Heading:

Mesa 6.0 System Update

Page Numbers: Yes X: 527 Y: 10.5"

Copyright c Xerox Corporation 1980

Inter-Office Memorandum

ToMesa UsersDateOctober 27, 1980

FromJohn WickLocationPalo Alto

SubjectMesa 6.0 System UpdateOrganizationSDD/SS/Mesa

XEROX

Filed on: [Iris]<Mesa>Doc>System60.bravo (and .press)

This memo outlines changes made in the Mesa system interfaces since the last release (Mesa 5.0, April 9, 1979). A number of internal changes made in the system and the microcode are also discussed.

This memo is intended as a quick guide to conversion, not a detailed specification of the changes. Names in square brackets refer to sections of the Mesa System Documentation or to other publicly available reference documents (e.g., the Alto Operating System Reference Manual).

External Interfaces

Major changes include integrated support for Alto extended memory and elimination of BasicMesa. The System also now exports versions of the following Development Software interfaces: Ascii, Format, Inline, Process, Runtime, Storage, String, System, and Time. (Note that implementation of these interfaces may not be complete.) Other changes are relatively minor.

AllocDefs

Private types and operations have been removed. AllocInfo, MakeDataSegment, and MakeSwappedIn are now defined in SegmentDefs, and temporarily duplicated here for compatibility. [Segment Package]

AltoDefs

MaxVMPage has been increased to support up to a million words of memory; MaxMDSPage and PagesPerMDS have been added. [Segment Package]

AltoDisplay

MaxBitsPerLine has been changed to 608 (it was 606). Cursor, CursorBits, and CursorHandle define the location and format of the cursor. Coordinate, CursorXY, and MouseXY define the location and format of the cursor and mouse coordinates. [Display Package]

AltoFileDefs

Support for the DiskShape and PartitionName properties of the directory’s leader page has been added. The definition of a file serial number (SN) has been changed to isolate the flag bits (directory, random, and nolog) into a separate structure (SNBits). [Alto Operating System Reference Manual]

AltoHardware

This new interface defines most structures of the Alto hardware, including the processor, display, keyboard, mouse, keyset, printer interface, disk, and Ethernet. [Alto Hardware Manual]

Ascii

This new interface defines the ASCII control character codes; for compatibility, these continue to be defined in IODefs. [StreamIO Package]

BasicMesa

The facilities of BasicMesa have been replaced by procedures in the standard system and a command line switch (/b) which can be used to destroy the display and keyboard packages (see DisplayDefs and StreamDefs). MakeImage is no longer a standard part of Mesa.image, and must be loaded separately. [Section 3]

BitBltDefs

The extended memory option now supports use of the normal and alternate bank registers, whose values are supplied in the unused word of the BBTable (this option is not supported under XMesa 5.0 microcode (version 39)). AlignedBBTable (and BBTableSpace) can be used to properly align BITBLT argument records. [Alto Hardware Manual]

CharIO

This new interface provides many of the functions of IODefs, but each operation takes a StreamDefs.StreamHandle as its first parameter, allowing formatted input and output to any standard stream. [StreamIO Package]

DirectoryDefs

This interface has been changed slightly to speed up directory searches (by about a factor of 3). In addition, support for subdirectories was added (see Alto Operating System Reference Manual). The following items have changed (note that a NIL DiskHandle does not imply the system directory):

EnumerateEntries: PROCEDURE [
dir: DiskHandle,
proc: PROCEDURE [CARDINAL, StreamScan.Handle, DEptr] RETURNS [BOOLEAN],
inspectFree: POINTER TO READONLY BOOLEAN,
lengthFilter: CARDINAL ← 0] RETURNS [index: CARDINAL];

The procedure proc is called for each directory entry; free entries are passed only if inspectFree↑ is TRUE. If the lengthFilter is non-zero, only entries with a filename length equal to lengthFilter characters will be passed to proc.

The following procedure inserts an entry into the directory; unlike Lookup, it does not create a file. If the file already exists, TRUE is returned (and fp↑ is undisturbed).

Insert: PROCEDURE [
dir: DiskHandle, fp: POINTER TO AltoFileDefs.FP, name: STRING]
RETURNS [old: BOOLEAN];

ParseFileName replaces ExpandFileName; it strips the leading directory information from name, puts the result in filename (appending a period if necessary), and returns a stream (with access dirAccess) open on the directory in which the file should be looked up.

