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bus/a2bus: Made Buffered Grappler+ DRAM size configurable, fixed a bad

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bit in the MCU ROM dump, and marked the MCU ROM as bad.
This commit is contained in:
Vas Crabb 2021-04-04 05:10:59 +10:00
parent 0a424a3ac3
commit d4cc6959af
2 changed files with 44 additions and 11 deletions
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52
src/devices/bus/a2bus/grapplerplus.cpp
View File

@ -1,10 +1,5 @@
// license:BSD-3-Clause
// copyright-holders:Vas Crabb
/*
* TODO for Buffered Grappler+:
* - /RST does not reset the MCU, it’s connected to P27
* - On the schematic, P22 is pulled up, but the program checks it - perhaps a test mode?
*/
#include "emu.h"
#include "grapplerplus.h"
@ -35,7 +30,7 @@ ROM_START(bufgrapplerplus)
ROM_LOAD( "3.2.u18", 0x0000, 0x1000, CRC(cd07c7ef) SHA1(6c2f1375b5df6bb65dfca1444c064661242fef1a) )
ROM_REGION(0x0400, "mcu", 0)
ROM_LOAD( "8048.u10", 0x0000, 0x0400, CRC(f60c14a9) SHA1(e7d87dd2f7af42f0eed776b839dea0a351ab67bc) )
ROM_LOAD( "8048.u10", 0x0000, 0x0400, CRC(36c5e2b2) SHA1(65eea4c7352a93f780df6b30ec6c20ee1e87aa30) BAD_DUMP )
ROM_END
@ -55,6 +50,17 @@ INPUT_PORTS_START(grapplerplus)
PORT_DIPSETTING( 0x00, "Not Transmitted")
INPUT_PORTS_END
INPUT_PORTS_START(bufgrapplerplus)
PORT_INCLUDE(grapplerplus)
PORT_START("CNF")
PORT_CONFNAME(0xff, 0x00, "RAM Size")
PORT_CONFSETTING( 0xfc, "16K (2 chips)")
PORT_CONFSETTING( 0xf0, "32K (4 chips)")
PORT_CONFSETTING( 0x00, "64K (8 chips)")
INPUT_PORTS_END
} // anonymous namespace
@ -480,6 +486,7 @@ a2bus_buf_grapplerplus_device::a2bus_buf_grapplerplus_device(machine_config cons
m_mcu(*this, "mcu"),
m_ram(),
m_ram_row(0xff00),
m_ram_mask(0x00U),
m_mcu_p2(0xffU),
m_data_latch(0xffU),
m_ibusy(1U),
@ -532,6 +539,12 @@ void a2bus_buf_grapplerplus_device::device_add_mconfig(machine_config &config)
}
ioport_constructor a2bus_buf_grapplerplus_device::device_input_ports() const
{
return INPUT_PORTS_NAME(bufgrapplerplus);
}
void a2bus_buf_grapplerplus_device::device_start()
{
a2bus_grapplerplus_device_base::device_start();
@ -540,6 +553,7 @@ void a2bus_buf_grapplerplus_device::device_start()
save_pointer(NAME(m_ram), 0x10000);
save_item(NAME(m_ram_row));
save_item(NAME(m_ram_mask));
save_item(NAME(m_mcu_p2));
save_item(NAME(m_data_latch));
save_item(NAME(m_ibusy));
@ -548,6 +562,25 @@ void a2bus_buf_grapplerplus_device::device_start()
}
void a2bus_buf_grapplerplus_device::device_reset()
{
// The MCU is not reset when /RST is asserted. Instead, /RST is
// connected to P27. Pressing the reset key(s) momentarily will not
// clear the print buffer - the host Apple II can be reset without
// interrupting a long print job. Holding the reset key(s) for two
// seconds clears the buffer. Holding the reset key(s) on initial
// boot enters the RAM test (results are printed). MAME doesn't
// currently cater for devices that don't reset their children on
// reset, and Apple II slots don't currently expose the /RST signal
// directly.
a2bus_grapplerplus_device_base::device_reset();
// should only do this on initial reset, but we get away with it here because the MCU is automatically reset even if it shouldn't be
m_ram_mask = ioport("CNF")->read();
}
//--------------------------------------------------
// a2bus_grapplerplus_device_base implementation
@ -592,9 +625,6 @@ void a2bus_buf_grapplerplus_device::mcu_io(address_map &map)
void a2bus_buf_grapplerplus_device::mcu_p2_w(u8 data)
{
//P22 = pulled up
//P27 = /RST
// check for changed bits
u8 const diff(data ^ m_mcu_p2);
m_mcu_p2 = data;
@ -660,7 +690,7 @@ u8 a2bus_buf_grapplerplus_device::mcu_bus_r()
{
u16 const addr(m_ram_row | u16(m_mcu->p1_r()));
LOG("Read RAM @%04X=%02X\n", addr, m_ram[addr]);
result &= m_ram[addr];
result &= m_ram[addr] | m_ram_mask;
}
else
{
@ -692,7 +722,7 @@ void a2bus_buf_grapplerplus_device::mcu_bus_w(u8 data)
{
u16 const addr(m_ram_row | u16(m_mcu->p1_r()));
LOG("Wrote RAM @%04X=%02X\n", addr, data);
m_ram[addr] = data;
m_ram[addr] = data | m_ram_mask;
}
else
{

3
src/devices/bus/a2bus/grapplerplus.h
View File

@ -167,7 +167,9 @@ protected:
// device_t implementation
virtual tiny_rom_entry const *device_rom_region() const override;
virtual void device_add_mconfig(machine_config &config) override;
virtual ioport_constructor device_input_ports() const override;
virtual void device_start() override;
virtual void device_reset() override;
private:
// a2bus_grapplerplus_device_base implementation
@ -191,6 +193,7 @@ private:
std::unique_ptr<u8 []> m_ram;
u16 m_ram_row; // U1-U8
u8 m_ram_mask; // mask out chips that are not installed
u8 m_mcu_p2; // U10
u8 m_data_latch; // U14 (synchronised)
u8 m_ibusy; // U12