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Diffstat (limited to 'src/mess/machine/a2scsi.c')
-rw-r--r-- | src/mess/machine/a2scsi.c | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/src/mess/machine/a2scsi.c b/src/mess/machine/a2scsi.c new file mode 100644 index 00000000000..111d165214a --- /dev/null +++ b/src/mess/machine/a2scsi.c @@ -0,0 +1,249 @@ +/********************************************************************* + + a2scsi.c + + Implementation of the Apple II SCSI Card + + Schematic at: + http://mirrors.apple2.org.za/Apple%20II%20Documentation%20Project/Interface%20Cards/SCSI%20Controllers/Apple%20II%20SCSI%20Card/Schematics/Rev.%20C%20SCSI%20Schematic%20-%20Updated%202-23-6.jpg + + + Notes: + + C0n0-C0n7 = NCR5380 registers in normal order + C0n9 = DIP switches + C0na = RAM and ROM bank switching + C0nb = reset 5380 + C0ne = into the PAL stuff + +*********************************************************************/ + +#include "a2scsi.h" +#include "includes/apple2.h" + + +/*************************************************************************** + PARAMETERS +***************************************************************************/ + +//************************************************************************** +// GLOBAL VARIABLES +//************************************************************************** + +const device_type A2BUS_SCSI = &device_creator<a2bus_scsi_device>; + +#define SCSI_ROM_REGION "scsi_rom" +#define SCSI_5380_TAG "ncr5380" + +static const SCSIConfigTable dev_table = +{ + 0, /* 2 SCSI devices */ + { +// { SCSI_ID_6, "harddisk1", SCSI_DEVICE_HARDDISK }, /* SCSI ID 6, using disk1, and it's a harddisk */ +// { SCSI_ID_5, "harddisk2", SCSI_DEVICE_HARDDISK } /* SCSI ID 5, using disk2, and it's a harddisk */ + } +}; + +static const struct NCR5380interface a2scsi_5380_intf = +{ + &dev_table, // SCSI device table + NULL // IRQ handler (unconnected according to schematic) +}; + +MACHINE_CONFIG_FRAGMENT( scsi ) + MCFG_NCR5380_ADD(SCSI_5380_TAG, (XTAL_28_63636MHz/4), a2scsi_5380_intf) +MACHINE_CONFIG_END + +ROM_START( scsi ) + ROM_REGION(0x4000, SCSI_ROM_REGION, 0) // this is the Rev. C ROM + ROM_LOAD( "341-0437-a.bin", 0x0000, 0x4000, CRC(5aff85d3) SHA1(451c85c46b92e6ad2ad930f055ccf0fe3049936d) ) +ROM_END + +/*************************************************************************** + FUNCTION PROTOTYPES +***************************************************************************/ + +//------------------------------------------------- +// machine_config_additions - device-specific +// machine configurations +//------------------------------------------------- + +machine_config_constructor a2bus_scsi_device::device_mconfig_additions() const +{ + return MACHINE_CONFIG_NAME( scsi ); +} + +//------------------------------------------------- +// rom_region - device-specific ROM region +//------------------------------------------------- + +const rom_entry *a2bus_scsi_device::device_rom_region() const +{ + return ROM_NAME( scsi ); +} + +//************************************************************************** +// LIVE DEVICE +//************************************************************************** + +a2bus_scsi_device::a2bus_scsi_device(const machine_config &mconfig, device_type type, const char *name, const char *tag, device_t *owner, UINT32 clock) : + device_t(mconfig, type, name, tag, owner, clock), + device_a2bus_card_interface(mconfig, *this), + m_ncr5380(*this, SCSI_5380_TAG) +{ + m_shortname = "a2scsi"; +} + +a2bus_scsi_device::a2bus_scsi_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) : + device_t(mconfig, A2BUS_SCSI, "Apple II SCSI