bus/bbc/rom: Added support for the Acornsoft Trilogy Emulator board.

src/devices/bus/bbc/rom/pal.cpp

@@ -34,6 +34,12 @@
     Not a PALPROM carrier board but a larger ROM carrier containing 4x32K
     and TTL circuits to enable and page each ROM into 16K banks.
 
+  Acornsoft Trilogy Emulator (PAL20R4)
+    An unreleased product that combines the View family of ROMs into a
+    single banked 64K ROM, using a PAL to perform 16K bank switches upon
+    reads from the last 4 bytes of ROM space &BFFC to &BFFF. Only known
+    example loaned by Stuart Swales.
+
 ***************************************************************************/
 
 #include "emu.h"
@@ -53,6 +59,7 @@ DEFINE_DEVICE_TYPE(BBC_PALTED, bbc_palted_device, "bbc_palted", "Watford Electro
 DEFINE_DEVICE_TYPE(BBC_PALABEP, bbc_palabep_device, "bbc_palabep", "P.R.E.S. 32K ROM Carrier (ABE+)")
 DEFINE_DEVICE_TYPE(BBC_PALABE, bbc_palabe_device, "bbc_palabe", "P.R.E.S. 32K ROM Carrier (ABE)")
 DEFINE_DEVICE_TYPE(BBC_PALMO2, bbc_palmo2_device, "bbc_palmo2", "Instant Mini Office 2 ROM Carrier")
+DEFINE_DEVICE_TYPE(BBC_TRILOGY, bbc_trilogy_device, "bbc_trilogy", "Acornsoft Trilogy Emulator")
 
 
 //**************************************************************************
@@ -115,6 +122,11 @@ bbc_palmo2_device::bbc_palmo2_device(const machine_config &mconfig, const char *
 {
 }
 
+bbc_trilogy_device::bbc_trilogy_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
+	: bbc_pal_device(mconfig, BBC_TRILOGY, tag, owner, clock)
+{
+}
+
 
 //-------------------------------------------------
 //  device_start - device-specific startup
@@ -310,3 +322,17 @@ uint8_t bbc_palmo2_device::read(offs_t offset)
 
 	return get_rom_base()[(offset & 0x3fff) | (m_bank << 13)];
 }
+
+uint8_t bbc_trilogy_device::read(offs_t offset)
+{
+	if (!machine().side_effects_disabled())
+	{
+		/* switching zones for Acornsoft Trilogy Emulator */
+		switch (offset & 0x3ff8)
+		{
+		case 0x3ff8: m_bank = offset & 0x03; break;
+		}
+	}
+
+	return get_rom_base()[(offset & 0x3fff) | (m_bank << 14)];
+}

src/devices/bus/bbc/rom/pal.h

@@ -151,6 +151,19 @@ protected:
 	virtual uint8_t read(offs_t offset) override;
 };
 
+// ======================> bbc_trilogy_device
+
+class bbc_trilogy_device : public bbc_pal_device
+{
+public:
+	// construction/destruction
+	bbc_trilogy_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
+
+protected:
+	// device_bbc_rom_interface overrides
+	virtual uint8_t read(offs_t offset) override;
+};
+
 
 // device type definition
 DECLARE_DEVICE_TYPE(BBC_CCIWORD, bbc_cciword_device)
@@ -162,6 +175,7 @@ DECLARE_DEVICE_TYPE(BBC_PALTED, bbc_palted_device)
 DECLARE_DEVICE_TYPE(BBC_PALABEP, bbc_palabep_device)
 DECLARE_DEVICE_TYPE(BBC_PALABE, bbc_palabe_device)
 DECLARE_DEVICE_TYPE(BBC_PALMO2, bbc_palmo2_device)
+DECLARE_DEVICE_TYPE(BBC_TRILOGY, bbc_trilogy_device)
 
 
 #endif // MAME_BUS_BBC_ROM_PAL_H

src/devices/bus/bbc/rom/slot.cpp

@@ -213,6 +213,7 @@ void bbc_romslot_device::write(offs_t offset, uint8_t data)
 #include "datagem.h"
 #include "dfs.h"
 #include "genie.h"
+//#include "gommc.h"
 #include "pal.h"
 //#include "ramagic.h"
 #include "rtc.h"
@@ -234,8 +235,10 @@ void bbc_rom_devices(device_slot_interface &device)
 	device.option_add_internal("palmo2", BBC_PALMO2);
 	device.option_add_internal("datagem", BBC_DATAGEM);
 	device.option_add_internal("genie", BBC_PMSGENIE);
+	//device.option_add_internal("gommc", BBC_GOMMC);
 	device.option_add_internal("dfse00", BBC_DFSE00);
 	//device.option_add_internal("ramagic", BBC_RAMAGIC);
 	device.option_add_internal("stlrtc",  BBC_STLRTC);
 	device.option_add_internal("pmsrtc", BBC_PMSRTC);
+	device.option_add_internal("trilogy", BBC_TRILOGY);
 }