// license:BSD-3-Clause
// copyright-holders:Robbbert
/***************************************************************************
David Griffiths DG640 Video Display Unit.
It was sold by Applied Technology. It uses a MCM6574 as a character generator.
The DG640 also supports blinking, reverse-video, and LORES graphics.
It is a S100 card, originally called "ETI 640" when it was first described
in the April 1978 issue of Electronics Today International (Australia).
****************************************************************************/
#include "emu.h"
#include "dg640.h"
#include "emupal.h"
#include "screen.h"
DEFINE_DEVICE_TYPE(S100_DG640, dg640_device, "dg640", "DG640 VDU")
dg640_device::dg640_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock)
: device_t(mconfig, S100_DG640, tag, owner, clock)
, device_s100_card_interface(mconfig, *this)
, m_p_chargen(*this, "chargen")
, m_dsw(*this, "DSW")
{}
void dg640_device::device_start()
{
m_p_videoram = make_unique_clear<u8[]>(0x400);
save_pointer(NAME(m_p_videoram), 0x400);
m_p_attribram = make_unique_clear<u8[]>(0x400);
save_pointer(NAME(m_p_attribram), 0x400);
}
uint32_t dg640_device::screen_update(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
// attributes bit 0 = flash, bit 1 = lores. Also bit 7 of the character = reverse-video (text only).
uint8_t y,ra,chr,gfx,attr,inv,gfxbit;
uint16_t sy=0,ma=0,x;
bool flash;
m_framecnt++;
for (y = 0; y < 16; y++)
{
for (ra = 0; ra < 16; ra++)
{
uint16_t *p = &bitmap.pix16(sy++);
for (x = ma; x < ma + 64; x++)
{
attr = m_p_attribram[x];
chr = m_p_videoram[x];
flash = BIT(m_framecnt, 4) & BIT(attr, 0);
if (BIT(attr, 1)) // lores gfx - can flash
{
if (flash) chr = 0; // blank part of flashing
gfxbit = (ra & 0x0c)>>1;
/* Display one line of a lores character (8 pixels) */
*p++ = BIT(chr, gfxbit);
*p++ = BIT(chr, gfxbit);
*p++ = BIT(chr, gfxbit);
*p++ = BIT(chr, gfxbit);
gfxbit++;
*p++ = BIT(chr, gfxbit);
*p++ = BIT(chr, gfxbit);
*p++ = BIT(chr, gfxbit);
*p++ = BIT(chr, gfxbit);
}
else
{
gfx = 0;
if (!flash)
{
inv = BIT(chr, 7) ? 0xff : 0; // text with bit 7 high is reversed
chr &= 0x7f;
gfx = inv;
// if g,j,p,q,y; lower the descender
if ((chr==0x2c)||(chr==0x3b)||(chr==0x67)||(chr==0x6a)||(chr==0x70)||(chr==0x71)||(chr==0x79))
{
if (ra > 6)
gfx = m_p_chargen[(chr<<4) | (ra-7) ] ^ inv;
}
else
{
if ((ra > 3) & (ra < 13))
gfx = m_p_chargen[(chr<<4) | (ra-4) ] ^ inv;
}
}
/* Display a scanline of a character */
*p++ = BIT(gfx, 7);
*p++ = BIT(gfx, 6);
*p++ = BIT(gfx, 5);
*p++ = BIT(gfx, 4);
*p++ = BIT(gfx, 3);
*p++ = BIT(gfx, 2);
*p++ = BIT(gfx, 1);
*p++ = BIT(gfx, 0);
}
}
}
ma+=64;
}
return 0;
}
u8 dg640_device::s100_smemr_r(offs_t offset)
{
if (m_dsw->read() != (offset & 0xf800) >> 11)
