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Ensoniq SQ-80 Disk Format
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The disk contains data on both sides with 80 tracks numbered 0 - 79 on
each side.  However, each track has five 1024 byte sectors numbered
consecutively from zero to four followed by one sector of 512 bytes
with a sector ID of five.  I will refer to the two sides of the disk by
referring to the disk drive head used to read each side.  The heads are
numbered 0 and 1.  Data is stored on both sides of each track before
moving to the next track.  However, when switching tracks, the system
remains on the same head as the previous track.  The following examples
should clarify this.

   TK HD SC
    0  0 0-5  data is first stored on Track 0, Head 0, Sectors 0-5
    0  1 0-5  data is next stored on Track 0, Head 1, Sectors 0-5
    1  1 0-5  data is then stored on Track 1, Head 1, Sectors 0-5
    1  0 0-5  data is then stored on Track 1, Head 0, Sectors 0-5
    2  0 0-5  data is then stored on Track 2, Head 0, Sectors 0-5
              this process continues until....
   79  0 0-5  the last track - Track 79, Head 0, Sectors 0-5 
              (Track 79, Head 1, Sectors 0-5 were written first)

                    SQ-80 Sector Information

     Finding your way around an SQ-80 diskette is not an easy 
task.  Some of the files (and the directory) are stored on the 
smaller sectors, while others are stored on both!  All files on 
the SQ-80 are stored in fixed locations eliminating the need for 
a file allocation table.  The format allows for ten (10) large 
data files (any combination of one-sequence, all-sequence, or 
system-exclusive files).  Each file occupies 64 contiguous large 
sectors (sectors 0-4) of the diskette.  In addition, each of the 
ten files occupies one small sector (sector 5) located on the 
same track and head as the last large sector.  (Simply set the 
sector number to five after reading the last large sector).  This 
small sector is only used to store header information for the 
all-sequence files.  It is not used for the other two types.
    The format also allows for 40 program bank files.  These 
files occupy four large sectors each starting at Track 64, using 
the remaining large sectors on the diskette.  The diskette direc-
tory occupies the first four small sectors of the diskette as 
shown below.  The remaining small sectors are used to store the 
128 individual programs (sounds) with each program occupying one 
sector.  However, the program files are not on alternating sides.  
The first 64 are stored on head 0, and the last 64 are stored on 
head 1.  The ten program locations which conflict with the small 
sectors occupied by the large data files are stored in the small 
sectors starting at Track 66, Head 0, Sector 5. (I'm not making 
this up - this is really the way it works!)






 TK  HD  SC
  0   0   5   Directory (First Sector)
  0   1   5   Directory (Second Sector)
  1   1   5   Directory (Third Sector)
  1   0   5   Directory (Last Sector)
  2   0   5   Program # 1 
  3   0   5   Program # 2
  4   0   5   Program # 3
  5   0   5   Program # 4
  7   0   5   Program # 6 (Program # 5 stored at 66,0,5) 
  8   0   5   Program # 7
              Continues until....
 65   0   5   Program # 64
  2   1   5   Program # 65
  3   1   5   Program # 66
              Continues until....
 65   1   5   Program # 128
  0   0   0   Large Data File # 1 (First Sector)
  6   0   3   Large Data File # 1 (Last  Sector)
  6   0   4   Large Data File # 2 (First Sector)
  6   0   5   Large Data File # 1 (Small Sector)
 12   1   2   Large Data File # 2 (Last  Sector)
 12   1   3   Large Data File # 3 (First Sector)
 12   1   5   Large Data File # 2 (Small Sector)
 19   1   1   Large Data File # 3 (Last  Sector)
 19   1   2   Large Data File # 4 (First Sector)
 19   1   5   Large Data File # 3 (Small Sector)
 25   0   0   Large Data File # 4 (Last  Sector)
 25   0   1   Large Data File # 5 (First Sector)
 25   0   5   Large Data File # 4 (Small Sector)
 31   0   4   Large Data File # 5 (Last  Sector)
 31   0   5   Large Data File # 5 (Small Sector)
 32   0   0   Large Data File # 6 (First Sector)
 38   0   3   Large Data File # 6 (Last  Sector)
 38   0   4   Large Data File # 7 (First Sector)
 38   0   5   Large Data File # 6 (Small Sector)
 44   1   2   Large Data File # 7 (Last  Sector)
 44   1   3   Large Data File # 8 (First Sector)
 44   1   5   Large Data File # 7 (Small Sector)
 51   1   1   Large Data File # 8 (Last  Sector)
 51   1   2   Large Data File # 9 (First Sector)
 51   1   5   Large Data File # 8 (Small Sector)
 57   0   0   Large Data File # 9 (Last  Sector)
 57   0   1   Large Data File #10 (First Sector)
 57   0   5   Large Data File # 9 (Small Sector)
 63   0   4   Large Data File #10 (Last  Sector)
 63   0   5   Large Data File #10 (Small Sector)
 64   0   0   Program Bank # 1 (Sector 1 of 4)
 64   1   0   Program Bank # 2 (Sector 1 of 4)
 65   1   0   Program Bank # 3 (Sector 1 of 4)
 65   0   0   Program Bank # 4 (Sector 1 of 4)
              Continues until ....
 79   0   0   Program Bank # 40 (Sector 1 of 4) 






                 Ensoniq SQ-80 Directory Sectors

     The SQ-80 does NOT use its directory for the 128 individual 
programs stored on the disk.  These files are stored in a fixed 
location on the disk and must be read directly to obtain the 
names of the sounds.  Banks of sounds and the ten 64K files are 
listed in the regular directory but the position of the directory 
entries is fixed.  This eliminates the need for a file allocation 
table since the files are in fixed locations.  The first 10 
entries are for the ten large data (64K) files for sequences, all 
sequences, and system exclusive files.  The next 40 entries in 
the directory are for the 40 bank files.

                 Ensoniq SQ-80 Directory Entries 

Each Entry contains 13 bytes of data.

Byte   Information

 01    File Type - see list of types
02-11  File Name (10 Bytes)
 12    Type-dependant Information
 13    Type-dependant Information

The SQ-80 File Names can contain some unusual characters since 
the keyboard used some non-ACSII characters.  See Joe Slater's 
article (Issue #70, page 13) to find out the meaning of these 
characters.  In fact, Joe's entire series of articles on the 
ESQ-1 are valid for the SQ-80 as well.

                    Ensoniq SQ-80 File Types

00 (00) = Unused (Blank)
01 (01) = Operating System
02 (02) = Program Bank File
03 (03) = All Sequence File
04 (04) = One Sequence File
05 (05) = System Exclusive File
06 (06) = Single Program File