The Mirage has a format similar to the SQ-80 keyboard. However, the
disk only contains data on one side of the disk with 80 tracks numbered
0 - 79. Like the SQ-80, 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. The following examples should clarify this.
TK SC SIZE
0 0-4 1024 data is first stored on Track 0, Sectors 0-4
0 5 512 data is next stored on Track 0, Sector 5
1 0-4 1024 data is next stored on Track 1, Sectors 0-4
1 5 512 data is next stored on Track 1, Sector 5
this process continues until...
79 5 512 the last track - Track 79, Sector 5
The diskette may contain the Operating System, six sounds config- ured
as 3 lower-half keyboard sounds and 3 upper-half keyboard sounds and
either eight short sequences or three long sequences. The first 11K of
the Operating System is stored on both small and large sectors from
Track 0, Sector 0, to Track 1, Sector 5. The remaining 5k of the
Operating System is stored only on small sectors (Sector 5) from Track
2 to Track 10. The configuration parameters are stored on Track 11,
Sector 5. The directory and the sequences are only stored on the small
sectors (Sector 5) and the sound files are only stored on the large
sectors (Sectors 0-4).
TK SC
2 0 Sound # 1, Lower Half, Parameters ( 1 Sector )
2 1 Sound # 1, Lower Half, Data (64 Sectors)
15 0 Sound # 1, Upper Half, Parameters ( 1 Sector )
15 1 Sound # 1, Upper Half, Data (64 Sectors)
28 0 Sound # 2, Lower Half, Parameters ( 1 Sector )
28 1 Sound # 2, Lower Half, Data (64 Sectors)
41 0 Sound # 2, Upper Half, Parameters ( 1 Sector )
41 1 Sound # 2, Upper Half, Data (64 Sectors)
54 0 Sound # 3, Lower Half, Parameters ( 1 Sector )
54 1 Sound # 3, Lower Half, Data (64 Sectors)
67 0 Sound # 3, Upper Half, Parameters ( 1 Sector )
67 1 Sound # 3, Upper Half, Data (64 Sectors)
20 5 Short Sequence # 1 (4 Sectors)
35 5 Short Sequence # 2 (4 Sectors)
55 5 Short Sequence # 3 (4 Sectors)
24 5 Short Sequence # 4 (4 Sectors)
28 5 Short Sequence # 5 (4 Sectors)
39 5 Short Sequence # 6 (4 Sectors)
43 5 Short Sequence # 7 (4 Sectors)
59 5 Short Sequence # 8 (4 Sectors)
12 5 Long Sequence # 1 (16 Sectors)
35 5 Long Sequence # 2 (16 Sectors)
55 5 Long Sequence # 3 (16 Sectors)
Mirage Directory Sectors
The directory information for the Mirage is contained in three
bytes which are stored in three sectors of the diskette. Each
sector contains 512 copies of the directory byte for that sector.
This was done because there wasn't any buffer space to read a
whole directory sector. Therefore, the Mirage would read (or
write) the sector and would use the last byte of the sector as
the valid value for the directory byte. Track 32, Sector 5
contains the Sound Directory Byte. Track 33, Sector 5 contains
the Short Sequence Directory Byte and Track 34, Sector 5 contains
the Long Sequence Directory Byte. The directory bytes are de-
fined as follows:
SOUND DIRECTORY BYTE SHORT SEQUENCE LONG SEQUENCE
DIRECTORY BYTE DIRECTORY BYTE
Bit 0 Not Used Bit 0 Seq. 1 Bit 0 Seq. 1
Bit 1 Sound 1 Lower Bit 1 Seq. 2 Bit 1 Seq. 2
Bit 2 Sound 1 Upper Bit 2 Seq. 3 Bit 2 Seq. 3
Bit 3 Sound 2 Lower Bit 3 Seq. 4 Bit 3 Not Used
Bit 4 Sound 2 Upper Bit 4 Seq. 5 Bit 4 Not Used
Bit 5 Sound 3 Lower Bit 5 Seq. 6 Bit 5 Not Used
Bit 6 Sound 3 Upper Bit 6 Seq. 7 Bit 6 Not Used
Bit 7 Not Used Bit 7 Seq. 8 Bit 7 Not Used
If the Sound or Sequence exists, the appropriate bit is set to
one (1). If not, the bit is cleared (0).
As the various formats suggest, Ensoniq has come a long way
since the Mirage single-sided drives. I would like to suggest
that they consider the possibility of using the higher density
1.44 megabyte diskette drives in the future. The drives (and
diskettes) are not that much more expensive, but they would make
a big difference especially with the EPS-16. The lower density
diskettes could still be used with the higher density drives
giving us the option of which diskettes we want to buy. If new
formats are introduced, I will try to include their formats in
future issues of the Hacker. If you have questions concerning
the formats, please feel free to contact me. I have used the
information in this article to restore files on diskettes which
had been 'trashed' by some glitch in the keyboards. If you have
a disk you thought was forever lost, you may be able to recover
the files using this information. In my next article, I will
cover the format used for the VFX-SD Sequencer.
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