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(nw) amust : random musings
This commit is contained in:
Robbbert
parent
33e96886bd
commit
4297917206
@ -1,17 +1,22 @@
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// license:BSD-3-Clause
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// copyright-holders:Robbbert
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/***************************************************************************
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/*****************************************************************************************
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Amust Compak - also known as Amust Executive 816.
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2014-03-21 Skeleton driver. [Robbbert]
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An unusual-looking CP/M computer.
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An unusual-looking CP/M computer. The screen is a tiny CRT not much bigger
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than a modern smartphone.
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Z-80A @ 4MHz; 64KB dynamic RAM (8x 4164); 2KB video ram (6116); 2x 13cm drives;
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80 track DD with data capacity of 790KB; in a lockable Samsonite briefcase.
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There are no manuals or schematics known to exist.
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The entire driver is guesswork.
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The board has LH0080 (Z80A), 2x 8251, 2x 8255, 8253, uPD765A and a HD46505SP-2.
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The videoram is a 6116 RAM. There is a piezo beeper. There are 3 crystals,
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X1 = 4.9152 (serial chips?), X2 = 16 (CPU), X3 = 14.31818 MHz (Video?).
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There is a piezo beeper. There are 3 crystals, X1 = 4.9152 (serial chips),
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X2 = 16 (CPU), X3 = 14.31818 MHz (Video).
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There are numerous jumpers, all of which perform unknown functions.
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The keyboard is a plug-in unit, same idea as Kaypro and Zorba. It has these
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@ -50,21 +55,6 @@ Two Side
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Skew 1,3,5,2,4
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Stuff that doesn't make sense:
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------------------------------
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1. To access the screen, it waits for IRQ presumably from sync pulse. It sets INT
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mode 0 which means a page-zero jump, but doesn't write anything to the zero-page ram.
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That's why I added a RETI at 0038 and set the vector to there. A bit later it writes
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a jump at 0000. Then it sets the interrupting device to the fdc (not sure how yet),
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then proceeds to overwrite all of page-zero with the disk contents. This of course
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kills the jump it just wrote, and my RETI. So it runs into the weeds at high speed.
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What should happen is after loading the boot sector succesfully it will jump to 0000,
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otherwise it will write BOOT NG to the screen and you're in the monitor. The bios
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contains no RETI instructions.
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2. At F824 it copies itself to the same address which is presumably shadow ram. But
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it never switches to it. The ram is physically in the machine.
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Monitor Commands:
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-----------------
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B = Boot from floppy
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@ -73,12 +63,17 @@ B = Boot from floppy
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ToDo:
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- Everything
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- Need software
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- Keyboard controller needs to be emulated
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- Floppy issues:
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- The loop to read a sector has no escape. The interrupt handler (which can't be found)
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needs to take another path when the sector is complete.
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- The loop uses "ini" to read a byte, but this doesn't clear DRQ, so memory rapidly fills
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up with garbage, mostly FF.
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- Keyboard controller needs to be emulated.
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- If booting straight to CP/M, the load message should be in the middle of the screen.
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- Looks like port 5 has a row of function keys or similar. Need to be added.
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****************************************************************************/
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*******************************************************************************************/
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#include "emu.h"
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#include "cpu/z80/z80.h"
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@ -120,7 +115,6 @@ private:
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TIMER_BEEP_OFF
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};
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DECLARE_MACHINE_RESET(amust);
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DECLARE_READ8_MEMBER(port04_r);
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DECLARE_WRITE8_MEMBER(port04_w);
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DECLARE_READ8_MEMBER(port05_r);
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@ -132,18 +126,28 @@ private:
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DECLARE_READ8_MEMBER(port0a_r);
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DECLARE_WRITE8_MEMBER(port0a_w);
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DECLARE_WRITE8_MEMBER(port0d_w);
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DECLARE_WRITE_LINE_MEMBER(hsync_w);
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DECLARE_WRITE_LINE_MEMBER(vsync_w);
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DECLARE_WRITE_LINE_MEMBER(drq_w);
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DECLARE_WRITE_LINE_MEMBER(intrq_w);
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void kbd_put(u8 data);
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INTERRUPT_GEN_MEMBER(irq_vs);
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MC6845_UPDATE_ROW(crtc_update_row);
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void io_map(address_map &map);
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void mem_map(address_map &map);
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void machine_reset() override;
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void do_int();
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u8 m_port04;
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u8 m_port06;
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u8 m_port08;
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u8 m_port09;
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u8 m_port0a;
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u8 m_term_data;
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bool m_drq;
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//bool m_intrq;
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bool m_hsync;
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bool m_vsync;
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virtual void device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr) override;
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required_device<palette_device> m_palette;
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required_device<cpu_device> m_maincpu;
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@ -211,21 +215,60 @@ static void amust_floppies(device_slot_interface &device)
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static INPUT_PORTS_START( amust )
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PORT_START("P9")
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// bits 6,7 not used?
