summaryrefslogtreecommitdiffstatshomepage
path: root/src/devices/machine/f3853.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'src/devices/machine/f3853.cpp')
-rw-r--r--src/devices/machine/f3853.cpp353
1 files changed, 284 insertions, 69 deletions
diff --git a/src/devices/machine/f3853.cpp b/src/devices/machine/f3853.cpp
index f4713f3fa3a..45511f334ab 100644
--- a/src/devices/machine/f3853.cpp
+++ b/src/devices/machine/f3853.cpp
@@ -1,19 +1,29 @@
// license:BSD-3-Clause
-// copyright-holders:Wilbert Pol
+// 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:
- Feedback in0 = !((out3 ^ out4) ^ (out5 ^ out7))
- Interrupts are at 0xfe
- 0xff stops the register (0xfe is never reached)
+The timer is an 8-bit linear feedback 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
**********************************************************************/
@@ -21,30 +31,59 @@
#include "f3853.h"
+// device type definition
-/***************************************************************************
- IMPLEMENTATION
-***************************************************************************/
-
-//**************************************************************************
-// LIVE DEVICE
-//**************************************************************************
+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")
-// device type definition
-DEFINE_DEVICE_TYPE(F3853, f3853_device, "f3853_device", "F3853 SMI")
//-------------------------------------------------
-// f3853_device - constructor
+// constructor
//-------------------------------------------------
-f3853_device::f3853_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
- : device_t(mconfig, F3853, tag, owner, clock)
- , m_int_req_callback(*this)
- , m_pri_out_callback(*this)
- , m_priority_line(false)
- , m_external_interrupt_line(true)
-{
-}
+f3853_device::f3853_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock) :
+ device_t(mconfig, type, tag, owner, clock),
+ m_int_req_callback(*this),
+ m_pri_out_callback(*this),
+ m_int_vector(0),
+ m_prescaler(31),
+ m_priority_line(false),
+ m_external_interrupt_line(true)
+{ }
+
+f3853_device::f3853_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) :
+ f3853_device(mconfig, F3853, tag, owner, clock)
+{ }
+
+f3851_device::f3851_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock) :
+ f3853_device(mconfig, type, tag, owner, clock),
+ m_read_port{{*this}, {*this}},
+ m_write_port{{*this}, {*this}}
+{ }
+
+f3851_device::f3851_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) :
+ f3851_device(mconfig, F3851, tag, owner, clock)
+{ }
+
+f3856_device::f3856_device(const machine_config &mconfig, device_type type, const char *tag, device_t *owner, u32 clock) :
+ f3851_device(mconfig, type, tag, owner, clock)
+{ }
+
+f3856_device::f3856_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) :
+ f3856_device(mconfig, F3856, tag, owner, clock)
+{ }
+
+f38t56_device::f38t56_device(const machine_config &mconfig, const char *tag, device_t *owner, u32 clock) :
+ f3856_device(mconfig, F38T56, tag, owner, clock)
+{ }
+
+
+
+//-------------------------------------------------
+// initialisation
+//-------------------------------------------------
void f3853_device::device_resolve_objects()
{
@@ -53,12 +92,20 @@ void f3853_device::device_resolve_objects()
m_int_daisy_chain_callback.bind_relative_to(*owner());
}
-//-------------------------------------------------
-// device_start - device-specific startup
-//-------------------------------------------------
+void f3851_device::device_resolve_objects()
+{
+ f3853_device::device_resolve_objects();
+
+ // 2 I/O ports
+ for (devcb_read8 &cb : m_read_port)
+ cb.resolve_safe(0);
+ for (devcb_write8 &cb : m_write_port)
+ cb.resolve_safe();
+}
void f3853_device::device_start()
{
+ // lookup table for 3851/3853 lfsr timer
uint8_t reg = 0xfe; // Known to get 0xfe after 255 cycles
for(int i = reg; i >= 0; i--)
{
@@ -68,47 +115,62 @@ 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_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_external_enable));
- save_item(NAME(m_timer_enable));
+ save_item(NAME(m_prescaler));
+ 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));
}
+void f3856_device::device_start()
+{
+ f3853_device::device_start();
-//-------------------------------------------------
-// device_reset - device-specific reset
-//-------------------------------------------------
+ m_timer_count = 0;
+ m_timer_modulo = 0;
+ m_timer_start = false;
+
+ save_item(NAME(m_timer_count));
+ save_item(NAME(m_timer_modulo));
+ save_item(NAME(m_timer_start));
+}
void f3853_device::device_reset()
{
- m_int_vector = 0;
- m_external_enable = false;
- m_timer_enable = false;
- m_request_flipflop = false;
- m_external_interrupt_line = true;
- set_interrupt_request_line();
+ // note that standalone peripherals don't have a reset pin, but 3870 does
- m_timer->enable(false);
