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DU-V86.DOC
----------
By Ward Christensen (revised 10/18/83)
additional notes by Ron Fowler, Irv Hoff, and Jeffrey Nonken
; This version of DU is compatible with CP/M 1.4, 2.x and 3.x and does
; not require alteration for various hardware configurations. It ad-
; justs itself automatically to the correct number of sectors, tracks,
; directory size, etc.
;
INDEX
1.0 INSTALLATION:
2.0 USE:
2.1 COMMANDS, BY FUNCTION
2.2 ALPHABETIC COMMAND SUMMARY
3.0 NOTES
4.0 INTERPRETATING DIRECTORY DATA
4.1 SINGLE DENSITY
4.2 DOUBLE DENSITY
1.0 INSTALLATION:
===
Because of the automatic adaption feature, no conditional assem-
bly options are included. The only alteration that needs to be done is
to use DDT to set the byte at 103H for your clock speed. Use 0 for 2MHz,
1 for 4MHz, 2 for 6MHz. (This only affects the 'Z' SLEEP command.)
2.0 USE:
===
An initial command string may optionally be placed as an operand
of the original 'DU' command, i.e.:
A>DU G0;D;G2;=OK<D><A><1A>;D
for example, if you want to only map the disk, and then exit:
A>DUU M;X
Once 'DU' is running, it expects single-letter commands much
like 'SID' OR 'DDT'. For ease of use, multiple commands may be placed
on one line, separated by ";". In addition, a given command or string
of commands may be repeated -- either indefinitely (until ^C is pressed)
or a given number of times.
To avoid an accidental ^C from dropping out of 'DU', only an ex-
plicit "X" command will exit 'DU'.
2.1 COMMANDS, BY FUNCTION
===
HELP:
? displays the help guide
POSITIONING:
Gnn by allocation group
Snn by sector
Tnn by track
+nn going ahead nn sectors
-nn going back nn sectors
I/O:
< puts current sector "away" into a buffer
> recalls previously saved sector
K writes "yanked" sectors to a file
(see "saving sequential memory" in notes below)
R reads sector
W writes sector
Y "yanks" current sector into sequential memory
DISPLAYING:
# shows disk parameters
A dump sector in ASCII
D dump the sector (hex + ASCII)
G shows current group, track, sector
H dump sector in hex
M maps the disk -- where the files are located
Mxx map starting at group xx
Vnn views (like CP/M type) nn sectors
CHANGING:
CAnn,VAL change data in ASCII (with <xx> escape to hex)
CHnn,VAL change data in hex
Unn change user to nn
SEARCHING:
=Abc scan for Abc (IN ASCII) from current sector on (very
slow, allow up to 15 minutes to scan an entire disk.
Either finds the answer or says: "out of bounds".
FNAME find a file in the directory
F find next occurrence (extent) of same name
MISC:
( toggles the map display to show/not show erased files
/nn repeat previous command nn times (repeats indefinitely
if nn omitted)
Bnn boot nn sectors per track
LX log in disk X
P printer toggle
Q before a command does it 'quietly'
X exit to CP/M
Znn sleep (nn tenths of a second) to allow viewing data
before it scrolls off
2.2 ALPHABETIC COMMAND SUMMARY
===
# PRINTS THE DISK PARAMETERS
+ Advance 1 sector (if below track 2, this advances to
next numerical, if 2 or more, advances based on
CP/M's normal sector scrambling algorithm, i.e.,
allows + to the next logical sector of the file.
- backs up 1 logical sector
NOTE: + and - may take an amount: For example,
+15 advances 15 sectors
/ repeats entire command -- defaults to "forever"
/nn nn may be 2 TO 65535
( toggles the map display to show/not show erased files.
When showing erased files '*' indicates that block
duplicates a block in another file. It may not be
possible to restore this program without errors. If
there are no '*' in this complete file, it can be
correctly restored.
< saves current sector in a 'save' buffer
=Abc ASCII search, starting at current sector. <xx> hex
may be imbedded or used alone. To find: "IN 0FEH"
use: =<DB><FE> (Ignores bit 7 unless using <xx>.)
Since ";" is a command delimiter, you have to use
<3B> to search for a ";". Also, since "<" is a hex
escape character, use << to mean a single "<".
NOTE: This is a very slow routine. It can take 15
minutes or longer to search an entire double-
density double-sided disk so be patient. It
either finds the string or says: "OUT OF
BOUNDS".
> gets saved buffer. < and > maybe be used to move
a sector to another place.
? displays the help guide
A dump sector (ASCII only)
Bnn boot nn sectors per track -- not all disks have 26.
CHADDR,VAL,VAL,VAL... change hex values in sector
CAADDR,CHAR STRING... change ASCII calues in sector
NOTE: <xx> may be hex imbedded in the ASCII
string: CA00,OK<0D><0A><1A>
----> W writes changes to disk
note that the 'C' command echoes the over-
laid data for verification.
