So where does the PNP ID come from in the EDID?

Looking at the EDID, where is the manufacturer code and the monitor ID?

The wikipedia EDID article tells us that bytes 8-9 are the Manufacturer ID and bytes 10-11 are the product code.

8–9 Manufacturer ID.

These IDs are assigned by Microsoft, they are PNP IDs "00001=A”; “00010=B”; ... “11010=Z”. Bit 7 (at address 08h) is 0, the first character (letter) is located at bits 6 → 2 (at address 08h), the second character (letter) is located at bits 1 & 0 (at address 08h) and bits 7 → 5 (at address 09h), and the third character (letter) is located at bits 4 → 0 (at address 09h).
Bit 15 (Reserved, always 0)
Bits 14–10 First letter of manufacturer ID (byte 8, bits 6–2)
Bits 9–5 Second letter of manufacturer ID (byte 8, bit 1 through byte 9 bit 5)
Bits 4–0 Third letter of manufacturer ID (byte 9 bits 4–0)

10–11 Manufacturer product code. 16-bit number, little-endian.


So let's make a little LibreCalc spreadsheet and a function to get the bits:

function bits(value, lowbit, highbit as double)as double
  retval = 0
  for i = lowbit to highbit
    retval = retval + (value and (2^i))
  next i
  retval = retval / (2^lowbit)
  bits = retval  
end function

then a table from a1:31 with the numbers 1 to 31
a table from b1:31 with the formula =CHAR(A1+UNICODE("A")-1) in b1 and fill copy it to b31. I'm so used to using the ASC function but now I guess it has to be UNICODE.

and to see the bit patterns, why not fill c1:c31 with =DEC2BIN(A1,5) to pad it to 5 binary digits.

then to translate a 5 bit letter code to a letter, we go:

=LOOKUP(lettercodenumber,A1:A31,B1:B31)

and to get the bits for a specific range let's use the bits routine:

=bits(number,14,10) for bits 10 to 14



Let's use cell f4 for our : 10ac

put a =HEX2DEC(f4) into g4

and the following into cell h4

=LOOKUP(BITS(G4,10,14),$A$1:$A$31,$B$1:$B$31)&
LOOKUP(BITS(G4,5,9),$A$1:$A$31,$B$1:$B$31)&
LOOKUP(BITS(G4,0,4),$A$1:$A$31,$B$1:$B$31)

And now you can convert that hex code to a manufacturer ID.

The product code is easy, just reverse the little endian:

So if your hexdump looks like this:

00000000 00 ff ff ff ff ff ff 00 10 ac 15 a0 35 34 38 36 |................|

10ac = DEL
15a0 = A015

for the PNP code of DELA015


And if you want to get rid of the lookup table, you can just compute it with another function:

function pnpletter(code) as string  
  pnpletter=chr$(code+ASC("A")-1)
end function

which makes our cell h4 formula

=PNPLETTER(BITS(G4,10,14))&PNPLETTER(BITS(G4,5,9))&PNPLETTER(BITS(G4,0,4))



It would have been neat to have it "human readable" without bit fiddling but I guess they wanted to save a byte here and there.