+ // 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();
@@ -127,14 +189,14 @@ IRQ_CALLBACK_MEMBER(f3853_device::int_acknowledge)
void f3853_device::timer_start(uint8_t value)
{
- attotime period = (value != 0xff) ? attotime::from_hz(clock()) * (m_value_to_cycle[value]*31) : attotime::never;
+ attotime period = (value != 0xff) ? attotime::from_hz(clock()) * (m_value_to_cycle[value] * m_prescaler) : attotime::never;
m_timer->adjust(period);
}
TIMER_CALLBACK_MEMBER(f3853_device::timer_callback)
{
- if(m_timer_enable)
+ if(m_timer_int_enable)
{
m_request_flipflop = true;
set_interrupt_request_line();
@@ -142,9 +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;
}
@@ -161,49 +224,201 @@ WRITE_LINE_MEMBER(f3853_device::pri_in_w)
READ8_MEMBER(f3853_device::read)
{
- uint8_t data = 0;
-
- switch (offset)
+ switch (offset & 3)
{
+ // interrupt vector
case 0:
- data = m_int_vector >> 8;
- break;
-
+ return m_int_vector >> 8;
case 1:
- data = m_int_vector & 0xff;
- break;
+ return m_int_vector & 0xff;
- case 2: // Interrupt control; not readable
- case 3: // Timer; not readable
- break;
+ // interrupt control, timer: write-only
+ default:
+ return 0;
}
-
- return data;
}
-
WRITE8_MEMBER(f3853_device::write)
{
- switch(offset)
+ switch (offset & 3)
{
+ // interrupt vector
case 0:
m_int_vector = (data << 8) | (m_int_vector & 0x00ff);
break;
-
case 1:
m_int_vector = data | (m_int_vector & 0xff00);
break;
- case 2: //interrupt control
- m_external_enable = ((data & 3) == 1);
- m_timer_enable = ((data & 3) == 3);
+ // interrupt control
+ case 2:
+ m_external_int_enable = (data & 3) == 1;
+ m_timer_int_enable = (data & 3) == 3;
set_interrupt_request_line();
break;
- case 3: //timer
+ // set timer
+ case 3:
m_request_flipflop = false;
set_interrupt_request_line();
timer_start(data);
break;
}
}
+
+
+//-------------------------------------------------
+// f3851_device-specific handlers
+//-------------------------------------------------
+
+READ8_MEMBER(f3851_device::read)
+{
+ switch (offset & 3)
+ {
+ // I/O ports
+ case 0: case 1:
+ return (m_read_port[offset & 1])(offs_t(offset & 1));
+
+ // interrupt control, timer: write-only
+ default:
+ return 0;
+ }
+}
+
+WRITE8_MEMBER(f3851_device::write)
+{
+ switch (offset & 3)
+ {
+ // I/O ports
+ case 0: case 1:
+ (m_write_port[offset & 1])(offs_t(offset & 1), data);
+ break;
+
+ // interrupt control, timer: same as 3853
+ case 2: case 3:
+ f3853_device::write(space, offset, data);
+ break;
+ }
+}
+
+
+//-------------------------------------------------
+// f3856_device-specific handlers
+//-------------------------------------------------
+
+void f3856_device::timer_start(uint8_t value)
+{
+ m_timer_count = value;
+ attotime period = (m_timer_start) ? (attotime::from_hz(clock()) * m_prescaler) : attotime::never;
+
+ m_timer->adjust(period);
+}
+
+TIMER_CALLBACK_MEMBER(f3856_device::timer_callback)
+{
+ if (--m_timer_count == 0)
+ {
+ m_timer_count = m_timer_modulo;
+ if (m_timer_int_enable)
+ {
+ m_request_flipflop = true;
+ set_interrupt_request_line();
+ }
+ }
+
+ timer_start(m_timer_count);
+}
+
+READ8_MEMBER(f3856_device::read)
+{
+ switch (offset & 3)
+ {
+ // timer: active counter
+ case 3:
+ return m_timer_count;
+
+ // other: same as 3851
+ default:
+ return f3851_device::read(space, offset);
+ }
+}
+
+WRITE8_MEMBER(f3856_device::write)
+{
+ switch (offset & 3)
+ {
+ // I/O ports: same as 3851
+ case 0: case 1:
+ f3851_device::write(space, offset, data);
+ break;
+
+ // interrupt/timer control
+ case 2:
+ {
+ // timer prescaler
+ static const u8 prescaler[8] = { 32, 128, 8, 2 };
+ m_prescaler = prescaler[data >> 5 & 7];
+
+ // start/stop timer
+ bool prev = m_timer_start;
+ m_timer_start = bool(~data & 0x10);
+ if (m_timer_start != prev)
+ timer_start(m_timer_count);
+
+ // enable interrupts
+ m_external_int_enable = (data & 3) == 1 || (data & 3) == 2;
+ m_timer_int_enable = bool(data & 2);
+ set_interrupt_request_line();
+ break;
+ }
+
+ // set timer
+ case 3:
+ f3853_device::write(space, offset, data);
+ break;
+ }
+}
+
+
+//-------------------------------------------------
+// f38t56_device-specific handlers
+//-------------------------------------------------
+
+WRITE8_MEMBER(f38t56_device::write)
+{
+ switch (offset & 3)
+ {
+ // I/O ports: same as 3851
+ case 0: case 1:
+ f3851_device::write(space, offset, data);
+ break;
+
+ // interrupt/timer control
+ case 2:
+ {
+ // timer prescaler
+ m_prescaler = 200;
+ if (~data & 0x80) m_prescaler /= 20;
+ if (~data & 0x40) m_prescaler /= 5;
+ if (~data & 0x20) m_prescaler /= 2;
+
+ // start/stop timer
+ bool prev = m_timer_start;
+ m_timer_start = bool(data & 8);
+ if (m_timer_start != prev)
+ timer_start(m_timer_count);
+
+ // enable interrupts
+ m_external_int_enable = bool(data & 1);
+ m_timer_int_enable = bool(data & 2);
+ set_interrupt_request_line();
+ break;
+ }
+
+ // set timer
+ case 3:
+ m_timer_modulo = data;
+ f3853_device::write(space, offset, data);
+ break;
+ }
+}