CP/M/CPM_CDROM.iso/enterprs/c128/util/xlink.sda/XLINK.DOC

Text File | 1992-09-30 | 11KB | 191 lines

╨ART ╔╔ - ┴ ╨RACTICAL ┼XAMPLE OF ─ATA ╨ORTABILITY

├╥╧╙╙ ╠╔╬╦ IS A SHORT ┬┴╙╔├ 7 PROGRAM FOR USE ON THE ├-128 WITH A SINGLE
1571 DRIVE.  ╔T ALLOWS YOU TO READ A FILE INTO A 45 K ╥┴═ BUFFER FROM ANY ONE
OF THE FOLLOWING SEVEN DISK FORMATS:

    ╙┼╤ - ┴╙├╔╔
    ╙┼╤ - WITH ╨┼╘╙├╔╔ <> ┴╙├╔╔ CONVERSION
    ╨╥╟ - ┴╙├╔╔
    ╨╥╟ - WITH SCREEN CODE <> ┴╙├╔╔ CONVERSION
    ├-128 ├╨/═ SINGLE SIDED
    ├-128 ├╨/═ DOUBLE SIDED
    ╔┬═ ╨├-─╧╙ DOUBLE SIDED, 9 SECTORS/TRACK

╘HE BUFFER CAN THEN BE WRITTEN TO ANOTHER DISK IN ANY OF THE SAME LIST OF
FORMATS OR TO A PRINTER.  (╔T SHOULD BE NOTED THAT THE ╔┬═ ╨├-─╧╙ DOUBLE
SIDED FORMAT IS ╬╧╘ THE SAME AS THE "╔┬═-─╙" WHICH IS SUPPORTED BY ├-128 ├╨/═
MODE.  ╘HE LATTER FORMAT IS USED BY ├╨/═-86 WHICH IS THE 16 BIT VERSION OF
├╨/═ DESIGNED TO RUN ON THE ╔┬═-╨├ INSTEAD OF ╨├-─╧╙.  ╨├-─╧╙ AND ├╨/═-86
ARE NOT COMPATIBLE.)  ├╥╧╙╙ ╠╔╬╦ IS SIMPLE TO USE, JUST FOLLOW THE PROMPTS ON
THE SCREEN.  ╧NE WORD OF CAUTION, HOWEVER.  ┬ECAUSE THE 1571 IS NOT A TRUE
╨├-─╧╙ DISK DRIVE, NEVER WRITE ╨├-─╧╙ FILES TO AN ORIGINAL, IRREPLACEABLE
DISK.  ╨LAY IT SAFE, ALWAYS USE SCRATCH DISKS FOR WRITING FILES.  (┴LTHOUGH
╔ HAVE HAD NO PROBLEMS WITH DISKS FROM THREE DIFFERENT ╔┬═-╨├S AND TWO ╨├
COMPATIBLES, THE POSSIBILITY DOES EXIST FOR MIS-MATCHED SECTOR TIMING, ETC.
╘HIS COULD HOPELESSLY CORRUPT THE DISK BEING WRITTEN TO.)

