Appendix JFILE HEADER INFORMATIONJ.1 Character Set Header All files with the extension .CHR are Character Set table files. These files contain data corresponding to the actual dot matrix displayed for each character on the console. These files also contain information regarding the character set name, version number, origin, date of creation, and display class. The Character Set table file header is a 128 byte field, structured as follows: Byte No. Function
Hex Dec
00 00 Character Set type, ASCII 'C'=character
01 01 Character Set Version No. (ASCII 0
through 9)
02-0D 02-13 Display Class
0E-15 14-21 Character Set Name
16 22 Filler (ASCII Space)
17-19 23-25 Banner Class
1A 26 Filler (ASCII Space)
1B-3D 27-61 Comment
3E-4D 62-77 Originator
4E-55 78-55 Creation Date - arranged as YY/MM/DD
56-59 86-89 Number of records in the file in ASCII.
A character set file of 128 characters
has 32 records; a character set file of
256 characters has 64 records. The
record count for a 32 record file is
stored as 30 30 33 32 (0032)
5A-5B 90-91 Reserved
5C 92 This byte is used to house three
variables. Bit 7 is used to show the
Horizontal/Vertical alignment of the
character set - bit 7 ON infers a
Vertical character set. Bits 6 through
4 of the high nibble is used to store
the binary Super/Subscript value (which
may be 1 through 7) offset from 1 - thus
a Super/Subscript value of two would be
stored as binary 2. The low nibble is
used to store the binary Character
Height offset from 0 - thus a Character
Height value of 16 would be stored as
binary F. The Character height is a
function of the number of vertical
pixels the character will occupy in the
16x10 pixel matrix available for each
character on the screen.
If the Horizontal/Vertical bit, the
Super/Subscript value and the Character
Height value was as stated above, then
this byte would read AF. The byte
appears:
Bit [7] [ 6 5 4 ] [ 3 2 1 0 ]
Function Horiz/Vert Super/Sub Character
Height
5D 93 This byte contains two values; the
User/System character set toggle, bit 0
stores this value; and the Stock/Special
character set toggle, bit 1 stores this
value. Bit 0 ON infers that the
character set is a special character
set.
5E 94 This byte contains information on the
character set width. If the high nibble
is 0, then the low nibble contains the
binary information, offset from 0, of
all the characters in the character set
- thus a character set width value of 16
would be stored as F. If the high
nibble is F, then the character set is a
proportional one - the proportional
character set has a trailing record
containing information on the width of
each individual character in the
character set. A proportional character
set is designed to be used in high-
resolution mode as it requires a 16x16
screen cell.
5F-7F 95-127 Reserved.
80- 128- The character set font information.
J.1.1 Sample Character Set Table File Header
Following is an actual header taken from the Character Set table file for the character set PROP.CHR. PROP contains 128 characters, and is a proportional character set: Hex Offset Value in Hex
0: 43 30 49 6E 74 27 6C 20 20 20 20 20 20 20 50 52
10: 4F 50 20 20 20 20 20 43 48 52 20 54 68 69 6E 20
20: 70 72 6F 70 6F 72 74 69 6F 6E 61 6C 20 63 68 61
30: 72 61 63 74 65 72 20 73 65 74 20 20 20 20 53 69
40: 72 69 75 73 20 53 79 73 74 65 6D 73 20 20 38 32
50: 2F 30 37 2F 31 36 30 30 33 30 00 00 7F 00 FF 00
60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
J.2 Proportional Character Set Trailer Information
In the case of a proportional character set, the trailing 128 bytes of the character set file contains information on the proportional width of each of the characters in the file. A proportional character set may not, therefore, contain more than 256 characters. The following is a sample taken from the character set PROP.CHR; the hex figures represent the width for each proportional character starting with the space character. Note that each width value is offset from 0, with a value range of 1 through 16 decimal. Each byte is stored, and represented below, in low/high order; the two nibbles would be exchanged to give the value to the character(s) in high/low order. Each character is mapped from the proportional width as follows: 29 95 98 49 77 88 84 93 The above figures are for the first 16 display characters including the space character - they correspond as follows: space = 10 (corresponding to 9)
! = 3 (corresponding to 2)
" = 6 (corresponding to 5)
# = 10 (corresponding to 9)
$ = 9 (corresponding to 8)
% = 10 (corresponding to 9)
& = 10 (corresponding to 9)
' = 5 (corresponding to 4)
( = 8 (corresponding to 7)
) = 8 (corresponding to 7)
* = 9 (corresponding to 8)
etc.