ParseFileName: PROCEDURE [
name, filename: STRING, dirAccess: SegmentDefs.AccessOptions]
RETURNS [StreamDefs.DiskHandle];

The following procedures set and return the directory used for looking up files which do not specify a directory name (initially set to "<SysDir.").

SetWorkingDir: PROCEDURE [dir: SegmentDefs.FileHandle];

GetWorkingDir: PROCEDURE RETURNS [dir: SegmentDefs.FileHandle];

Finally, the signal BadDirectory no longer takes a string parameter. [Directory Package, Alto Operating System Reference Manual]

DisplayDefs

DestroyDisplay can be used to delete the display package; it turns off the display, deallocates the bitmap, destroys the font, and UNNEWs all the display modules. [Display Package]

DoubleDefs

This interface is no longer implemented or supported, since LONG data types are now a standard part of the language and runtime support.

FrameDefs

Validate(Global)Frame and Invalid(Global)Frame now take (return) UNSPECIFIED. The procedure

LoadConfig: PROCEDURE [name: STRING] RETURNS [PROGRAM];

loads a configuration without starting it and returns its control module or control module list (or NIL if there is no control module). Note that this will not handle configurations whose control modules take parameters. [Modules]

FSPDefs

The error ZoneTooLarge is now raised by Make(New)Zone and AddTo(New)Zone when an attempt is made to make a zone of more than 32K words. [Storage Management]

ImageDefs

MakeImage takes an optional second parameter (merge: BOOLEAN ← TRUE); MakeUnMergedImage has been temporarily retained for compatibility. The ImageMaker package is no longer a part of the standard system; it must be loaded or bound with the client configuration. [Image Files]

InlineDefs

The LongCOPY operation for use with long pointers is now implemented by the extended memory microcode. The types BytePair and BcplLongNumber have been added; the procedures MesaToBcplLongNumber and BcplToMesaLongNumber implement conversion between Mesa and BCPL long numbers. [Miscellaneous]

IODefs

The procedure WriteSubString has been added. [StreamIO Package]

MiscDefs

The ByteBlt procedure has been added. [Miscellaneous]

MiscOps

ReleaseDebuggerBitmap can be used to free the storage normally allocated (on extended memory machines) for the Debugger’s bitmap. [Section 3]

OsStaticDefs

The type of ClockSecond has been changed to use InlineDefs.BcplLongNumber. [Alto Operating System Reference Manual]

ProcessDefs

Aborted has been redefined to be equal to the predeclared error ABORTED. A Pause procedure has been added which delays execution of its caller by the specified number of ticks. Detach and GetCurrent now take (return) a PROCESS instead of an UNSPECIFIED. [Processes and Monitors]

SegmentDefs

The majority of changes in SegmentDefs are due to the incorporation of XMesa and extended memory support into the standard system. Clients of XMesa should see the XMesa update document.

The definition of SegmentObjects has changed to allow for a twelve bit page number. The read bit in FileSegmentObjects has been deleted (read access is always assumed) and MaxSegLocks has been reduced to fifteen (MaxSegLocks and MaxFileLocks replace MaxLocks).

A type field has been added to DataSegmentObjects with predefined values UnknownDS, FrameDS, TableDS, HeapDS, SystemDS, BitmapDS, StreamBufferDS, and PupBufferDS. These types are interpreted by the Debugger’s Coremap command.

For clients of low level memory allocation, the definition of AllocInfo has changed and the constants HardUp, HardDown, EasyUp, and EasyDown have been defined. The procedures MakeDataSegment and MakeSwappedIn have been moved here from AllocDefs.

The access options ReadWrite, WriteAppend and ReadWriteAppend have been added. NewFile and InsertFile now default the access and version parameters.

The following two procedures have been added to provide access to file times:

GetFileTimes: PROCEDURE [file: FileHandle]
RETURNS [read, write, create: TimeDefs.PackedTime];

SetFileTimes: PROCEDURE [
file: FileHandle,
read, write, create: TimeDefs.PackedTime ← TimeDefs.DefaultTime];

GetFileTimes does not modify any of the file’s times. In SetFileTimes, if any of the times are defaulted, the current time is used. [Segment Package]

StreamDefs

DestroyKeyHandler can be used to delete the standard keyboard handler; it destroys the keyboard process and UNNEWs all the keyboard modules. [Keyboard]

