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// license:BSD-3-Clause
// copyright-holders:Ryan Holtz
/*
First-gen DEC PDP-8 CPU emulator
Written by Ryan Holtz
*/
#pragma once
#ifndef __PDP8_H__
#define __PDP8_H__
//**************************************************************************
// TYPE DEFINITIONS
//**************************************************************************
// ======================> pdp8_device
// Used by core CPU interface
class pdp8_device : public cpu_device
{
public:
// construction/destruction
pdp8_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
// device-level overrides
virtual void device_start() override;
virtual void device_reset() override;
virtual void device_stop() override;
// device_execute_interface overrides
virtual uint32_t execute_min_cycles() const override;
virtual uint32_t execute_max_cycles() const override;
virtual uint32_t execute_input_lines() const override;
virtual void execute_run() override;
virtual void execute_set_input(int inputnum, int state) override;
// device_memory_interface overrides
virtual const address_space_config *memory_space_config(address_spacenum spacenum = AS_0) const override;
// device_disasm_interface overrides
virtual uint32_t disasm_min_opcode_bytes() const override;
virtual uint32_t disasm_max_opcode_bytes() const override;
virtual offs_t disasm_disassemble(char *buffer, offs_t pc, const uint8_t *oprom, const uint8_t *opram, uint32_t options) override;
// device_state_interface overrides
virtual void state_string_export(const device_state_entry &entry, std::string &str) const override;
// address spaces
const address_space_config m_program_config;
enum state
{
FETCH,
DEFER,
EXECUTE,
WORD_COUNT,
CURRENT_ADDR,
BREAK
};
enum opcode
{
AND = 0,
TAD,
ISZ,
DCA,
JMS,
JMP,
IOT,
OPR
};
private:
// CPU registers
uint16_t m_pc;
uint16_t m_ac;
uint16_t m_mb;
uint16_t m_ma;
uint16_t m_sr;
uint8_t m_l;
uint8_t m_ir;
bool m_halt;
// other internal states
int m_icount;
// address spaces
address_space *m_program;
};
// device type definition
extern const device_type PDP8CPU;
/***************************************************************************
REGISTER ENUMERATION
***************************************************************************/
enum
{
PDP8_PC = 1,
PDP8_AC,
PDP8_MB,
PDP8_MA,
PDP8_SR,
PDP8_L,
PDP8_IR,
PDP8_HALT
};
CPU_DISASSEMBLE( pdp8 );
#endif /* __PDP8_H__ */
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