├╥╧╙╙ ╠╔╬╦ USES BURST MODE ON THE 1571 TO READ AND WRITE ╨├-─╧╙ AND ├╨/═
FILES, CONSEQUENTLY IT IS QUITE FAST.  (┴ DETAILED DESCRIPTION OF 1571
BURST MODE AND HOW TO USE IT IS PRESENTED IN A SERIES OF ARTICLES BY
THIS AUTHOR IN ╘╨╒╟ MAGAZINE, STARTING IN ═AY 1986.)  ┴ TYPICAL CONVERSION
OF A 16K (65 ╙┼╤ BLOCK) TEXT FILE FROM ╙┼╤ ╨┼╘╙├╔╔ TO ╨├-─╧╙ TAKES ABOUT
65 SECONDS, INCLUDING ABOUT 25 SECONDS OF "OVERHEAD" REQUIRED TO
DECODE AND RECODE THE ╨├-─╧╙ DIRECTORY AND FILE ALLOCATION TABLE (╞┴╘).
╬OTICE THAT ╔ SPECIFY THE CONVERSION OF A TEXT FILE.  ╘HIS BRINGS UP A
GENERAL CAVEAT: PROGRAM FILES WRITTEN TO RUN UNDER ╨├-─╧╙ (I.E. WITH A FILE
TYPE OF .┼╪┼ OR .├╧═) WILL NOT WORK IN ├-128 MODE OR ├╨/═ MODE (THE ├╨/═
EXECUTABLE FILE ALSO HAS A FILE TYPE OF .├╧═, BUT THE TWO ARE NOT
INTERCHANGEABLE) OR VICE VERSA.  ╚OWEVER, IF YOU DOWNLOAD A ├╨/═ PROGRAM TO
A ╨├-─╧╙ DISK AND THEN CONVERT THE FILE TO ├╨/═ FORMAT, THE PROGRAM WILL
WORK IN ├╨/═ MODE ON THE ├-128.  ╘HIS IS USEFUL, FOR EXAMPLE, IF YOU DO NOT
HAVE A MODEM ON YOUR ├-128 BUT HAVE ACCESS TO ONE ON AN ╔┬═-╨├ WHERE YOU
WORK.  ╘HE SAME GOES FOR DOWNLOADING TO A ├-128 PROGRAM TO ╨├-─╧╙ THEN
CONVERTING TO A ╨╥╟ ┴╙├╔╔ FILE OR DOWNLOADING TO ╙┼╤ FORMAT IN ├-128
MODE AND THEN CONVERTING TO ├╨/═ FORMAT.  (╘HE ORIGINAL ├╨/═ SYSTEM FILES
FOR THE ├-128 DID NOT SUPPORT A MODEM.  ╘HE UPGRADED VERSION NOW DOES.)
╘EXT AND DATA FILES, ON THE OTHER HAND, FROM ONE MACHINE CAN USUALLY BE
USED WITHOUT TROUBLE ON THE OTHER.  ╘EXT FILES TRANSFERRED USING SCREEN
CODE ╨╥╟ FILES MAY REQUIRE REFORMATTING ON THE TARGET WORD PROCESSOR.
╙CREEN CODE FILES WRITTEN BY ├╥╧╙╙ ╠╔╬╦ MAY NOT WORK WITH ALL ├-128
WORD PROCESSORS.  ╙OME WP'S, SUCH AS ╨APERBACK ╫RITER 128, INCLUDE A
HEADER BLOCK AT THE BEGINNING OF THE FILE.  ╘HE HEADER CONTAINS INFO
ON THE FILE CHARACTERISTICS SUCH AS MARGINS ETC.  ╔F IT IS NOT PRESENT,
THE WP MAY NOT BE ABLE TO READ THE FILE CORRECTLY.  ╘HESE WP'S CAN
USUALLY READ ╙┼╤ FILES AS WELL, HOWEVER, SO IT IS BETTER TO WRITE
A ╙┼╤ FILE WITH ├╥╧╙╙ ╠╔╬╦ FOR USE ON MOST WP'S.  ├╥╧╙╙ ╠╔╬╦ CAN
READ ╨╥╟ TEXT FILES WITH HEADERS, BUT YOU MUST DELETE THE HEADER BLOCK
WITH THE TARGET WP.

╠╔╙╘╔╬╟ 1 IS A ┬┴╙╔├ LOADER FOR THE MACHINE LANGUAGE PORTION OF THE
PROGRAM.  ╔T WILL CREATE A PROGRAM FILE NAMED "╪╠.═╠3" WHICH IS
AUTOMATICALLY LOADED BY THE MAIN PROGRAM.  ╘HE ═╠ ROUTINE, WHICH IS LOCATED
IN THE CASSETTE AND ╥╙ 232 BUFFERS, CONTAINS SEVERAL ENTRY POINTS.  ╘HESE
ARE:

    HEX     DEC               FUNCTION

   0B69    2921              BURST SECTOR READ (FOR ├╨/═ AND ╨├-─╧╙)
   0B9C    2972              READ ╙┼╤ OR ╨╥╟ FILE, NO CONVERT
   0BD0    3024              WRITE ╙┼╤, ╨╥╟ FILE OR PRINTER, NO CONVERT
   0C02    3074              BURST SECTOR WRITE (FOR ├╨/═ AND ╨├-─╧╙)
   0C45    3141              WRITE ╙┼╤ OR PRINTER , CONVERT ┴╙├╔╔ TO ╨┼╘╙├╔╔
   0CE0    3296              READ ╙┼╤ FILE, CONVERT ╨┼╘╙├╔╔ TO ┴╙├╔╔
   0D7D    3453              READ ╨╥╟ FILE, CONVERT SCREEN CODE TO ┴╙├╔╔
   0DDF    3551              WRITE ╨╥╟ FILE, CONVERT ┴╙├╔╔ TO SCREEN

╔F YOU ARE INTERESTED, YOU CAN DISASSEMBLE THE MACHINE LANGUAGE WITH
THE ├-128'S BUILT IN MONITOR.  ╘HE BURST MODE READ AND WRITE ROUTINES
ARE SIMILAR TO THOSE DESCRIBED IN PARTS 2 AND 3 OF THE ╘╨╒╟ SERIES.

╠╔╙╘╔╬╟ 2 IS THE MAIN ┬┴╙╔├ PROGRAM.  ┴S YOU CAN SEE, THERE ARE NO ╥┼═
STATEMENTS.  ┬ESIDE THE FACT THAT ╔ DON'T LIKE ╥┼═S (THEY CLUTTER UP THE
LISTING AND SERVE NO REAL PURPOSE ANYWAY), THEY ALSO TAKE UP A CONSIDERABLE
AMOUNT OF ╥┴═.  ╔N TRYING TO MAXIMIZE THE BUFFER SPACE, ╔ CHOSE TO LEAVE
THEM OUT.  ╞OR THE BENEFIT OF THOSE WHO ARE INTERESTED THE FOLLOWING
TABLE SUMMARIZES ITS MAIN PARTS.

     LINE                 FUNCTION

     10-80           OPENING DISPLAY, DEFAULT PARAMETERS, ETC.
     90-120          CALCULATE ├╨/═ SECTOR FILLING TABLE
     130-150         ─┬=START OF DIRECTORY BUFFER,
                     ╘┬=START OF DATA BUFFER IN BANK 0 ╥┴═
                     ─╓() AND ╘┘$() ARE THE SUPPORTED DEVICES
                     AND FILE TYPES.
     160             MAIN MENU SELECT
     170-200         READ ╙┼╤ OR ╨╥╟ FILE
     210-240         WRITE ╙┼╤ OR ╨╥╟ FILE OR PRINTER
     250-300         READ ├╨/═ FILE
     310-380         WRITE ├╨/═ FILE
     390             READ ╙┼╤ DIRECTORY
     400-420         READ ├╨/═ DIRECTORY
     440-450         READ A SPECIFIC ├╨/═ SECTOR
     460-470         WRITE A SPECIFIC ├╨/═ SECTOR
     480-540         ANALYZE ├╨/═ DIRECTORY AND ╞┴╘
     550-560         EXIT AND ERROR ROUTINES
     570             LOG IN CURRENT DISK
     580-600         READ ╨├-─╧╙ DIRECTORY
     610-620         READ A SPECIFIC ╨├-─╧╙ SECTOR
     630-650         ANALYZE ╨├-─╧╙ ╞┴╘ AND DIRECTORY
     660-720         READ ╨├-─╧╙ FILE
     730-770         WRITE ╨├-─╧╙ FILE
     780-820         RECODE AND WRITE ╨├-─╧╙ DIRECTORY AND ╞┴╘
     830-840         WRITE A SPECIFIC ╨├-─╧╙ SECTOR
     850             FIND FREE SPACE ON ╨├-─╧╙ DISK
     860-870         NORMALIZE ╨├ ─╧╙ AND ├╨/═ FILENAMES
     880             DISPLAY FILE STATS
     890-            ENTER MENU OPTIONS