The type StreamPosition, defined as a LONG CARDINAL, can be used in place of a StreamIndex. The operations GetPosition, SetPosition, and ModifyPosition are similar to the corresponding index operations; IndexToPosition and PositionToIndex perform conversions between positions and indicies. The access options ReadWrite, WriteAppend, and ReadWriteAppend have been added, as has the signal FileNameError. [Disk Streams]

StreamScan

This new interface allows overlapped disk input when reading from a stream. It is a transliteration of the same code from the Alto Operating System (version 17). The following are defined in StreamScan.mesa:

Descriptor: TYPE = RECORD [
da: AltoFileDefs.vDA,
pageNumber: CARDINAL,
numChars: CARDINAL,
-- private fields];

Handle: TYPE = POINTER TO READONLY Descriptor;

Init: PROCEDURE [
stream: StreamDefs.StreamHandle, bufTable: POINTER, nBufs: CARDINAL]
RETURNS [Handle];

GetBuffer: PUBLIC PROCEDURE [ssd: Handle] RETURNS [POINTER];

Finish: PROCEDURE [ssd: Handle];

Init sets up a scan stream from a disk stream. In addition to the stream, the client supplies a vector of pointers to 256 word areas useable as disk buffers (bufTable). The number of buffers supplied is nBufs. At least one buffer must be supplied (the normal stream buffer is also used). Each call to GetBuffer will return a pointer to the next sequential page of the file and returns the previous buffer page to the buffer pool (first call returns data page 0; file page 1). The public fields of the Handle are correct for the page returned by the most recent call to GetBuffer. GetBuffer returns NIL when there are no more pages to be read. A call to Finish terminates the scan. No other stream operations should be performed between Init and Finish. [Disk Streams Package]

StringDefs

CompareStrings lexically compares two strings and returns -1, 0, or 1 if the first is less than, equal to, or greater than the second; an optional parameter may be supplied to ignore case differences. All procedures in this interface now handle NIL string parameters. [String Package]

SystemDefs

CopyString allocates storage from the system heap and copies its argument into it, optionally making the new string longer. ExpandString performes a similar function, allocating a new string (and freeing the old one) if necessary. Even and Quad can be used to align pointers on double and quad word boundaries. [Storage Management]

TimeDefs

The type HardwareTime has been replaced by InlineDefs.BcplLongNumber. Default values have been added to UnpackDT, PackDT, and AppendDayTime. ReadClock returns the current value of the Alto’s realtime clock (part of which can be found at location RealTimeClock). [Time Package]

TrapDefs

StackError no longer takes a parameter; UnboundProcedure now takes an UNSPECIFIED. The following signals have been added (not all of which can be generated by Alto/Mesa): ZeroDivisor, DivideCheck, UnimplementedInst, WakeupError, PageFault, Write-ProtectFault, and HardwareError. [Traps]

XMesa Extended Memory Support

Functions formerly provided by XMesa are now integrated with the standard system. A 3K RAM or Mesa microcode in ROM1 is required to support the extended memory option. [Segment Package]

Internal Interfaces

The following changes are internal to the implementation and do not affect public interfaces; they may affect performance and/or space requirements, however. Note that Mesa 6.0 continues to support version 39 of the XMesa microcode available with Mesa 5.0; obviously, certain new features listed below are not available if your ROM contains the old microcode (e.g., Long BitBlt).

3K RAM Support

Mesa now supports the Alto 3K RAM option (available only on extended memory machines).

Debugger Bitmap

If the extended memory option is present, the system allocates part of the client’s memory for use by the debugger for its display bitmap; this improves the debugger’s response times considerably. The debugger bitmap may be deallocated by the procedure MiscOps.ReleaseDebuggerBitmap or the command line switch /k (in the former case, the call must be made before the debugger is first entered).

Long Copy, Long BitBlt

These opcodes now include support for extended memory.

Misc Opcodes

Misc opcodes (except for RCLK) now provide a general escape to user microcode in the RAM if Mesa is running on a 2K ROM or 3K RAM machine; they produce undefined results otherwise. Alpha bytes for the currently implemented MISC functions are defined in MiscAlpha.

Overflow Microcode

RunMesa has been upgraded to include microcode support for Pup checksums, IEEE floating point, and HBlt (used by Griffin). This microcode is loaded with the XMesa overflow microcode on Altos with the 2K ROM (with version 41 microcode) or 3K RAM option. Users who have been loading microcode for these functions need no longer do so. This change affects Alto IIs only.

Range Checking

The bounds check instruction (BNDCK) is now implemented correctly.

Distribution:
Mesa Users
Mesa Group
SDSupport