This code is to calculate e from the infinite series for e^x:
e=1++1+1/2!+1/3!+1/4!+...

format: (4 enable bits)(hex:r on A bus)(hex:r on B bus)(hex: updated r on D bus) opcode
         ^^^^=(2x PC update, A bus valid, B bus valid, D bus valid)

mov r0 rB	1011x0B mov opcode #rB to hold small
small float
mov r0 rC	1011x0C mov opcode #rC to hold 1.0 to increment k
1.0
mov rC rA	0011xCA mov opcode #rA to hold sum
fadd rC rA rA	0111CAA fadd opcode # starts 1+1
mov rC rD	0011xCD mov opcode #rD to hold k!
mov rC r9	0011xC9 mov opcode #r9 to hold k
mov r0 r8	1011x08 mov opcode
2
mov rF rE	0011xFE mov opcode
add r8 rE rE	01118EE add opcode  #note (rE) is address of following instruction
fadd rC r9 r9	0111C99 fadd opcode # k<-k+1.0
fmul r9 rD rD	01119DD fmul opcode # k+1!<-(k+1)*k!
finv rD r2	0011xC2 finv opcode #r2 will be 1/2!, 1/3!, 1/4!
fadd r2 rA rA	0111CDC fadd opcode #current total sum
fcmp r2 rB	01102Bx fcmp opcode = fsub opcode wiht no D
bpl rE		0011xEF plus condition mov rE rF opcode
mov r0 rE	1011x0E mov opcode
address to output e
store rA rE	0110AEx store opcode
halt

   sum             added term
   2.50000000      0.500000000    
   2.66666675      0.166666672    
   2.70833325       4.16666679E-02
   2.71666670       8.33333377E-03
   2.71805549       1.38888892E-03
   2.71825385       1.98412701E-04
   2.71827888       2.48015876E-05
   2.71828151       2.75573188E-06
   2.71828175       2.75573200E-07
   2.71828175       2.50521079E-08
   2.71828175       2.08767559E-09
   2.71828175       1.60590444E-10
   2.71828175       1.14707454E-11
   2.71828175       7.64716361E-13
   2.71828175       4.77947726E-14
   2.71828175       2.81145736E-15
   2.71828175       1.56192068E-16
   2.71828175       8.22063508E-18
   2.71828175       4.11031759E-19
   
   sum                       deviation: exact-sum
   2.7182818284590455       -4.4408920985006262E-016