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author hap <happppp@users.noreply.github.com>2019-03-12 16:35:42 +0100
committer hap <happppp@users.noreply.github.com>2019-03-12 16:36:00 +0100
commit7fa6825e45c63021378275317758d3e5f4b8ab12 (patch)
tree671283810cc165a946f9591d430b4813ad7f8d5e
parent16f19a2a74884db7a2763dc163b5658cf8f07589 (diff)
f3853: add notes (nw)
-rw-r--r--src/devices/machine/f3853.cpp110
-rw-r--r--src/devices/machine/f3853.h96
-rw-r--r--src/mame/drivers/gamemachine.cpp7
3 files changed, 128 insertions, 85 deletions
diff --git a/src/devices/machine/f3853.cpp b/src/devices/machine/f3853.cpp
index ef08b087d5c..b8fd94f9d1d 100644
--- a/src/devices/machine/f3853.cpp
+++ b/src/devices/machine/f3853.cpp
@@ -2,37 +2,45 @@
// copyright-holders:Wilbert Pol, hap
/**********************************************************************
-Fairchild F3853 SRAM interface with integrated interrupt
-controller and timer (SMI)
+Fairchild F3853 SMI, F3851 PSU, F3856 PSU, F38T56 PSU
-This chip is a timer shift register, basically the same as in the
-F3851.
+This device only emulates the I/O, interrupt, timer functions. Not the
+low-level ROMC signals.
-Based on a datasheet obtained from www.freetradezone.com
+F3853: Static memory interface with integrated interrupt controller and timer.
-8-bit shift register:
+The timer is a shift register:
Feedback in0 = !((out3 ^ out4) ^ (out5 ^ out7))
Interrupts are at 0xfe
0xff stops the register (0xfe is never reached)
+F3851: Program Storage Unit, same timer and interrupt controller as F3853,
+but has 2 I/O ports instead of a programmable interrupt vector.
+
+F3856/F38T56 Program Storage Unit: similar interrupt controller, timer
+is more versatile, a simple downcounter instead of shift register.
+
+TODO:
+- emulate at lower level and place this stuff into devices/cpu/f8 folder
+- interrupt priority pin
+- 3856/38T56 timer pulse counter mode, event counter mode
+
**********************************************************************/
#include "emu.h"
#include "f3853.h"
-//**************************************************************************
-// LIVE DEVICE
-//**************************************************************************
-
// device type definition
-DEFINE_DEVICE_TYPE(F3853, f3853_device, "f3853_device", "F3853 SMI")
-DEFINE_DEVICE_TYPE(F3851, f3851_device, "f3851_device", "F3851 PSU")
-DEFINE_DEVICE_TYPE(F3856, f3856_device, "f3856_device", "F3856 PSU")
-DEFINE_DEVICE_TYPE(F38T56, f38t56_device, "f38t56_device", "F38T56 PSU")
+
+DEFINE_DEVICE_TYPE(F3853, f3853_device, "f3853_smi", "Fairchild F3853 SMI")
+DEFINE_DEVICE_TYPE(F3851, f3851_device, "f3851_psu", "Fairchild F3851 PSU")
+DEFINE_DEVICE_TYPE(F3856, f3856_device, "f3856_psu", "Fairchild F3856 PSU")
+DEFINE_DEVICE_TYPE(F38T56, f38t56_device, "f38t56_psu", "Fairchild F38T56 PSU")
+
//-------------------------------------------------
-// f3853_device - constructor
+// constructor
//-------------------------------------------------
f3853_device::f3853_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock) :
@@ -72,6 +80,11 @@ f38t56_device::f38t56_device(const machine_config &mconfig, const char *tag, dev
