->line[(pcjr->displine << 1)][(x << 4) + c + 8] ^= 15;
                                buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + c + 8] ^= 15;
                            }
                        }
                    }
                    break;
                case 0x02: /*320x200x4*/
                    cols[0] = pcjr->array[0 + 16] + 16;
                    cols[1] = pcjr->array[1 + 16] + 16;
                    cols[2] = pcjr->array[2 + 16] + 16;
                    cols[3] = pcjr->array[3 + 16] + 16;
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        dat = (pcjr->vram[((pcjr->ma << 1) & mask) + offset] << 8) | pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        pcjr->ma++;
                        for (c = 0; c < 8; c++) {
                            buffer32->line[(pcjr->displine << 1)][(x << 4) + (c << 1) + 8] = buffer32->line[(pcjr->displine << 1)][(x << 4) + (c << 1) + 1 + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + (c << 1) + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + (c << 1) + 1 + 8] = cols[dat >> 14];
                            dat <<= 2;
                        }
                    }
                    break;
                case 0x102: /*640x200x2*/
                    cols[0] = pcjr->array[0 + 16] + 16;
                    cols[1] = pcjr->array[1 + 16] + 16;
                    for (x = 0; x < pcjr->crtc[1]; x++) {
                        dat = (pcjr->vram[((pcjr->ma << 1) & mask) + offset] << 8) | pcjr->vram[((pcjr->ma << 1) & mask) + offset + 1];
                        pcjr->ma++;
                        for (c = 0; c < 16; c++) {
                            buffer32->line[(pcjr->displine << 1)][(x << 4) + c + 8] = buffer32->line[(pcjr->displine << 1) + 1][(x << 4) + c + 8] = cols[dat >> 15];
                            dat <<= 1;
                        }
                    }
                    break;
            }
        } else {
            if (pcjr->array[3] & 4) {
                if (pcjr->array[0] & 1) {
                    hline(buffer32, 0, (pcjr->displine << 1), (pcjr->crtc[1] << 3) + 16, (pcjr->array[2] & 0xf) + 16);
                    hline(buffer32, 0, (pcjr->displine << 1) + 1, (pcjr->crtc[1] << 3) + 16, (pcjr->array[2] & 0xf) + 16);
                } else {
                    hline(buffer32, 0, (pcjr->displine << 1), (pcjr->crtc[1] << 4) + 16, (pcjr->array[2] & 0xf) + 16);
                    hline(buffer32, 0, (pcjr->displine << 1) + 1, (pcjr->crtc[1] << 4) + 16, (pcjr->array[2] & 0xf) + 16);
                }
            } else {
                cols[0] = pcjr->array[0 + 16] + 16;
                if (pcjr->array[0] & 1) {
                    hline(buffer32, 0, (pcjr->displine << 1), (pcjr->crtc[1] << 3) + 16, cols[0]);
                    hline(buffer32, 0, (pcjr->displine << 1) + 1, (pcjr->crtc[1] << 3) + 16, cols[0]);
                } else {
                    hline(buffer32, 0, (pcjr->displine << 1), (pcjr->crtc[1] << 4) + 16, cols[0]);
                    hline(buffer32, 0, (pcjr->displine << 1) + 1, (pcjr->crtc[1] << 4) + 16, cols[0]);
                }
            }
        }
        if (pcjr->array[0] & 1)
            x = (pcjr->crtc[1] << 3) + 16;
        else
            x = (pcjr->crtc[1] << 4) + 16;
        if (pcjr->composite) {
            Composite_Process(pcjr->array[0], 0, x >> 2, buffer32->line[(pcjr->displine << 1)]);
            Composite_Process(pcjr->array[0], 0, x >> 2, buffer32->line[(pcjr->displine << 1) + 1]);
        }
        pcjr->sc = oldsc;
        if (pcjr->vc == pcjr->crtc[7] && !pcjr->sc) {
            pcjr->stat |= 8;
        }
        pcjr->displine++;
        if (pcjr->displine >= 360)
            pcjr->displine = 0;
    } else {
        timer_advance_u64(&pcjr->timer, pcjr->dispontime);
        if (pcjr->dispon)
            pcjr->stat |= 1;
        pcjr->linepos = 0;
        if (pcjr->vsynctime) {
            pcjr->vsynctime--;
            if (!pcjr->vsynctime) {
                pcjr->stat &= ~8;
            }
        }
        if (pcjr->sc == (pcjr->crtc[11] & 31) || ((pcjr->crtc[8] & 3) == 3 && pcjr->sc == ((pcjr->crtc[11] & 31) >> 1))) {
            pcjr->con  = 0;
            pcjr->coff = 1;
        }
        if (pcjr->vadj) {
            pcjr->sc++;
            pcjr->sc &= 31;
            pcjr->ma = pcjr->maback;
            pcjr->vadj--;
            if (!pcjr->vadj) {
                pcjr->dispon = 1;
                pcjr->ma = pcjr->maback = (pcjr->crtc[13] | (pcjr->crtc[12] << 8)) & 0x3fff;
                pcjr->sc                = 0;
            }
        } else if (pcjr->sc == pcjr->crtc[9] || ((pcjr->crtc[8] & 3) == 3 && pcjr->sc == (pcjr->crtc[9] >> 1))) {
            pcjr->maback = pcjr->ma;
            pcjr->sc     = 0;
            oldvc        = pcjr->vc;
            pcjr->vc++;
            pcjr->vc &= 127;
            if (pcjr->vc == pcjr->crtc[6])
                pcjr->dispon = 0;
            if (oldvc == pcjr->crtc[4]) {
                pcjr->vc   = 0;
                pcjr->vadj = pcjr->crtc[5];
                if (!pcjr->vadj)
                    pcjr->dispon = 1;
                if (!pcjr->vadj)
                    pcjr->ma = pcjr->maback = (pcjr->crtc[13] | (pcjr->crtc[12] << 8)) & 0x3fff;
                if ((pcjr->crtc[10] & 0x60) == 0x20)
                    pcjr->cursoron = 0;
                else
                    pcjr->cursoron = pcjr->blink & 16;
            }
            if (pcjr->vc == pcjr->crtc[7]) {
                pcjr->dispon    = 0;
                pcjr->displine  = 0;
                pcjr->vsynctime = 16;
                picint(1 << 5);
                if (pcjr->crtc[7]) {
                    if (pcjr->array[0] & 1)
                        x = (pcjr->crtc[1] << 3) + 16;
                    else
                        x = (pcjr->crtc[1] << 4) + 16;
                    pcjr->lastline++;

