Fairchild 9401 ttl ic pinout wanted.

Tony Duell ard at p850ug1.demon.co.uk
Fri Nov 9 19:39:59 CST 2007


> 
> 
> Anyone has the above ?
> 
> It is a 14 pin TTL IC, according to google some sort of CRC generator.
> It is part of the mididisk controller of the ETH Lilith, which I am 
> reverse engineering.

Philips/Signetics second-sourced it, and I have the datasheet in front of 
me. There's also the Signetics 8X01A, which is similar, but with the 
extra feautre of beign able to do the SDLC-specificed patern match. It's 
a fairly common device in old discrete-ish logic disk controllers

Anyway, here's a pinout and some notes
1 : CP/
2 : P
3 : S0
4 : MR
5 : S1
6 : N/C (Pattern Match Enable on 8X01A)
7 : Ground
8 : S2
9 : N/C
10 : CWE
11 : D
12 : Q 
13 : ER
14 : Vcc

Where : 

CP/ = Clock Pulse Input (falling edge triggered)
D = Data input
Q = Data Output
CWE = Check Word Enable. basiucally. this is held high while data bits 
are applied to the D input, the polynomial value is calculated in an 
inteernal shift register. Then CWE is taken low and the contents of this 
regiser shifted out on the Q output.
MR = Mater Reset
P = Presett (polynomal register to apporpriate value)
ER = Error flag output
S2...S0 = Polynomial select inputs. Reading these as an octal digit (S2 
is the MSB), the polynomailas are : 
0 : X^16 + X^15 + X^2 +1 (CRC-16)
1 : X^16 + X^14 + X + 1 (CRC-16 Reverse)
2 : X^16 + X^15 + X^13 + X^7 + X^4 + X^2 + X  + 1
3 : X^12 + X^11 + X^3 + X^2 + X + 1 (CRC-12)
4 : X^8 + X^7 + X^5 + X^4 + X + 1
5 : X^8 + 1 (LRC-8)
6 : X^16 + X^12 + X^5 + 1 (CRC-CCITT)
7 : X^16 + X^11 +X^4 +1 (CRC-CCITT Reverse)

Hope that helps. There's not much more in the data sheet other than 
tables of timeing and electical characteristics, which you probably don't 
need.

-tony




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