{ }
+
+//-------------------------------------------------
+// initialisation
+//-------------------------------------------------
+
void f3853_device::device_resolve_objects()
{
m_int_req_callback.resolve_safe();
@@ -90,11 +103,6 @@ void f3851_device::device_resolve_objects()
cb.resolve_safe();
}
-
-//-------------------------------------------------
-// device_start - device-specific startup
-//-------------------------------------------------
-
void f3853_device::device_start()
{
// lookup table for 3851/3853 lfsr timer
@@ -108,15 +116,15 @@ void f3853_device::device_start()
m_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(f3853_device::timer_callback),this));
// zerofill (what's not in constructor)
- m_external_enable = false;
- m_timer_enable = false;
+ m_external_int_enable = false;
+ m_timer_int_enable = false;
m_request_flipflop = false;
// register for savestates
save_item(NAME(m_int_vector));
save_item(NAME(m_prescaler));
- save_item(NAME(m_external_enable));
- save_item(NAME(m_timer_enable));
+ save_item(NAME(m_external_int_enable));
+ save_item(NAME(m_timer_int_enable));
save_item(NAME(m_request_flipflop));
save_item(NAME(m_priority_line));
save_item(NAME(m_external_interrupt_line));
@@ -135,33 +143,34 @@ void f3856_device::device_start()
save_item(NAME(m_timer_start));
}
-//-------------------------------------------------
-// device_reset - device-specific reset
-//-------------------------------------------------
-
void f3853_device::device_reset()
{
- // clear ports
+ // note that standalone peripherals don't have a reset pin, but 3870 does
+
+ // clear ports at power-on
for (int i = 0; i < 4; i++)
write(machine().dummy_space(), i, 0);
}
+//-------------------------------------------------
+// implementation
+//-------------------------------------------------
+
void f3853_device::set_interrupt_request_line()
{
m_int_req_callback(m_request_flipflop && !m_priority_line ? ASSERT_LINE : CLEAR_LINE);
}
-
IRQ_CALLBACK_MEMBER(f3853_device::int_acknowledge)
{
- if (m_external_enable && !m_priority_line && m_request_flipflop)
+ if (m_external_int_enable && !m_priority_line && m_request_flipflop)
{
m_request_flipflop = false;
set_interrupt_request_line();
return external_interrupt_vector();
}
- else if (m_timer_enable && !m_priority_line && m_request_flipflop)
+ else if (m_timer_int_enable && !m_priority_line && m_request_flipflop)
{
m_request_flipflop = false;
set_interrupt_request_line();
@@ -187,7 +196,7 @@ void f3853_device::timer_start(uint8_t value)
TIMER_CALLBACK_MEMBER(f3853_device::timer_callback)
{
- if(m_timer_enable)
+ if(m_timer_int_enable)
{
m_request_flipflop = true;
set_interrupt_request_line();
@@ -195,9 +204,10 @@ TIMER_CALLBACK_MEMBER(f3853_device::timer_callback)
timer_start(0xfe);
}
+
WRITE_LINE_MEMBER(f3853_device::ext_int_w)
{
- if(m_external_interrupt_line && !state && m_external_enable)
+ if(m_external_interrupt_line && !state && m_external_int_enable)
{
m_request_flipflop = true;
}
@@ -242,8 +252,8 @@ WRITE8_MEMBER(f3853_device::write)
// interrupt control
case 2:
- m_external_enable = (data & 3) == 1;
- m_timer_enable = (data & 3) == 3;
