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// license:BSD-3-Clause
// copyright-holders:Miodrag Milanovic, Jonathan Gevaryahu
/***************************************************************************

        DEC VT520

        02/07/2009 Skeleton driver.

****************************************************************************/

#include "emu.h"
#include "cpu/mcs51/mcs51.h"
//#include "machine/mc68681.h"
#include "machine/ram.h"
#include "emupal.h"
#include "screen.h"


class vt520_state : public driver_device
{
public:
	vt520_state(const machine_config &mconfig, device_type type, const char *tag)
		: driver_device(mconfig, type, tag) ,
		m_maincpu(*this, "maincpu"),
		m_rom(*this, "maincpu") { }

	void vt520(machine_config &config);
	void vt420(machine_config &config);

private:
	DECLARE_READ8_MEMBER(vt520_some_r);
	virtual void machine_reset() override;
	virtual void video_start() override;
	uint32_t screen_update_vt520(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect);
	required_device<cpu_device> m_maincpu;
	required_region_ptr<uint8_t> m_rom;
	void vt520_io(address_map &map);
	void vt520_mem(address_map &map);
};


void vt520_state::vt520_mem(address_map &map)
{
	map(0x0000, 0xffff).bankrw("bank1");
}

/*
    On the board there is TC160G41AF (1222) custom chip
    doing probably all video/uart logic
    there is 43.320MHz xtal near by
*/

READ8_MEMBER( vt520_state::vt520_some_r )
{
	//bit 5 0
	//bit 6 1
	return 0x40;
}

void vt520_state::vt520_io(address_map &map)
{
	map.unmap_value_high();
	map(0x7ffb, 0x7ffb).r(FUNC(vt520_state::vt520_some_r));
}

/* Input ports */
static INPUT_PORTS_START( vt520 )
INPUT_PORTS_END


void vt520_state::machine_reset()
{
	address_space &space = m_maincpu->space(AS_PROGRAM);
	space.unmap_write(0x0000, 0xffff);
	membank("bank1")->set_base(&m_rom[m_rom.length() - 0x10000]);
}

void vt520_state::video_start()
{
}

uint32_t vt520_state::screen_update_vt520(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	return 0;
}

MACHINE_CONFIG_START(vt520_state::vt420)
	/* basic machine hardware */
	MCFG_DEVICE_ADD("maincpu", I80C31, XTAL(43'320'000) / 3) // SCN8031HCFN40 (divider not verified)
	MCFG_DEVICE_PROGRAM_MAP(vt520_mem)
	MCFG_DEVICE_IO_MAP(vt520_io)

	/* video hardware */
	MCFG_SCREEN_ADD("screen", RASTER)
	MCFG_SCREEN_REFRESH_RATE(50)
	MCFG_SCREEN_VBLANK_TIME(ATTOSECONDS_IN_USEC(2500)) /* not accurate */
	MCFG_SCREEN_SIZE(802, 480)
	MCFG_SCREEN_VISIBLE_AREA(0, 802-1, 0, 480-1)
	MCFG_SCREEN_UPDATE_DRIVER(vt520_state, screen_update_vt520)
	MCFG_SCREEN_PALETTE("palette")

	MCFG_PALETTE_ADD_MONOCHROME("palette")
MACHINE_CONFIG_END

MACHINE_CONFIG_START(vt520_state::vt520)
	/* basic machine hardware */
	MCFG_DEVICE_ADD("maincpu", I80C32, XTAL(20'000'000)) // Philips P80C32IBPN
	MCFG_DEVICE_PROGRAM_MAP(vt520_mem)
	MCFG_DEVICE_IO_MAP(vt520_io)

	/* video hardware */
	MCFG_SCREEN_ADD("screen", RASTER)
	MCFG_SCREEN_REFRESH_RATE(50)
	MCFG_SCREEN_VBLANK_TIME(ATTOSECONDS_IN_USEC(2500)) /* not accurate */
	MCFG_SCREEN_SIZE(802, 480)
	MCFG_SCREEN_VISIBLE_AREA(0, 802-1, 0, 480-1)
	MCFG_SCREEN_UPDATE_DRIVER(vt520_state, screen_update_vt520)
	MCFG_SCREEN_PALETTE("palette")

	MCFG_PALETTE_ADD_MONOCHROME("palette")

	// On the board there are two M5M44256BJ-7 chips
	// Which are DRAM 256K x 4bit
	/* internal ram */
	MCFG_RAM_ADD(RAM_TAG)
	MCFG_RAM_DEFAULT_SIZE("256K")
MACHINE_CONFIG_END

/**************************************************************************************************************

DEC VT420.
Chips: SCN8031HCFN40, SCN2681TC1N40, M5M4464AP, HM62256LFP-10T, TC23SC070AT, TC531001CP-1815
Crystals: 43.320

***************************************************************************************************************/

ROM_START( vt420 )
	ROM_REGION(0x20000, "maincpu", 0)
	ROM_LOAD( "23-068e9-00.e2", 0x00000, 0x20000, CRC(22c3f93b) SHA1(b212911c41e4dba2e09d91fdd1f72d6c7536b0af) )
ROM_END

ROM_START( vt520 )
	ROM_REGION( 0x80000, "maincpu", ROMREGION_ERASEFF )
	ROM_LOAD( "23-010ed-00.e20", 0x0000, 0x80000, CRC(2502cc22) SHA1(0437c3107412f69e09d050fef003f2a81d8a3163)) // "(C)DEC94 23-010ED-00 // 9739 D" dumped from a VT520-A4 model
ROM_END

/* Driver */

COMP( 1990, vt420, 0, 0, vt420, vt520, vt520_state, empty_init, "Digital Equipment Corporation", "VT420 Video Terminal", MACHINE_IS_SKELETON )
//COMP( 1993, vt510, 0, 0, vt520, vt520, vt520_state, empty_init, "Digital Equipment Corporation", "VT510 Video Terminal",  MACHINE_IS_SKELETON)
COMP( 1994, vt520, 0, 0, vt520, vt520, vt520_state, empty_init, "Digital Equipment Corporation", "VT520 Video Terminal",  MACHINE_IS_SKELETON)
//COMP( 1994, vt525, 0, 0, vt520, vt520, vt520_state, empty_init, "Digital Equipment Corporation", "VT525 Video Terminal",  MACHINE_IS_SKELETON)