                    xs_temp = x;
                    ys_temp = (pcjr->lastline - pcjr->firstline) << 1;

                    if ((xs_temp > 0) && (ys_temp > 0)) {
                        if (xs_temp < 64)
                            xs_temp = 656;
                        if (ys_temp < 32)
                            ys_temp = 400;
                        if (!enable_overscan)
                            xs_temp -= 16;

                        if ((xs_temp != xsize) || (ys_temp != ysize) || video_force_resize_get()) {
                            xsize = xs_temp;
                            ysize = ys_temp;
                            set_screen_size(xsize, ysize + (enable_overscan ? 16 : 0));

                            if (video_force_resize_get())
                                video_force_resize_set(0);
                        }

                        if (enable_overscan) {
                            if (pcjr->composite)
                                video_blit_memtoscreen(0, (pcjr->firstline - 4) << 1,
                                                       xsize, ((pcjr->lastline - pcjr->firstline) + 8) << 1);
                            else
                                video_blit_memtoscreen_8(0, (pcjr->firstline - 4) << 1,
                                                         xsize, ((pcjr->lastline - pcjr->firstline) + 8) << 1);
                        } else {
                            if (pcjr->composite)
                                video_blit_memtoscreen(8, pcjr->firstline << 1,
                                                       xsize, (pcjr->lastline - pcjr->firstline) << 1);
                            else
                                video_blit_memtoscreen_8(8, pcjr->firstline << 1,
                                                         xsize, (pcjr->lastline - pcjr->firstline) << 1);
                        }
                    }