╘HE MAXIMUM FILE SIZE THAT CAN BE TRANSFERRED IN ANY DIRECTIONS IS 45.5
K BYTES.  ╠ONGER FILES WILL BE TRUNCATED TO THIS LENGTH.  ╘HIS IS
EQUIVALENT TO 183 ╙┼╤ BLOCKS OR NEARLY 3 FULL ├╨/═ DIRECTORY EXTENTS.
┴LL FILES IN MEMORY ARE ASSUMED TO BE IN ┴╙├╔╔ FORMAT.  ╙┼╤ FILES READ
WITH THE CONVERSION OPTION ARE ASSUMED TO BE ╨┼╘╙├╔╔ ON THE DISK AND
ARE TRANSLATED TO ┴╙├╔╔ AS THEY ARE READ IN.  ╙┼╤ FILES WRITTEN
WITH THE CONVERSION OPTION ARE ASSUMED TO BE ┴╙├╔╔ IN MEMORY AND ARE
CONVERTED TO ╨┼╘╙├╔╔ AS THEY ARE WRITTEN TO DISK.  ╙IMILARLY, CONVERSIONS
ARE MADE WHEN READING FROM OR WRITING TO ╨╥╟ SCREEN CODE FILES.  ┴LL
OTHER TRANSFERS ARE DONE IN A BINARY WHAT-YOU-SEE-IS-WHAT-YOU-GET FASHION.

├╥╧╙╙ ╠╔╬╦ CAN BE USED FOR SIMPLE ┴╙├╔╔ <> ╨┼╘╙├╔╔ CONVERSION OF ╙┼╤
FILES WITH EITHER A 1571 OR 1541 (OR OTHER COMPATIBLE ) DRIVE IN THE
FOLLOWING MANNER:

     ╨┼╘╙├╔╔ TO ┴╙├╔╔ - READ THE FILE IN ╨┼╘╙├╔╔ <> ┴╙├╔╔ CONVERSION
                        MODE, THEN WRITE IT IN BINARY MODE.

     ┴╙├╔╔ TO ╨┼╘╙├╔╔ - READ THE FILE IN BINARY MODE, THEN WRITE IT IN
                        ╨┼╘╙├╔╔ <> ┴╙├╔╔ CONVERSION MODE.

╧NE WORD OF CAUTION FOR ╨┼╘╙├╔╔ <> ┴╙├╔╔ CONVERSIONS.  ├╥╧╙╙ ╠╔╬╦ PASSES
CONTROL CODES (┴╙├╔╔ VALUE LESS THAN 32) AND CERTAIN OTHER SPECIAL
CODES THROUGH IN BOTH DIRECTIONS UNCHANGED.  ╔T ALSO ADDS A LINEFEED
CHARACTER (┴╙├╔╔ ├╚╥$(10)) AFTER EACH CARRIAGE RETURN WHEN CONVERTING
TO ┴╙├╔╔ AND REMOVES ALL LINEFEEDS WHEN CONVERTING TO ╨┼╘╙├╔╔.  ╘HE
PRESENCE OF THESE CODES IN, FOR EXAMPLE, TEXT FORMATTED ON A ├╨/═
WORD PROCESSOR MAY REQUIRE THE TEXT TO BE REFORMATTED WITH A ├-128
WORD PROCESSOR BEFORE IT CAN BE USED IN ├-128 MODE.  ╔N ADDITION,
DOCUMENTS ORIGINALLY WRITTEN OR EDITED WITH SOME WORD PROCESSORS
(SUCH AS ╫ORD╙TAR- EITHER ├╨/═ OR ╨├-─╧╙ VERSION) SHOULD BE HANDLED
IN NON-DOCUMENT MODE (I.E. STANDARD ┴╙├╔╔) ON THESE WORD PROCESSORS
IF THEY ARE INTENDED TO BE SUBSEQUENTLY USED IN ├-128 MODE.  ╫ORD╙TAR
SETS THE HIGH BITS IN THE LAST CHARACTER OF EACH WORD IN DOCUMENT
MODE.  ╘HIS RESULTS IN AN INCORRECT ┴╙├╔╔ TO ╨┼╘╙├╔╔ CONVERSION.  ╘HE HIGH
BIT CAN ALSO BE STRIPPED OUT USING THE ┌ OPTION (ZERO THE PARITY BIT) OF
├╨/═'S ╨╔╨ COMMAND TO COPY THE ORIGINAL FILE TO AN ┴╙├╔╔ COMPATIBLE FILE.
┴ SIMILAR ROUTINE CAN BE USED FOR CONVERTING BETWEEN ╙┼╤ AND ╨╥╟ TEXT
FILES.