+ m_external_int_enable = (data & 3) == 1;
+ m_timer_int_enable = (data & 3) == 3;
set_interrupt_request_line();
break;
@@ -257,6 +267,10 @@ WRITE8_MEMBER(f3853_device::write)
}
+//-------------------------------------------------
+// f3851_device-specific handlers
+//-------------------------------------------------
+
READ8_MEMBER(f3851_device::read)
{
switch (offset & 3)
@@ -288,6 +302,10 @@ WRITE8_MEMBER(f3851_device::write)
}
+//-------------------------------------------------
+// f3856_device-specific handlers
+//-------------------------------------------------
+
void f3856_device::timer_start(uint8_t value)
{
m_timer_count = value;
@@ -301,7 +319,7 @@ TIMER_CALLBACK_MEMBER(f3856_device::timer_callback)
if (--m_timer_count == 0)
{
m_timer_count = m_timer_modulo;
- if (m_timer_enable)
+ if (m_timer_int_enable)
{
m_request_flipflop = true;
set_interrupt_request_line();
@@ -334,7 +352,7 @@ WRITE8_MEMBER(f3856_device::write)
f3851_device::write(space, offset, data);
break;
- // interrupt control
+ // interrupt/timer control
case 2:
{
// timer prescaler
@@ -348,8 +366,8 @@ WRITE8_MEMBER(f3856_device::write)
timer_start(m_timer_count);
// enable interrupts
- m_external_enable = (data & 3) == 1 || (data & 3) == 2;
- m_timer_enable = bool(data & 2);
+ m_external_int_enable = (data & 3) == 1 || (data & 3) == 2;
+ m_timer_int_enable = bool(data & 2);
set_interrupt_request_line();
break;
}
@@ -362,16 +380,20 @@ WRITE8_MEMBER(f3856_device::write)
}
+//-------------------------------------------------
+// f38t56_device-specific handlers
+//-------------------------------------------------
+
WRITE8_MEMBER(f38t56_device::write)
{
switch (offset & 3)
{
// I/O ports: same as 3851
- default:
+ case 0: case 1:
f3851_device::write(space, offset, data);
break;
- // interrupt control
+ // interrupt/timer control
case 2:
{
// timer prescaler
@@ -387,8 +409,8 @@ WRITE8_MEMBER(f38t56_device::write)
timer_start(m_timer_count);
// enable interrupts
- m_external_enable = bool(data & 1);
- m_timer_enable = bool(data & 2);
+ m_external_int_enable = bool(data & 1);
+ m_timer_int_enable = bool(data & 2);
set_interrupt_request_line();
break;
}
diff --git a/src/devices/machine/f3853.h b/src/devices/machine/f3853.h
index 523864dd9f8..b880f56e9bc 100644
--- a/src/devices/machine/f3853.h
+++ b/src/devices/machine/f3853.h
@@ -1,49 +1,67 @@
// license:BSD-3-Clause
// copyright-holders:Wilbert Pol, hap
-/***************************************************************************
-
- Fairchild F3853 SRAM interface with integrated interrupt
- controller and timer
-
- This chip is a timer shift register, basically the same as in the
- F3851.
-
-****************************************************************************
- _____ _____
- Vgg 1 |* \_/ | 40 Vdd
- PHI 2 | | 39 ROMC4
- WRITE 3 | | 38 ROMC3
- _INT REQ 4 | | 37 ROMC2
- _PRI IN 5 | | 36 ROMC1
- _RAM WRITE 6 | | 35 ROMC0
- _EXT INT 7 | | 34 CPU READ
- ADDR7 8 | | 33 REG DR
- ADDR6 9 | | 32 ADDR15
- ADDR5 10 | F3853 | 31 ADDR14
- ADDR4 11 | | 30 ADDR13
- ADDR3 12 | | 29 ADDR12
- ADDR2 13 | | 28 ADDR11
- ADDR1 14 | | 27 ADDR10
- ADDR0 15 | | 26 ADDR9
- DB0 16 | | 25 ADDR8