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PORT_BIT( 0x20, IP_ACTIVE_LOW, IPT_UNKNOWN ) // code @ FB83
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// bit 5 - fdc intrq
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PORT_DIPNAME( 0x01, 0x01, "Bit0" ) // code @ FC99
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PORT_DIPSETTING( 0x01, DEF_STR( On ) )
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PORT_DIPSETTING( 0x00, DEF_STR( Off ) )
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PORT_DIPNAME( 0x02, 0x02, "Bit1" )
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PORT_DIPSETTING( 0x02, DEF_STR( On ) )
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PORT_DIPSETTING( 0x00, DEF_STR( Off ) )
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PORT_DIPNAME( 0x04, 0x04, "Bit2" )
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PORT_DIPSETTING( 0x04, DEF_STR( On ) )
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PORT_DIPSETTING( 0x00, DEF_STR( Off ) )
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PORT_DIPNAME( 0x08, 0x08, "Bit3" )
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PORT_DIPSETTING( 0x08, DEF_STR( On ) )
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PORT_DIPSETTING( 0x00, DEF_STR( Off ) )
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PORT_DIPNAME( 0x10, 0x10, "Boot to Monitor" ) // code @ F895
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PORT_DIPSETTING( 0x00, DEF_STR( Off ) )
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PORT_DIPSETTING( 0x10, DEF_STR( On ) )
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PORT_DIPNAME( 0x0f, 0x01, "Unknown" ) // code @ FC99
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PORT_DIPSETTING( 0x01, "1" )
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PORT_DIPSETTING( 0x02, "2" )
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PORT_DIPSETTING( 0x04, "3" )
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PORT_DIPSETTING( 0x08, "4" )
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INPUT_PORTS_END
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// bodgy
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INTERRUPT_GEN_MEMBER( amust_state::irq_vs )
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void amust_state::do_int()
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{
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m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, ASSERT_LINE, 0xff);
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bool sync = m_hsync | m_vsync;
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if ((BIT(m_port0a, 3) && sync) // when writing to the screen, only do it during blanking
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|| (BIT(m_port0a, 5) && m_drq)) // when reading from floppy, only do it when DRQ is high.
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{
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//printf("%X,%X,%X ",m_port0a,sync,m_drq);
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m_maincpu->set_input_line_and_vector(INPUT_LINE_IRQ0, ASSERT_LINE, 0x00);
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}
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else
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m_maincpu->set_input_line(INPUT_LINE_IRQ0, CLEAR_LINE);
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}
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WRITE_LINE_MEMBER( amust_state::drq_w )
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{
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m_drq = state;
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do_int();
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m_fdc->tc_w(1);
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}
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WRITE_LINE_MEMBER( amust_state::intrq_w )
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{
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m_port09 = (m_port09 & 0xdf) | (state ? 0x20 : 0);
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}
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WRITE_LINE_MEMBER( amust_state::hsync_w )
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{
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m_hsync = state;
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do_int();
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}
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WRITE_LINE_MEMBER( amust_state::vsync_w )
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{
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m_vsync = state;
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do_int();
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}
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READ8_MEMBER( amust_state::port04_r )
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@ -271,14 +314,14 @@ d1 -
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d2 -
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d3 -
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d4 - H = go to monitor; L = boot from disk
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d5 - status of disk-related; loops till NZ
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d5 - status of fdc intrq; loops till NZ
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d6 -
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d7 -
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*/
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READ8_MEMBER( amust_state::port09_r )
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{
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logerror("%s\n",machine().describe_context());
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return ioport("P9")->read();
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return (ioport("P9")->read() & 0x1f) | m_port09;
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}
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READ8_MEMBER( amust_state::port0a_r )
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@ -302,6 +345,14 @@ WRITE8_MEMBER( amust_state::port0a_w )
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m_beep->set_state(1);
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timer_set(attotime::from_msec(150), TIMER_BEEP_OFF);
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}
