(nw) amust : random musings

src/mame/drivers/amust.cpp

@@ -1,17 +1,22 @@
 // license:BSD-3-Clause
 // copyright-holders:Robbbert
-/***************************************************************************
+/*****************************************************************************************
 
 Amust Compak - also known as Amust Executive 816.
 
 2014-03-21 Skeleton driver. [Robbbert]
 
-An unusual-looking CP/M computer.
+An unusual-looking CP/M computer. The screen is a tiny CRT not much bigger
+than a modern smartphone.
+
+Z-80A @ 4MHz; 64KB dynamic RAM (8x 4164); 2KB video ram (6116); 2x 13cm drives;
+80 track DD with data capacity of 790KB; in a lockable Samsonite briefcase.
+
 There are no manuals or schematics known to exist.
 The entire driver is guesswork.
 The board has LH0080 (Z80A), 2x 8251, 2x 8255, 8253, uPD765A and a HD46505SP-2.
-The videoram is a 6116 RAM. There is a piezo beeper. There are 3 crystals,
+There is a piezo beeper. There are 3 crystals, X1 = 4.9152 (serial chips),
-X1 = 4.9152 (serial chips?), X2 = 16 (CPU), X3 = 14.31818 MHz (Video?).
+X2 = 16 (CPU), X3 = 14.31818 MHz (Video).
 There are numerous jumpers, all of which perform unknown functions.
 
 The keyboard is a plug-in unit, same idea as Kaypro and Zorba. It has these
@@ -50,21 +55,6 @@ Two Side
 Skew 1,3,5,2,4
 
 
-Stuff that doesn't make sense:
-------------------------------
-1. To access the screen, it waits for IRQ presumably from sync pulse. It sets INT
-mode 0 which means a page-zero jump, but doesn't write anything to the zero-page ram.
-That's why I added a RETI at 0038 and set the vector to there. A bit later it writes
-a jump at 0000. Then it sets the interrupting device to the fdc (not sure how yet),
-then proceeds to overwrite all of page-zero with the disk contents. This of course
-kills the jump it just wrote, and my RETI. So it runs into the weeds at high speed.
-What should happen is after loading the boot sector succesfully it will jump to 0000,
-otherwise it will write BOOT NG to the screen and you're in the monitor. The bios
-contains no RETI instructions.
-2. At F824 it copies itself to the same address which is presumably shadow ram. But
-it never switches to it. The ram is physically in the machine.
-
-
 Monitor Commands:
 -----------------
 B = Boot from floppy
@@ -73,12 +63,17 @@ B = Boot from floppy
 
 ToDo:
 - Everything
-- Need software
+- Floppy issues:
-- Keyboard controller needs to be emulated
+  - The loop to read a sector has no escape. The interrupt handler (which can't be found)
+    needs to take another path when the sector is complete.
+  - The loop uses "ini" to read a byte, but this doesn't clear DRQ, so memory rapidly fills
+    up with garbage, mostly FF.
+- Keyboard controller needs to be emulated.
 - If booting straight to CP/M, the load message should be in the middle of the screen.
+- Looks like port 5 has a row of function keys or similar. Need to be added.
 
 
-****************************************************************************/
+*******************************************************************************************/
 
 #include "emu.h"
 #include "cpu/z80/z80.h"
@@ -120,7 +115,6 @@ private:
 		TIMER_BEEP_OFF
 	};
 
-	DECLARE_MACHINE_RESET(amust);
 	DECLARE_READ8_MEMBER(port04_r);
 	DECLARE_WRITE8_MEMBER(port04_w);
 	DECLARE_READ8_MEMBER(port05_r);
@@ -132,18 +126,28 @@ private:
 	DECLARE_READ8_MEMBER(port0a_r);
 	DECLARE_WRITE8_MEMBER(port0a_w);
 	DECLARE_WRITE8_MEMBER(port0d_w);
+	DECLARE_WRITE_LINE_MEMBER(hsync_w);
+	DECLARE_WRITE_LINE_MEMBER(vsync_w);
+	DECLARE_WRITE_LINE_MEMBER(drq_w);
+	DECLARE_WRITE_LINE_MEMBER(intrq_w);
 	void kbd_put(u8 data);
-	INTERRUPT_GEN_MEMBER(irq_vs);
 	MC6845_UPDATE_ROW(crtc_update_row);
 
 	void io_map(address_map &map);
 	void mem_map(address_map &map);
+	void machine_reset() override;
+	void do_int();
 