╫HEN READING THE DIRECTORY, ├╥╧╙╙ ╠╔╬╦ IGNORES THE FILE ATTRIBUTE (BYTE 11)
EXCEPT FOR THE VOLUME LABEL AND SUBDIRECTORY ATTRIBUTES WHICH DO NOT
REPRESENT VALID FILES.  ╘HUS YOU CAN DISPLAY AND ACCESS HIDDEN AND
SYSTEM FILES WHICH DO NOT SHOW UP ON AN ╔┬═-╨├ ─╔╥ COMMAND.
├╥╧╙╙ ╠╔╬╦ SETS DIRECTORY BYTES 11-25 AND 30-31 TO 0 WHEN IT IS WRITING A NEW
FILE.  ╘HIS IS EASIER THAN TRYING TO CALCULATE A FILE CREATION TIME, DATE,
ATTRIBUTE, ETC.  ┌ERO BYTES IN THESE LOCATIONS ARE ACCEPTED BY ╨├-─╧╙.  ╞OR
A MORE DETAILED DESCRIPTION OF ╨├-─╧╙ FILE FORMATS, ╨ART ╔ OF THIS ARTICLE.

├╥╧╙╙ ╠╔╬╦ WILL RECOVER UNUSED AND SCRATCHED DIRECTORY AND DATA SPACE FOR BOTH
├╨/═ AND ╨├-─╧╙ DISKS.  ╘HIS IS HANDLED AUTOMATICALLY BY ├OMMODORE ─╧╙ WHEN
WRITING TO ╙┼╤ FILES.  ├╥╧╙╙ ╠╔╬╦ IS CURRENTLY CONFIGURED TO WORK WITH
UP TO TWO DRIVES AND A PRINTER.  ╞OR ├╨/═ AND ╨├-─╧╙ FILES, AT LEAST ONE
OF THE DRIVES MUST BE A 1571.  ╘HE DEVICE CONFIGURATION CAN BE CHANGED
BY ALTERING THE DEFINITIONS OF ARRAYS ─╓() AND ─╓$() IN LINE 130-150.
╘O USE THE PRINTER FOR A FILE DUMP, SELECT ╙┼╤ ┴╙├╔╔ (FOR AN ┴╙├╔╔ PRINTER)
OR ╙┼╤ ╨┼╘╙├╔╔ AS THE TARGET FILE TYPE WITH THE "╙┼╘ ╘┴╥╟┼╘" OPTION
ON THE MAIN MENU.  (╘HERE IS NO NEED TO SPECIFY A FILENAME FOR THE
PRINTER. ┴ <RETURN> AT THE FILENAME PROMPT IS SUFFICIENT.) ┘OU CAN THEN
SELECT THE PRINTER AS THE TARGET DEVICE.   ╧F COURSE, THE 1541 OR
COMPATIBLE CAN ONLY BE USED TO READ OR WRITE ╙┼╤ FILES, SINCE IT DOES
NOT SUPPORT BURST MODE.

┴LTHOUGH IT IS NOT AN ╔┬═-╨├ EMULATOR, YOU WILL FIND ├╥╧╙╙ ╠╔╬╦ AN INVALUABLE
UTILITY FOR TRANSFERRING FILES FROM ONE MACHINE TO ANOTHER (AND BETWEEN
MODES ON THE ├-128 ALSO) IF YOU USE BOTH AN ╔┬═-╨├ AND A ├-128.  ╔T IS ALSO
POSSIBLE WITH A LITTLE DETAILED KNOWLEDGE OF THE DISK FORMATS TO USE THE
SAME PRINCIPLES FOR TRANSFERRING FILES TO/FROM OTHER COMPUTERS AND
OPERATING SYSTEMS THAT USE ═╞═ TYPE DISKS, SUCH AS ╘╥╙─╧╙ USED ON THE
╥ADIO ╙HACK COMPUTERS OR POSSIBLY ╥╙ ├O├O ╧╙/9 DISKS TO ╨┼╘ ╧╙/9 FORMAT.

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