Description

This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.

09.017 How does one distinguish between a 13 and 16-sector Disk ][ controller card?

         For a while at least, new 16-sector Disk II cards shipped with a little
white circular sticker depicting a red Apple with the number "16" in the
middle.

     But the sticker is hardly a reliable test.  A better test is to look look
at the part numbers of the P5 PROM (the lower left chip on the card) and the P6
PROM (left column, second from the top).

          13-sector    16-sector
          ---------    ---------
     P5   341-0009-xx  341-0027-xx
     P6   341-0010-xx  341-0028-xx

The 16-sector PROMs may also be labelled "P5A" and "P6A".

A program can test the card type by looking at its slot ROM space.  The
signature bytes are as follows:

     $Cn01: 20
     $Cn03: 00
     $Cn05: 03
     $Cn07: 3C
     $CnFF: FF if 13-sector; 00 if 16-sector

For example,

     1  REM Scan the slots for Disk II interfaces
     2  REM By Neil Parker
     10  FOR S = 1 TO 7
     20 A = 49152 + 256 * S
     30  IF  PEEK (A + 1) <  > 32 OR  PEEK (A + 3) <  > 0 OR
        PEEK (A + 5) <  > 3 OR  PEEK (A + 7) <  > 60 THEN 100
     40  PRINT "Disk II (";
     50 T =  PEEK (A + 255)
     60  IF T = 0 THEN  PRINT "16-sector";: GOTO 90
     70  IF T = 255 THEN  PRINT "13-sector";: GOTO 90
     80  PRINT "other";
     90  PRINT ") in slot "S
     100  NEXT

By:  Dan DeMaggio
    

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