Card", tag, owner, clock), + device_a2bus_card_interface(mconfig, *this), + m_ncr5380(*this, SCSI_5380_TAG) +{ + m_shortname = "a2scsi"; +} + +//------------------------------------------------- +// device_start - device-specific startup +//------------------------------------------------- + +void a2bus_scsi_device::device_start() +{ + // set_a2bus_device makes m_slot valid + set_a2bus_device(); + + astring tempstring; + m_rom = device().machine().root_device().memregion(this->subtag(tempstring, SCSI_ROM_REGION))->base(); + + memset(m_ram, 0, 8192); + + save_item(NAME(m_ram)); + save_item(NAME(m_rambank)); + save_item(NAME(m_rombank)); +} + +void a2bus_scsi_device::device_reset() +{ + m_rambank = m_rombank = 0; // CLR on 74LS273 at U3E is connected to RES, so these clear on reset +} + + +/*------------------------------------------------- + read_c0nx - called for reads from this card's c0nx space +-------------------------------------------------*/ + +UINT8 a2bus_scsi_device::read_c0nx(address_space &space, UINT8 offset) +{ + printf("Read c0n%x (PC=%x)\n", offset, cpu_get_pc(&space.device())); + + switch (offset) + { + case 0: + case 1: + case 2: + case 3: + case 4: + case 5: + case 6: + case 7: + return ncr5380_read_reg(m_ncr5380, offset); + + case 9: // card's ID? + return 7; + } + + return 0xff; +} + + +/*------------------------------------------------- + write_c0nx - called for writes to this card's c0nx space +-------------------------------------------------*/ + +void a2bus_scsi_device::write_c0nx(address_space &space, UINT8 offset, UINT8 data) +{ + printf("Write %02x to c0n%x (PC=%x)\n", data, offset, cpu_get_pc(&space.device())); + + switch (offset) + { + case 0: + case 1: + case 2: + case 3: + case 4: + case 5: + case 6: + case 7: + ncr5380_write_reg(m_ncr5380, offset, data); + break; + + case 0xa: // ROM and RAM banking (74LS273 at U3E) + /* + ROM banking: + (bits EA8-EA13 are all zeroed when /IOSEL is asserted, so CnXX always gets the first page of the ROM) + EA10 = bit 0 + EA11 = bit 1 + EA12 = bit 2 + EA13 = bit 3 (N/C) + + RAM banking: + RA10 = bit 4 + RA11 = bit 5 + RA12 = bit 6 + */ + + m_rambank = ((data>>4) & 0x7) * 0x400; + m_rombank = (data & 0xf) * 0x400; + printf("RAM bank to %x, ROM bank to %x\n", m_rambank, m_rombank); + break; + + case 0xb: + printf("Reset NCR5380\n"); + break; + } +} + +/*------------------------------------------------- + read_cnxx - called for reads from this card's cnxx space +-------------------------------------------------*/ + +UINT8 a2bus_scsi_device::read_cnxx(address_space &space, UINT8 offset) +{ + // one slot image at the start of the ROM, it appears + return m_rom[offset]; +} + +void a2bus_scsi_device::write_cnxx(address_space &space, UINT8 offset, UINT8 data) +{ + printf("Write %02x to cn%02x (PC=%x)\n", data, offset, cpu_get_pc(&space.device())); +} + +/*------------------------------------------------- + read_c800 - called for reads from this card's c800 space +-------------------------------------------------*/ + +UINT8 a2bus_scsi_device::read_c800(address_space &space, UINT16 offset) +{ + // bankswitched RAM at c800-cbff + // bankswitched ROM at cc00-cfff + if (offset < 0x400) + { + printf("Read RAM at %x = %02x\n", offset+m_rambank, m_ram[offset + m_rambank]); + return m_ram[offset + m_rambank]; + } + else + { + return m_rom[(offset-0x400) + m_rombank]; + } +} + +/*------------------------------------------------- + write_c800 - called for writes to this card's c800 space +-------------------------------------------------*/ +void a2bus_scsi_device::write_c800(address_space &space, UINT16 offset, UINT8 data) +{ + if (offset < 0x400) + { + printf("%02x to RAM at %x\n", data, offset+m_rambank); + m_ram[offset + m_rambank] = data; + } +} |