4bit CPU DL167 is an address extension of DL166.
#Registers 0:0000 ACC 1:0001 GR1 2:0010 GR2 3:0011 GR3 4:0100 GR4 5:0101 INPUT PORT(read only) 6:0110 OUTPUT PORT(write only) 7:0111 Program Counter(PC low nibble) 8:1000 Program Counter(PC hi nibble) #Instruction Set 01-000-sss ADD (sss) acc=acc+(sss) 01-001-sss OR (sss) acc=acc | (sss) 01-010-sss AND (sss) acc = acc & (sss) 01-011-sss XOR (sss) acc = acc ^ (sss)
01-100-sss INC (sss) (sss)=(sss)+1 01-101-sss NOT (sss) (sss)=!(sss) 01-110-sss RSHIFT (sss)(sss)=(sss)>>1 01-111-sss LSHIFT (sss)(sss)=(sss)<<1
10-00-#### JNC #### if (C==0) PC=#### else PC=PC+1 10-01-#### JMP #### PC_LOW = ####,PC_HI = R4 10-10-#### SET #### acc=####
00-ddd-sss MOV (ddd),(sss)
#Files DL167.v CPU and Memory Verilog-HDL Source files
testbench3.v Test bench for DL167
asm.txt sample code to test DL167. // this program is counting up R0 register and show this on LEDs. 00: mov R0,f 01: mov R4,R0 02: jmp 0
f0:inc r0 f1:mov r6,r0 f2:jmp 0