J.3 Keyboard Table Header
All files with the extension .KB are Keyboard Table files. these files contain information regarding keyboard code generated when a key on the keyboard is pressed. These files also contain information regarding the Keyboard Table name, version number, origin, date of creation, and display class. The Keyboard Table table file header is a 128 byte field, structured as follows: Byte No. Function
Hex Dec
00 00 Keyboard table type, ASCII 'K'=character
01 01 Keyboard table Version No. (ASCII 0
through 9)
02-0D 02-13 Display Class
0E-15 14-21 Keyboard Table Name
16 22 Filler (ASCII Space)
17-19 23-25 Banner Class
1A 26 Filler (ASCII Space)
1B-3D 27-61 Comment
3E-4D 62-77 Originator
4E-55 78-55 Creation Date - arranged as YY/MM/DD
56-59 86-89 Number of records in the file in ASCII.
A character set file of 128 characters
has 32 records; a character set file of
256 characters has 64 records. The
record count for a 32 record file is
stored as 30 30 33 32 (0032)
5A-7F 90-127 Reserved
80- 128- Keyboard table information
J.4 Banner Skeleton Files
Files with the extension .BAN are banner skeleton files. The banner is information printed on the screen during system boot. The banner also prints the Logo (if selected) along with other information regarding configuration. The banner is a set of ASCII strings containing the escape sequences and characters necessary to print the logo and configuration information on the console. The first 128 bytes of the Banner Skeleton has the following format. The first byte is zero followed by 0Dh, 0Ah. This is followed by the length of the file in ASCII decimal with a leading and trailing space, and followed by 0Dh, 0Ah. The location of the keyboard name and character set name follow in the same format as the file name length. If the file length is 639 characters, the keyboard name is at byte 502, and the character set name is at 541, then the first 24 bytes of the banner file would be as follows: 30 0D 0A 20 36 33 39 20 0D 0A 20 35 30 32 20 0D 0A 20
Would you like your company name included on the Sirius banner? Syselect permits the selection to be made, but first you need to create a banner. This may be achieved by using ED (under CP/M-86), EDLIN (under MS-DOS) or WordStar. 1. CP/M-86 A>PIP YOUR.BAN=SIRIUS.BAN Syselect may now be used to include your banner file in an operating system. J.6 This paragraph has been omitted J.7 Normal File Control BlockThe normal file control block is structured as follows - with offsets in decimal: Byte Contents
0 The drive number. The drives are numbered as
follows:
Before opening file: 0 = default drive
1 = drive A
2 = drive B
3 = drive C, etc.
After opening file: 1 = drive A
2 = drive B, etc.
MS-DOS replaces the default drive prefix of 0
with the correct drive number after the open
is processed.
1-8 Filename, left justified with trailing ASCII
space(s). If a device name is placed in this
region, the trailing colon should be omitted.
9-11 Extent, left justified with trailing ASCII
space(s).
12-13 Current block number relative to the
beginning of the file, starting with zero
(automatically set to zero by the open
function request). A block consists of 128
records, each record being of the size
specified in the logical record size field.
The current block number is used with the
current record field for sequential
reads/writes.
14-15 Logical record size in bytes. Set to 80H by
the open function request.
16-19 File size in bytes. The first word
represents the low-order part of the file
size.
20-21 Date the file was created or last updated.
The date is set by the open function request.
The date is formatted as follows:
< 21 > < 20 >
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
y y y y y y y m m m m d d d d d
where m = month 1-12
d = day 1-31
y = year 0-119 (1980 - 2099)
22-23 Time the file was created or last updated.
The time is set by the open function request.
The time is formatted as follows:
< 23 > < 22 >
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
h h h h h m m m m m m s s s s s
where h = hours 0-23
m = minutes 0-59
s = seconds*2 0-59
24-31 Reserved for system use.
32 Current relative record number (0-127) within
the current block. This must be set before
doing sequential read/write operations on the
file. The open function request does not set
this field.
33-36 Relative record number, relative to the
origin of the file, starting at zero. This
field must be set prior to doing random
read/write operations on the file. The open
function request does not set this field.
If the record size is less than 64 bytes,
both words are used. If the record size is
greater than 64 bytes, then only the first
three bytes are used.
Notes: The File Control Block at 5CH in the Base Page overlaps both the File Control Block at 6CH and the first byte of the command line area/disc transfer area at 80H. Bytes 0 - 15 and 32 - 36 must be set by the user program. Bytes 16 - 31 are set by MS-DOS and may only be changed at the programmers own risk. In the 8086/8088 all word fields are stored least significant byte first - this is true in setting the record length, etc. J.8 Extended File Control BlockThe extended FCB is used to create or search for files having special attributes. The extended FCB adds an additional 7 bytes preceeding the normal FCB. The extended FCB is structured as follows: Byte Contents
FCB-7 Set to FFH indicates that an extended FCB is
being used.
FCB-6 - FCB-2 Are reserved.
FCB-1 Attribute byte to include hidden files (02H)
or system files (04H) in directory searches.
FCB-0 Origin of normal FCB (drive byte).
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