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E. Technical data

For curious people, who want to know everything.

In Exec-Library are patched AllocMem (AllocVec, AllocPooled, CreatePool), Allocate (AllocEntry), AvailMem, AllocAbs and in the Device BeginIO.
Memory for the tracks is reserved decreasing (reverse).
The program was written in Oberon-2 and Assembler.
One track requires 16 Byte in the cache-structure.
Using Verify, memory of the size of one track is required per device.
The TrackDisk64 and SCSI-direct commands support "only" 40-Bit
```
2^40 =        1,0995 TeraByte   1125,9                GigaByte
2^64 = 18446744,074  TeraByte      1,8889465931776e10 GigaByte
```
The calculation is carried out with a "fast" 32-Bit division.
1226 GByte Festplatten will not be available until the 3rd millenium (by todays standards).
Only an offset which is divisible by 512 can be used. It would be possible to implement something else, but SCSI-drives don't support it anyway and there is no known program that doesn't read/write whole blocks (512 Bytes), so we can save a few bus-cycles here.
These device commands are understood:
- `include:exec/io.h'
  read, write, update,
- `include:devices/trackdisk.h'
  format, extFormat, extRead, extWrite, rawWrite, extRawWrite, extUpdate, motor, extMotor, protStatus, getGeometry, getDriveType, getNumTracks, eject
- trackdisk64
  read64, write64, format64
- NewStyleDevice (NSD)
  read64, write64, format64 Is used by FastFileSystem V43.x. => No problems with harddisks bigger than 4 GigaBytes anymore. See section 11.1 How to use harddisks bigger than 4 GigaBytes.. Informations about these commands can be found here:
  NSDDocs
  NSDPatch
- `include:devices/scsidisk.h'
  scsiCmd SmartFileSystem_SCSIdirect, FastFileSystem V44.5 und ProfiFileSystem-2_SCSIdirect use this command instead of the old trackdisk read/write commands.
  => No problems with harddisks bigger than 4 GigaBytes anymore. See section 11.1 How to use harddisks bigger than 4 GigaBytes.. Not all scsiCMD are used, because I don' have a documentation.
```
( SCSIProgrammer )
( (include:scsi/commands.h SCSI-2 include files) )

( Direct Access devices        =da )
( Write Once devices           =wo )
( CD-ROM devices               =cd )
( Scanner devices              =sc )
( Optical memory devices       =om )
( Sequential access devices    =sa )
( Printer devices              =prt)
( Processor devices            =cpu)
scsiREAD6         =$08 ( da wo cd    om )(not tested)
scsiREAD10        =$28 ( da wo cd sc om )
scsiREAD12        =$A8 (    wo cd    om )(not tested)

scsiWRITE6        =$0A (    wo       om )(not tested)
scsiWRITE10       =$2A (    wo       om )
scsiWRITE12       =$AA (    wo       om )(not tested)
```
  Has anyone a documentation for these commands?:
```
scsiREAD_BUFFER   =$3C ( da wo cd sc om sa prt cpu )
scsiWRITE_BUFFER  =$3B (    wo cd sc om sa prt cpu )
scsiUPDATE_BLOCK  =$3D (             om            )
```

E.1 What programmers should observe...

Data, which shall be written using the DOS functions Read/Write, should be LongWordAlligned (adr MOD 4=0), because the processor can access them faster then. This also applies to data which is sent directly to a device. AllocMem, Allocate... automatically return an address that is LongWordAlligned. So you only have to pay attention if you divide a memory block manually.
Remember: If you use SendIO instead of DoIO, the command is executed Async. Not only reading and writing, but also changeState, motor, protStatus, remove, changeNum ... commands.

E.2 Which values are the defaults?

At the first start and after choosing Edit/reset to Defaults from the menu, these values will be used:

Create Icons                                   = FALSE (OFF)

Not used FastMemory                            = 60 KB
Not used ChipMemory                            = 50 KB
FastMemFirst                                   = TRUE  (ON)
View color flash if track moved or deleted     = FALSE (OFF)
Protect tracks in memory with checksummes      = FALSE (OFF)

HD             Async delay                     = 4 seconds
Disk           Async delay                     = 7 seconds

Device| Pri | Settings
---------------------------------------------------------------------
DF0   | 100 | Removeable Disk, Write Async, Verify write
DF1   | 100 | Removeable Disk, Write Async, Verify write
DF2   | 100 | Removeable Disk, Write Async, Verify write
DF3   | 100 | Removeable Disk, Write Async, Verify write
DS0   |  80 | Removeable Disk, Write Async, Verify write
DS1   |  80 | Removeable Disk, Write Async, Verify write
DS2   |  80 | Removeable Disk, Write Async, Verify write
DS3   |  80 | Removeable Disk, Write Async, Verify write
PC0   |  60 | Removeable Disk, Write Async, Verify write
PC1   |  60 | Removeable Disk, Write Async, Verify write
PC2   |  60 | Removeable Disk, Write Async, Verify write
PC3   |  60 | Removeable Disk, Write Async, Verify write
PS0   |  40 | Removeable Disk, Write Async, Verify write
PS1   |  40 | Removeable Disk, Write Async, Verify write
PS2   |  40 | Removeable Disk, Write Async, Verify write
PS3   |  40 | Removeable Disk, Write Async, Verify write
CD0   |  20 | Removeable Disk, WriteRetention
HD0   |   0 | Write Async
HD1   |   0 | Write Async
HD2   |   0 | Write Async
HD3   |   0 | Write Async
DH0   |   0 | Write Async
DH1   |   0 | Write Async
DH2   |   0 | Write Async
DH3   |   0 | Write Async

E.3 Return values

The return values can be used within a shell-script.

Sys:Prefs/FDAPref ENVARC:FDA-AfterBoot.prefs USE
IF WARN ;FDA is not running
        RUN Sys:System/FDA ENVARC:FDA-AfterBoot.prefs QUIET
ENDIF

Sys:System/FDAView >NIL: Kill-FDA
IF NOT WARN ;FDA is running before
        RUN Sys:System/FDA ENVARC:FDA-AfterBoot.prefs QUIET
ENDIF

RUN Sys:System/FDA ENVARC:FDA-AfterBoot.prefs QUIET
IF $RC GE 5 ;FDA is running before
        Sys:Prefs/FDAPref ENVARC:FDA-AfterBoot.prefs USE
ENDIF

AlreadyRunning          = warn          (5)
PreferenceCancel        = error         (10)
PreferenceFDAnotRunning = warn          (5)
NoDeviceCached          = fail+1        (20 +1)
CanNotCreatePort        = fail+2
ReadArgsError           = fail+3
CanNotReadPrefs         = fail+4
CanNotCreateTask        = fail+5
AllocSignalError        = fail+6
NoMem                   = fail+777-fail

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