Hardware manual

Operating System Software Packages
Several of the modules of the operating system are also available as software packages in case the
programmer wishes to include them in overlays, or modify them, etc. The sources are in
<AltoSource>OSSources.dm, and the binaries are in <Alto>OSBrs.dm. You are urged to get listings and
ponder them since proper use of these procedures in a foreign context may require some modifications,
and will certainly require some understanding. The BootBase package, in the BuildBoot documentation in
the Subsystems manual, offers configurations of these packages that permit making most any subsystem
into a boot file without souce level changes.
Utilities. The file OsUtils.Bcpl contains several of the utility procedures located in levMain: Wss, Ws, Wl,
Wns, Wos, Wo, GetFixed, FreeFixed, FixedLeft, SetEndCode. The procedure GetFixedInit must be
called to initialize the GetFixed/FreeFixed procedures.
Password. The file Password.Bcpl contains the Alto password routines, and can be used to do password
checking in subsystems.
Keyboard. The keyboard handler is available in KeyStreamsB.Bcpl, KeyStreamsA.Asm and
LevBuffer.asm. The procedure CreateKeyboardStream initializes the package, and returns a value (keys)
that can be used as a keyboard stream.
Display. The display handler is available in the file DspStreamsB.Bcpl and DspStreamsA.Asm.
Documentation is found later in this manual.
Directory. The file Dirs.Bcpl contains the directory manipulations described in section 3.5.
Fast Streams. The files FastStreamsB.bcpl and FastStreamsA.asm implement fast streams to memory.
Documentation is part of DiskStreams.
Disk Streams. The files DiskStreams.bcpl, DiskStreamsMain.bcpl, and DiskStreamsAux.bcpl contain
procedures for implementing disk streams. The fast file scanning facilities require the additional file
DiskStreamsScan.bcpl. Documentation is found later in this manual.
Alloc. The file Alloc.Bcpl implements the allocator. See documentation later in this manual.
Basic File System. The files BfsInit.bcpl, BfsBase.Bcpl, BfsWrite.Bcpl, BfsCreate, BfsClose.bcpl,
BfsDDMgr.bcpl, BfsNewDisk.bcpl and BfsFindHole.bcpl implement the basic file system (documentation
appears later in this manual). They are maintained separately from the OS (sources:
<AltoSource>BFSSources.dm; BRs: <Alto>BFSBRs.dm). They require Calendar.Asm, Dvec.Bcpl,
Calls.Asm, BcplTricks.asm and SysErr.bcpl in order to operate.
Alto Operating System May 5, 1980 38
For Xerox Internal Use Only -- December 15, 1980