- DB1 17 | | 24 DB7
- DB2 18 | | 23 DB6
- DB3 19 | | 22 DB5
- Vss 20 |_____________| 21 DB4
-
-***************************************************************************/
+/*
+
+ Fairchild F3853 SMI, F3851 PSU, F3856 PSU, F38T56 PSU
+
+*/
#ifndef MAME_MACHINE_F3853_H
#define MAME_MACHINE_F3853_H
#pragma once
+// pinout reference
+
+/*
+ _____ _____
+ Vgg 1 |* \_/ | 40 Vdd
+ PHI 2 | | 39 ROMC4
+ WRITE 3 | | 38 ROMC3
+ _INT REQ 4 | | 37 ROMC2
+ _PRI IN 5 | | 36 ROMC1
+ _RAM WRITE 6 | | 35 ROMC0
+ _EXT INT 7 | | 34 CPU READ
+ ADDR7 8 | | 33 REG DR
+ ADDR6 9 | | 32 ADDR15
+ ADDR5 10 | F3853 | 31 ADDR14
+ ADDR4 11 | | 30 ADDR13
+ ADDR3 12 | | 29 ADDR12
+ ADDR2 13 | | 28 ADDR11
+ ADDR1 14 | | 27 ADDR10
+ ADDR0 15 | | 26 ADDR9
+ DB0 16 | | 25 ADDR8
+ DB1 17 | | 24 DB7
+ DB2 18 | | 23 DB6
+ DB3 19 | | 22 DB5
+ Vss 20 |_____________| 21 DB4
+
+ _____ _____
+ _I/O B7 1 |* \_/ | 40 DB7
+ _I/O A7 2 | | 39 DB6
+ Vgg 3 | | 38 _I/O B6
+ Vdd 4 | | 37 _I/O A6
+ _EXT INT 5 | | 36 _I/O A5
+ _PRI OUT 6 | | 35 _I/O B5
+ WRITE 7 | | 34 DB5
+ PHI 8 | | 33 DB4
+ _INT REQ 9 | F3851 | 32 _I/O B4
+ _PRI IN 10 | F3856 | 31 _I/O A4
+ _DBDR 11 | F38T56 | 30 _I/O A3
+ STROBE 12 | | 29 _I/O B3
+ ROMC4 13 | | 28 DB3
+ ROMC3 14 | | 27 DB2
+ ROMC2 15 | | 26 _I/O B2
+ ROMC1 16 | | 25 _I/O A2
+ ROMC0 17 | | 24 _I/O A1
+ Vss 18 | | 23 _I/O B1
+ _I/O A0 19 | | 22 DB1
+ _I/O B0 20 |_____________| 21 DB0
+
+ F38T56 is internal in F3870
+ note: STROBE is N/C on F3851
+*/
-/***************************************************************************
- TYPE DEFINITIONS
-***************************************************************************/
-
-// ======================> f3853_device
class f3853_device : public device_t
{
@@ -85,8 +103,8 @@ protected:
uint16_t m_int_vector; // Bit 7 is set to 0 for timer interrupts, 1 for external interrupts
u8 m_prescaler;
- bool m_external_enable;
- bool m_timer_enable;
+ bool m_external_int_enable;
+ bool m_timer_int_enable;
bool m_request_flipflop;
diff --git a/src/mame/drivers/gamemachine.cpp b/src/mame/drivers/gamemachine.cpp
index 75f0a6ae379..5b714e1dd77 100644
--- a/src/mame/drivers/gamemachine.cpp
+++ b/src/mame/drivers/gamemachine.cpp
@@ -28,6 +28,9 @@ hardware notes:
TODO:
- discrete sound, currently it's emulated crudely, just enough to make it beep when supposed to
+- MCU frequency was measured approx 2.1MHz on its XTL2 pin, but considering that
+ the MK3870 has an internal /2 divider, this is way too slow when compared to
+ video references of the game
******************************************************************************/
@@ -265,11 +268,11 @@ INPUT_PORTS_END
void tgm_state::tgm(machine_config &config)
{
/* basic machine hardware */
- F8(config, m_maincpu, 2000000); // MK3870, measured around 2.1MHz
+ F8(config, m_maincpu, 4000000/2); // MK3870, frequency is approximate
m_maincpu->set_addrmap(AS_PROGRAM, &tgm_state::main_map);
m_maincpu->set_addrmap(AS_IO, &tgm_state::main_io);
- f38t56_device &psu(F38T56(config, "psu", 2000000));
+ f38t56_device &psu(F38T56(config, "psu", 4000000/2));
psu.write_a().set(FUNC(tgm_state::sound_w));
psu.write_b().set(FUNC(tgm_state::digit_w));