 	u8 m_port04;
 	u8 m_port06;
 	u8 m_port08;
+	u8 m_port09;
 	u8 m_port0a;
 	u8 m_term_data;
+	bool m_drq;
+	//bool m_intrq;
+	bool m_hsync;
+	bool m_vsync;
 	virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) override;
 	required_device<palette_device> m_palette;
 	required_device<cpu_device> m_maincpu;
@@ -211,21 +215,60 @@ static void amust_floppies(device_slot_interface &device)
 static INPUT_PORTS_START( amust )
 	PORT_START("P9")
 	// bits 6,7 not used?
-	PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_UNKNOWN ) // code @ FB83
+	// bit 5 - fdc intrq
+	PORT_DIPNAME( 0x01, 0x01, "Bit0" ) // code @ FC99
+	PORT_DIPSETTING(    0x01, DEF_STR( On ) )
+	PORT_DIPSETTING(    0x00, DEF_STR( Off ) )
+	PORT_DIPNAME( 0x02, 0x02, "Bit1" )
+	PORT_DIPSETTING(    0x02, DEF_STR( On ) )
+	PORT_DIPSETTING(    0x00, DEF_STR( Off ) )
+	PORT_DIPNAME( 0x04, 0x04, "Bit2" )
+	PORT_DIPSETTING(    0x04, DEF_STR( On ) )
+	PORT_DIPSETTING(    0x00, DEF_STR( Off ) )
+	PORT_DIPNAME( 0x08, 0x08, "Bit3" )
+	PORT_DIPSETTING(    0x08, DEF_STR( On ) )
+	PORT_DIPSETTING(    0x00, DEF_STR( Off ) )
 	PORT_DIPNAME( 0x10, 0x10, "Boot to Monitor" ) // code @ F895
 	PORT_DIPSETTING(    0x00, DEF_STR( Off ) )
 	PORT_DIPSETTING(    0x10, DEF_STR( On ) )
-	PORT_DIPNAME( 0x0f, 0x01, "Unknown" ) // code @ FC99
-	PORT_DIPSETTING(    0x01, "1" )
-	PORT_DIPSETTING(    0x02, "2" )
-	PORT_DIPSETTING(    0x04, "3" )
-	PORT_DIPSETTING(    0x08, "4" )
 INPUT_PORTS_END
 
-// bodgy
+void amust_state::do_int()
-INTERRUPT_GEN_MEMBER( amust_state::irq_vs )
 {
-	m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, ASSERT_LINE, 0xff);
+	bool sync = m_hsync | m_vsync;
+
+	if ((BIT(m_port0a, 3) && sync)             // when writing to the screen, only do it during blanking
+		|| (BIT(m_port0a, 5) && m_drq))        // when reading from floppy, only do it when DRQ is high.
+	{
+		//printf("%X,%X,%X ",m_port0a,sync,m_drq);
+		m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, ASSERT_LINE, 0x00);
+	}
+	else
+		m_maincpu->set_input_line(INPUT_LINE_IRQ0, CLEAR_LINE);
+}
+
+WRITE_LINE_MEMBER( amust_state::drq_w )
+{
+	m_drq = state;
+	do_int();
+	m_fdc->tc_w(1);
+}
+
+WRITE_LINE_MEMBER( amust_state::intrq_w )
+{
+	m_port09 = (m_port09 & 0xdf) | (state ? 0x20 : 0);
+}
+
+WRITE_LINE_MEMBER( amust_state::hsync_w )
+{
+	m_hsync = state;
+	do_int();
+}
+
+WRITE_LINE_MEMBER( amust_state::vsync_w )
+{
+	m_vsync = state;
+	do_int();
 }
 
 READ8_MEMBER( amust_state::port04_r )
@@ -271,14 +314,14 @@ d1 -
 d2 -
 d3 -
 d4 - H = go to monitor; L = boot from disk
-d5 - status of disk-related; loops till NZ
+d5 - status of fdc intrq; loops till NZ
 d6 -
 d7 -
 */
 READ8_MEMBER( amust_state::port09_r )
 {
 	logerror("%s\n",machine().describe_context());
-	return ioport("P9")->read();
+	return (ioport("P9")->read() & 0x1f) | m_port09;
 }
 
 READ8_MEMBER( amust_state::port0a_r )
@@ -302,6 +345,14 @@ WRITE8_MEMBER( amust_state::port0a_w )
 		m_beep->set_state(1);
 		timer_set(attotime::from_msec(150), TIMER_BEEP_OFF);
 	}
+	floppy_image_device *floppy = m_floppy0->get_device();
+	m_fdc->set_floppy(floppy);
+	if (floppy)
+	{
+		floppy->mon_w(0);
+
+		//floppy->ss_w(0);   // side 0? hopefully fdc does this
+	}
 }
 