return 0xff;
if ((offset & 0x400) == 0)
return m_p_videoram[offset & 0x3ff];
else
return m_p_attribram[offset & 0x3ff];
}
void dg640_device::s100_mwrt_w(offs_t offset, u8 data)
{
if (m_dsw->read() != (offset & 0xf800) >> 11)
return;
if ((offset & 0x400) == 0)
m_p_videoram[offset & 0x3ff] = data;
else
m_p_attribram[offset & 0x3ff] = data;
}
static INPUT_PORTS_START(dg640)
PORT_START("DSW")
PORT_DIPNAME(0x1f, 0x0f, "Base Address") PORT_DIPLOCATION("SW1:1,2,3,4,5")
PORT_DIPSETTING(0x00, "0000")
PORT_DIPSETTING(0x01, "0800")
PORT_DIPSETTING(0x02, "1000")
PORT_DIPSETTING(0x03, "1800")
PORT_DIPSETTING(0x04, "2000")
PORT_DIPSETTING(0x05, "2800")
PORT_DIPSETTING(0x06, "3000")
PORT_DIPSETTING(0x07, "3800")
PORT_DIPSETTING(0x08, "4000")
PORT_DIPSETTING(0x09, "4800")
PORT_DIPSETTING(0x0a, "5000")
PORT_DIPSETTING(0x0b, "5800")
PORT_DIPSETTING(0x0c, "6000")
PORT_DIPSETTING(0x0d, "6800")
PORT_DIPSETTING(0x0e, "7000")
PORT_DIPSETTING(0x0f, "7800")
PORT_DIPSETTING(0x10, "8000")
PORT_DIPSETTING(0x11, "8800")
PORT_DIPSETTING(0x12, "9000")
PORT_DIPSETTING(0x13, "9800")
PORT_DIPSETTING(0x14, "A000")
PORT_DIPSETTING(0x15, "A800")
PORT_DIPSETTING(0x16, "B000")
PORT_DIPSETTING(0x17, "B800")
PORT_DIPSETTING(0x18, "C000")
PORT_DIPSETTING(0x19, "C800")
PORT_DIPSETTING(0x1a, "D000")
PORT_DIPSETTING(0x1b, "D800")
PORT_DIPSETTING(0x1c, "E000")
PORT_DIPSETTING(0x1d, "E800")
PORT_DIPSETTING(0x1e, "F000")
PORT_DIPSETTING(0x1f, "F800")
INPUT_PORTS_END
ioport_constructor dg640_device::device_input_ports() const
{
return INPUT_PORTS_NAME(dg640);
}
/* F4 Character Displayer */
static const gfx_layout dg640_charlayout =
{
7, 9, /* 7 x 9 characters */
128, /* 128 characters */
1, /* 1 bits per pixel */
{ 0 }, /* no bitplanes */
/* x offsets */
{ 0, 1, 2, 3, 4, 5, 6 },
/* y offsets */
{ 0*8, 1*8, 2*8, 3*8, 4*8, 5*8, 6*8, 7*8, 8*8 },
8*16 /* every char takes 16 bytes */
};
static GFXDECODE_START( gfx_dg640 )
GFXDECODE_ENTRY( "chargen", 0x0000, dg640_charlayout, 0, 1 )
GFXDECODE_END
void dg640_device::device_add_mconfig(machine_config &config)
{
screen_device &screen(SCREEN(config, "screen", SCREEN_TYPE_RASTER));
screen.set_color(rgb_t::amber());
screen.set_raw(12_MHz_XTAL, 768, 0, 512, 312, 0, 256); // 15625 Hz horizontal
screen.set_screen_update(FUNC(dg640_device::screen_update));
screen.set_palette("palette");
GFXDECODE(config, "gfxdecode", "palette", gfx_dg640);
PALETTE(config, "palette", palette_device::MONOCHROME);
}
ROM_START(dg640)
ROM_REGION( 0x0800, "chargen", 0 )
ROM_LOAD( "6574.bin", 0x0000, 0x0800, CRC(fd75df4f) SHA1(4d09aae2f933478532b7d3d1a2dee7123d9828ca) )
ROM_FILL(0, 16, 0x00)
ROM_END
const tiny_rom_entry *dg640_device::device_rom_region() const
{
return ROM_NAME(dg640);
}