Re: 13 sector or 16 sector Disk ][ card?

[nparker@cie-2.uoregon.edu (Neil Parker)]

In article <pdueck-1406970030180001@dial15.pli.mb.ca> pdueck@pli.mb.ca (Perry
Dueck) writes:
>Perhaps a bit of a stupid question, but here it goes anyways (for my
>benefit if nothing else):    :)
>
>How would one distinguish between a Disk ][ card which is capable of 13
>sectors (original...wayyyyy back in the early days of the Apple ][), and a
>16 sector Disk ][ interface card?  Are the ROM chips marked with a special
>number to distinguish between the two different kinds or something?

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: 00 if 16-sector, FF if 13-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


                   - Neil Parker
-- 
Neil Parker, nparker@{cie-2,cie}.uoregon.edu, http://cie-2.uoregon.edu/~nparker
     "I was going to be a neo-deconstructivist but Mom wouldn't let me."
                                     -- Calvin and Hobbes, 7/13/1995
Unsolicited commercial e-mail to my address will be discarded unread.