                    frames++;
                    video_res_x = xsize;
                    video_res_y = ysize;
                }
                pcjr->firstline = 1000;
                pcjr->lastline  = 0;
                pcjr->blink++;
            }
        } else {
            pcjr->sc++;
            pcjr->sc &= 31;
            pcjr->ma = pcjr->maback;
        }
        if ((pcjr->sc == (pcjr->crtc[10] & 31) || ((pcjr->crtc[8] & 3) == 3 && pcjr->sc == ((pcjr->crtc[10] & 31) >> 1))))
            pcjr->con = 1;
    }
}

static void
kbd_write(uint16_t port, uint8_t val, void *priv)
{
    pcjr_t *pcjr = (pcjr_t *) priv;

    if ((port >= 0xa0) && (port <= 0xa7))
        port = 0xa0;

    switch (port) {
        case 0x60:
            pcjr->pa = val;
            break;

        case 0x61:
            pcjr->pb = val;

            timer_process();

            if (cassette != NULL)
                pc_cas_set_motor(cassette, (pcjr->pb & 0x08) == 0);

            speaker_update();
            speaker_gated  = val & 1;
            speaker_enable = val & 2;
            if (speaker_enable)
                was_speaker_enable = 1;
            pit_devs[0].set_gate(pit_devs[0].data, 2, val & 1);
            sn76489_mute = speaker_mute = 1;
            switch (val & 0x60) {
                case 0x00:
                    speaker_mute = 0;
                    break;

                case 0x60:
                    sn76489_mute = 0;
                    break;
            }
            break;

        case 0xa0:
            nmi_mask = val & 0x80;
            pit_devs[0].set_using_timer(pit_devs[0].data, 1, !(val & 0x20));
            break;
    }
}

static uint8_t
kbd_read(uint16_t port, void *priv)
{
    pcjr_t *pcjr = (pcjr_t *) priv;
    uint8_t ret  = 0xff;

    if ((port >= 0xa0) && (port <= 0xa7))
        port = 0xa0;

    switch (port) {
        case 0x60:
            ret = pcjr->pa;
            break;

        case 0x61:
            ret = pcjr->pb;
            break;

        case 0x62:
            ret = (pcjr->latched ? 1 : 0);
            ret |= 0x02; /*Modem card not installed*/
            if ((pcjr->pb & 0x08) || (cassette == NULL))
                ret |= (ppispeakon ? 0x10 : 0);
            else
                ret |= (pc_cas_get_inp(cassette) ? 0x10 : 0);
            ret |= (ppispeakon ? 0x10 : 0);
            ret |= (ppispeakon ? 0x20 : 0);
            ret |= (pcjr->data ? 0x40 : 0);
            if (pcjr->data)
                ret |= 0x40;
            break;

        case 0xa0:
            pcjr->latched = 0;
            ret           = 0;
            break;
    }

    return (ret);
}

static void
kbd_poll(void *priv)
{
    pcjr_t *pcjr = (pcjr_t *) priv;
    int     c, p = 0, key;

    timer_advance_u64(&pcjr->send_delay_timer, 220 * TIMER_USEC);

    if (key_queue_start != key_queue_end && !pcjr->serial_pos && !pcjr->latched) {
        key = key_queue[key_queue_start];

        key_queue_start = (key_queue_start + 1) & 0xf;

        pcjr->latched        = 1;
        pcjr->serial_data[0] = 1; /*Start bit*/
        pcjr->serial_data[1] = 0;

        for (c = 0; c < 8; c++) {
            if (key & (1 << c)) {
                pcjr->serial_data[(c + 1) * 2]     = 1;
                pcjr->serial_data[(c + 1) * 2 + 1] = 0;
                p++;
            } else {
                pcjr->serial_data[(c + 1) * 2]     = 0;
                pcjr->serial_data[(c + 1) * 2 + 1] = 1;
            }
        }

        if (p & 1) { /*Parity*/
            pcjr->serial_data[9 * 2]     = 1;
            pcjr->serial_data[9 * 2 + 1] = 0;
        } else {
            pcjr->serial_data[9 * 2]     = 0;
            pcjr->serial_data[9 * 2 + 1] = 1;
        }

        for (c = 0; c < 11; c++) { /*11 stop bits*/
            pcjr->serial_data[(c + 10) * 2]     = 0;
            pcjr->serial_data[(c + 10) * 2 + 1] = 0;
        }