 WRITE8_MEMBER( amust_state::port0d_w )
@@ -357,17 +408,20 @@ MC6845_UPDATE_ROW( amust_state::crtc_update_row )
 	}
 }
 
-MACHINE_RESET_MEMBER( amust_state, amust )
+void amust_state::machine_reset()
 {
 	membank("bankr0")->set_entry(0); // point at rom
 	membank("bankw0")->set_entry(0); // always write to ram
-	address_space &space = m_maincpu->space(AS_PROGRAM);
-	space.write_byte(0x38, 0xed);
-	space.write_byte(0x39, 0x4d);
 	m_port04 = 0;
 	m_port06 = 0;
 	m_port08 = 0;
+	m_port09 = 0;
 	m_port0a = 0;
+	m_hsync = false;
+	m_vsync = false;
+	m_drq = false;
+	m_fdc->set_ready_line_connected(1); // always ready for minifloppy; controlled by fdc for 20cm
+	m_fdc->set_unscaled_clock(4000000); // 4MHz for minifloppy; 8MHz for 20cm
 	m_maincpu->set_state_int(Z80_PC, 0xf800);
 }
 
@@ -385,8 +439,6 @@ MACHINE_CONFIG_START(amust_state::amust)
 	MCFG_DEVICE_ADD("maincpu",Z80, XTAL(16'000'000) / 4)
 	MCFG_DEVICE_PROGRAM_MAP(mem_map)
 	MCFG_DEVICE_IO_MAP(io_map)
-	MCFG_DEVICE_VBLANK_INT_DRIVER("screen", amust_state, irq_vs)
-	MCFG_MACHINE_RESET_OVERRIDE(amust_state, amust)
 
 	/* video hardware */
 	MCFG_SCREEN_ADD_MONOCHROME("screen", RASTER, rgb_t::green())
@@ -408,8 +460,12 @@ MACHINE_CONFIG_START(amust_state::amust)
 	MCFG_MC6845_SHOW_BORDER_AREA(false)
 	MCFG_MC6845_CHAR_WIDTH(8)
 	MCFG_MC6845_UPDATE_ROW_CB(amust_state, crtc_update_row)
+	MCFG_MC6845_OUT_HSYNC_CB(WRITELINE(*this, amust_state, hsync_w))
+	MCFG_MC6845_OUT_VSYNC_CB(WRITELINE(*this, amust_state, vsync_w))
 
-	MCFG_UPD765A_ADD("fdc", false, true)
+	UPD765A(config, m_fdc, true, true);
+	m_fdc->drq_wr_callback().set(FUNC(amust_state::drq_w));
+	m_fdc->intrq_wr_callback().set(FUNC(amust_state::intrq_w));
 	MCFG_FLOPPY_DRIVE_ADD("fdc:0", amust_floppies, "525qd", floppy_image_device::default_floppy_formats)
 	MCFG_FLOPPY_DRIVE_SOUND(true)
 	MCFG_FLOPPY_DRIVE_ADD("fdc:1", amust_floppies, "525qd", floppy_image_device::default_floppy_formats)
@@ -454,13 +510,13 @@ MACHINE_CONFIG_END
 /* ROM definition */
 ROM_START( amust )
 	ROM_REGION( 0x11000, "maincpu", ROMREGION_ERASEFF )
-	ROM_LOAD( "mon_h.rom", 0x10000, 0x1000, CRC(10dceac6) SHA1(1ef80039063f7a6455563d59f1bcc23e09eca369) )
+	ROM_LOAD( "mon_h.ic25", 0x10000, 0x1000, CRC(10dceac6) SHA1(1ef80039063f7a6455563d59f1bcc23e09eca369) )
 
 	ROM_REGION( 0x800, "chargen", 0 )
-	ROM_LOAD( "cg4.rom", 0x000, 0x800, CRC(52e7b9d8) SHA1(cc6d457634eb688ccef471f72bddf0424e64b045) )
+	ROM_LOAD( "cg4.ic74",   0x000, 0x800, CRC(52e7b9d8) SHA1(cc6d457634eb688ccef471f72bddf0424e64b045) )
 
 	ROM_REGION( 0x800, "keyboard", 0 )
-	ROM_LOAD( "kbd_3.rom", 0x000, 0x800, CRC(d9441b35) SHA1(ce250ab1e892a13fd75182703f259855388c6bf4) )
+	ROM_LOAD( "kbd_3.rom",  0x000, 0x800, CRC(d9441b35) SHA1(ce250ab1e892a13fd75182703f259855388c6bf4) )
 
 	ROM_REGION( 0x800, "videoram", ROMREGION_ERASE00 )
 ROM_END