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floppy_image_device *floppy = m_floppy0->get_device();
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m_fdc->set_floppy(floppy);
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if (floppy)
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{
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floppy->mon_w(0);
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//floppy->ss_w(0); // side 0? hopefully fdc does this
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}
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}
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WRITE8_MEMBER( amust_state::port0d_w )
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@ -357,17 +408,20 @@ MC6845_UPDATE_ROW( amust_state::crtc_update_row )
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}
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}
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MACHINE_RESET_MEMBER( amust_state, amust )
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void amust_state::machine_reset()
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{
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membank("bankr0")->set_entry(0); // point at rom
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membank("bankw0")->set_entry(0); // always write to ram
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address_space &space = m_maincpu->space(AS_PROGRAM);
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space.write_byte(0x38, 0xed);
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space.write_byte(0x39, 0x4d);
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m_port04 = 0;
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m_port06 = 0;
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m_port08 = 0;
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m_port09 = 0;
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m_port0a = 0;
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m_hsync = false;
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m_vsync = false;
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m_drq = false;
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m_fdc->set_ready_line_connected(1); // always ready for minifloppy; controlled by fdc for 20cm
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m_fdc->set_unscaled_clock(4000000); // 4MHz for minifloppy; 8MHz for 20cm
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m_maincpu->set_state_int(Z80_PC, 0xf800);
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}
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@ -385,8 +439,6 @@ MACHINE_CONFIG_START(amust_state::amust)
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MCFG_DEVICE_ADD("maincpu",Z80, XTAL(16'000'000) / 4)
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MCFG_DEVICE_PROGRAM_MAP(mem_map)
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MCFG_DEVICE_IO_MAP(io_map)
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MCFG_DEVICE_VBLANK_INT_DRIVER("screen", amust_state, irq_vs)
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MCFG_MACHINE_RESET_OVERRIDE(amust_state, amust)
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/* video hardware */
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MCFG_SCREEN_ADD_MONOCHROME("screen", RASTER, rgb_t::green())
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@ -408,8 +460,12 @@ MACHINE_CONFIG_START(amust_state::amust)
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MCFG_MC6845_SHOW_BORDER_AREA(false)
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MCFG_MC6845_CHAR_WIDTH(8)
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MCFG_MC6845_UPDATE_ROW_CB(amust_state, crtc_update_row)
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MCFG_MC6845_OUT_HSYNC_CB(WRITELINE(*this, amust_state, hsync_w))
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MCFG_MC6845_OUT_VSYNC_CB(WRITELINE(*this, amust_state, vsync_w))
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MCFG_UPD765A_ADD("fdc", false, true)
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UPD765A(config, m_fdc, true, true);
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m_fdc->drq_wr_callback().set(FUNC(amust_state::drq_w));
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m_fdc->intrq_wr_callback().set(FUNC(amust_state::intrq_w));
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MCFG_FLOPPY_DRIVE_ADD("fdc:0", amust_floppies, "525qd", floppy_image_device::default_floppy_formats)
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MCFG_FLOPPY_DRIVE_SOUND(true)
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MCFG_FLOPPY_DRIVE_ADD("fdc:1", amust_floppies, "525qd", floppy_image_device::default_floppy_formats)
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@ -454,13 +510,13 @@ MACHINE_CONFIG_END
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/* ROM definition */
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ROM_START( amust )
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ROM_REGION( 0x11000, "maincpu", ROMREGION_ERASEFF )
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ROM_LOAD( "mon_h.rom", 0x10000, 0x1000, CRC(10dceac6) SHA1(1ef80039063f7a6455563d59f1bcc23e09eca369) )
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ROM_LOAD( "mon_h.ic25", 0x10000, 0x1000, CRC(10dceac6) SHA1(1ef80039063f7a6455563d59f1bcc23e09eca369) )
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ROM_REGION( 0x800, "chargen", 0 )
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ROM_LOAD( "cg4.rom", 0x000, 0x800, CRC(52e7b9d8) SHA1(cc6d457634eb688ccef471f72bddf0424e64b045) )
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ROM_LOAD( "cg4.ic74", 0x000, 0x800, CRC(52e7b9d8) SHA1(cc6d457634eb688ccef471f72bddf0424e64b045) )
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ROM_REGION( 0x800, "keyboard", 0 )
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ROM_LOAD( "kbd_3.rom", 0x000, 0x800, CRC(d9441b35) SHA1(ce250ab1e892a13fd75182703f259855388c6bf4) )
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ROM_LOAD( "kbd_3.rom", 0x000, 0x800, CRC(d9441b35) SHA1(ce250ab1e892a13fd75182703f259855388c6bf4) )
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ROM_REGION( 0x800, "videoram", ROMREGION_ERASE00 )
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ROM_END
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