        pcjr->serial_pos++;
    }

    if (pcjr->serial_pos) {
        pcjr->data = pcjr->serial_data[pcjr->serial_pos - 1];
        nmi        = pcjr->data;
        pcjr->serial_pos++;
        if (pcjr->serial_pos == 42 + 1)
            pcjr->serial_pos = 0;
    }
}

static void
kbd_adddata(uint16_t val)
{
    key_queue[key_queue_end] = val;
    key_queue_end            = (key_queue_end + 1) & 0xf;
}

static void
kbd_adddata_ex(uint16_t val)
{
    kbd_adddata_process(val, kbd_adddata);
}

static void
speed_changed(void *priv)
{
    pcjr_t *pcjr = (pcjr_t *) priv;

    recalc_timings(pcjr);
}

void
pit_irq0_timer_pcjr(int new_out, int old_out)
{
    if (new_out && !old_out) {
        picint(1);
        pit_devs[0].ctr_clock(pit_devs[0].data, 1);
    }

    if (!new_out)
        picintc(1);
}

static const device_config_t pcjr_config[] = {
  // clang-format off
    {
        .name = "display_type",
        .description = "Display type",
        .type = CONFIG_SELECTION,
        .default_string = "",
        .default_int = PCJR_RGB,
        .file_filter = "",
        .spinner = { 0 },
        .selection = {
            { .description = "RGB",       .value = PCJR_RGB       },
            { .description = "Composite", .value = PCJR_COMPOSITE },
            { .description = ""                                   }
        }
    },
    { .name = "", .description = "", .type = CONFIG_END }
  // clang-format on
};

const device_t pcjr_device = {
    "IBM PCjr",
    "pcjr",
    0,
    0,
    NULL,
    NULL,
    NULL,
    { NULL },
    speed_changed,
    NULL,
    pcjr_config
};

int
machine_pcjr_init(const machine_t *model)
{
    int     display_type;
    pcjr_t *pcjr;

    int ret;

    ret = bios_load_linear("roms/machines/ibmpcjr/bios.rom",
                           0x000f0000, 65536, 0);

    if (bios_only || !ret)
        return ret;

    pcjr = malloc(sizeof(pcjr_t));
    memset(pcjr, 0x00, sizeof(pcjr_t));
    pcjr->memctrl   = -1;
    display_type    = machine_get_config_int("display_type");
    pcjr->composite = (display_type != PCJR_RGB);

    pic_init_pcjr();
    pit_common_init(0, pit_irq0_timer_pcjr, NULL);

    cpu_set();

    /* Initialize the video controller. */
    video_reset(gfxcard);
    loadfont("roms/video/mda/mda.rom", 0);
    mem_mapping_add(&pcjr->mapping, 0xb8000, 0x08000,
                    vid_read, NULL, NULL,
                    vid_write, NULL, NULL, NULL, 0, pcjr);
    io_sethandler(0x03d0, 16,
                  vid_in, NULL, NULL, vid_out, NULL, NULL, pcjr);
    timer_add(&pcjr->timer, vid_poll, pcjr, 1);
    video_inform(VIDEO_FLAG_TYPE_CGA, &timing_dram);
    device_add_ex(&pcjr_device, pcjr);
    cga_palette = 0;
    cgapal_rebuild();

    /* Initialize the keyboard. */
    keyboard_scan   = 1;
    key_queue_start = key_queue_end = 0;
    io_sethandler(0x0060, 4,
                  kbd_read, NULL, NULL, kbd_write, NULL, NULL, pcjr);
    io_sethandler(0x00a0, 8,
                  kbd_read, NULL, NULL, kbd_write, NULL, NULL, pcjr);
    timer_add(&pcjr->send_delay_timer, kbd_poll, pcjr, 1);
    keyboard_set_table(scancode_xt);
    keyboard_send = kbd_adddata_ex;

    /* Technically it's the SN76496N, but the SN76489 is identical to the SN76496N. */
    device_add(&sn76489_device);

    nmi_mask = 0x80;

    device_add(&fdc_pcjr_device);

    device_add(&ns8250_pcjr_device);
    serial_set_next_inst(SERIAL_MAX); /* So that serial_standalone_init() won't do anything. */

    return ret;
}