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## Hard wired locations of the control signals
SIG_REG_A_OUT = 0x1
SIG_ALU_OUT = 0x2
SIG_REG_B_OUT = 0x4
SIG_PC_OUT = 0x8
SIG_PC_TICK = 0x10
SIG_PC_LOAD = 0x20
SIG_ALU_SUB = 0x40
SIG_MEM_ENABLE = 0x80
SIG_MEM_DIR_OUT = 0x100
SIG_INST_OUT = 0x200
SIG_INST_IN = 0x400
SIG_MEM_ADDRESS_IN = 0x800
SIG_REG_A_IN = 0x1000
SIG_REG_B_IN = 0x2000
SIG_HEX_OUT = 0x4000
## Define control word for common micro instructions
MICRO_INST_MEM_TO_REG_A = SIG_REG_A_IN | SIG_MEM_DIR_OUT | SIG_MEM_ENABLE
MICRO_INST_MEM_TO_REG_B = SIG_REG_B_IN | SIG_MEM_DIR_OUT | SIG_MEM_ENABLE
MICRO_INST_PC_TO_REG_MEM_ADDRESS = SIG_MEM_ADDRESS_IN | SIG_PC_OUT
MICRO_INST_MEM_TO_INST = SIG_INST_IN | SIG_MEM_DIR_OUT | SIG_MEM_ENABLE
## max number of micro instructions a macro instruction can have
MAX_MICRO_OPS = 6
## the last four bits of this OP is loaded into the REG A
INST_LDA = 0x10
INST_MICRO_OP_LDA = [SIG_INST_OUT | SIG_REG_A_IN]
## the last four bits of this OP is loaded into the REG B
INST_LDB = 0x20
INST_MICRO_OP_LDB = [SIG_INST_OUT | SIG_REG_B_IN]
## this instruction show the content of REG A on the 7hex display
INST_REG_A_OUT = 0x30
INST_MICRO_OP_REG_A_OUT = [SIG_REG_A_OUT | SIG_HEX_OUT]
## this instruction show the content of REG B on the 7hex display
INST_REG_B_OUT = 0x40
INST_MICRO_OP_REG_B_OUT = [SIG_REG_B_OUT | SIG_HEX_OUT]
## this instruction adds the content of REG_A and REG_B and saves the result in
## REG_A
INST_ADD_A = 0x50
INST_MICRO_OP_ADD_A = [SIG_ALU_OUT | SIG_REG_A_IN]
## this instruction adds the content of REG_A and REG_B and saves the result in
## REG_B
INST_ADD_B = 0x60
INST_MICRO_OP_ADD_B = [SIG_ALU_OUT | SIG_REG_B_IN]
## this instrcutions substracts the content of REG_A and REG_B and saves the
## result in REG_A
INST_SUB_A = 0x70
INST_MICRO_OP_SUB_A = [SIG_ALU_SUB | SIG_ALU_OUT | SIG_REG_A_IN]
## this instrcutions substracts the content of REG_A and REG_B and saves the
## result in REG_A
INST_SUB_B = 0x80
INST_MICRO_OP_SUB_B = [SIG_ALU_SUB | SIG_ALU_OUT | SIG_REG_B_IN]
## this loads a new PC value
## the last for bits of this instruction are loaded into the REG PC
INST_PC_LOAD = 0x90
INST_MICRO_OP_PC_LOAD = [SIG_INST_OUT | SIG_PC_LOAD]
## halt instruction
## no new fetch cycle of the next instruction halts the PC
INST_HLT = 0xe0
INST_MICRO_OP_HLT = [0x0000]
INST_RESET = []
## fetch the instrcution itself from memory, and increment PC
INST_MICRO_OP_FETCH_INSTRUCTION = [MICRO_INST_PC_TO_REG_MEM_ADDRESS,
MICRO_INST_MEM_TO_INST | SIG_PC_TICK]
## list of all implemented instructions
## Mapping between instruction and control signals
INST = [[INST_LDA, INST_MICRO_OP_LDA],
[INST_LDB, INST_MICRO_OP_LDB],
[INST_REG_A_OUT, INST_MICRO_OP_REG_A_OUT],
[INST_REG_B_OUT, INST_MICRO_OP_REG_B_OUT],
[INST_ADD_A, INST_MICRO_OP_ADD_A],
[INST_ADD_B, INST_MICRO_OP_ADD_B],
[INST_SUB_A, INST_MICRO_OP_SUB_A],
[INST_SUB_B, INST_MICRO_OP_SUB_B],
[INST_PC_LOAD, INST_MICRO_OP_PC_LOAD]
]
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