CHADDR-ADDR,BYTE repeats a change
CAADDR-ADDR,BYTE repeats a change
D dump sector (hex + ASCII)
FNAME print directory for file "NAME", then positions to
its directory sector.
F find next occurrence of name in directory
Gnn position to group nn and read
G shows current position
H dump sector, hex only
Kdu:filename.ext save a file from "yanked" sectors.
drive, user are optional. Resets "yank" address.
see "saving sequential memory" in notes below.
L re-logs in the current disk -- you may pull out a
disk, put in a new one, and "L" just to log it in.
(see "logging in disk" in notes below)
LX logs in disk 'X', such as: LB, LC, LA, etc.
M dumps a map of the group allocations for files
Mn shows which file is allocated to group "N"
N resets CP/M via BDOS -- this may make it possible under
some implementations of CP/M to change the disk
format, i.e., density, sides, etc.
P toggles the printer on/off
Q quiet -- preceedintg any command, suppresses CRT output
R reads into memory the sector currently positioned at.
NOTE: 'R' (read) is implicit in the G, +, and -
commands but NOT in the 'S' and 'T' commands
Snn position to sector nn, and read
TNN seek to track nn (no read)
Ux logs user 'x' for next 'F' command
V views the current sector -- assumes ASCII data
Vnn views nn sectors
W writes the current sector to disk
NOTE: may NOT be used after an 'F' command as
CP/M was used to find file in the directory
X exit back to CP/M (must press return). ^C was too
easy to hit over modem lines -- requires two bytes:
(X,CR) to exit.
Y "yank" the current sector into sequential memory
(starts at 3000H, increments for each yank)
Z sleep -- causes the porgram to pause -- such as to look
at a dump. Z is 1 second
Znn nn tenths of a second Z50 = 5 seconds
3.0 NOTES
===
* Multiple commands: May be separated by ";"
EXAMPLE: The following commands will erase the B: disk directory to all
E5's:
LB log in B: drive
G0 position to directory
CH0-7F,E5 fill with E5
< save the sector
>;W;+;/16 restore, write, next, repeat 16
---- this could be shortened to:
LB;G0;CH0-7F,E5;<
>;W;+;/16
* DUMP COMMANDS: All dump commands (D, A, H) may be optionally followed
by a starting and ending address:
D0,7F the same as just 'D'
D3,5
A20,3F
* LOGGING IN DISK: If you have a disk with a 'blown directory', try
logging in a good disk of the same density, then put in the 'blown' disk
without logging it in. You are opening yourself to possible problems
because of the buffering of physical sectors in the 'BIOS'. The best
technique, (but not guaranteed), would be to seek to the unused inner
tracks of the first disk, do the read, then change disks. That way, if
it write anything, you won't have destroyed anything -- assuming the
disk is not completely full. Another technique (assuming the second
disk does not contain a CP/M system, would be to seek to track 1, do the
read there, then change disks to the blown one.
* SAVING SEQUENTIAL MEMORY:
Since CP/M v 3.0 does not have a SAVE function, one has been added.
Syntax is:
Kdu:filename.ext
^^^ ^ ^
øøø ø +-- file extension (0-3 characters)
øøø +-------- file name (1-8 characters)
øø+--------------- user # (or none)
ø+---------------- drive designation (A-P or none)
+----------------- DU command
Drive and user may be omitted. If so, omit the colon as well. Drive
must be specified if the user is. If the user # is omitted, the current
user is used. If the drive is omitted, the current CP/M default drive
is used.
This function saves the current contents of sequential memory into a disk
file. The contents of sequential memory are determined by the 'yank'
function, and the pointer of that function is used here. If nothing has
been yanked, you get an error. Once the file has been saved, the 'yank'
pointer is re-initialized to its original value (3000H). Control is re-
turned to DU.
4.0 INTERPRETATING DIRECTORY DATA
===
4.1 SINGLE DENSITY
===
The following explains the format of a CP/M directory entry as
shown by 'DU', using either the 'F' (find file) command, or just doing
'D' (dump) of the directory sectors, which are located in groups 0 and 1
on a single-density disk.
SAMPLE RESULT OF 'FSID.COM' COMMAND:
40 00534944 20202020 20434F4D 0000003A *.SID COM...:*
50 33343536 3738393A 00000000 00000000 *3456789:........*
FIRST LINE -
40 00534944 20202020 20434F4D 0000003A *.SID COM...:*
øø øøø ø øø øø ø ø
øø øø^---hex file name/type--^ øø øø ^file name^
øø øø øø øø in ASCII
øø øø extent-^^ øø
øø øø øø
øø øø file size in sectors-^^
øø øø
øø ^^-00 = file active other values (E.G 03) = user #
øø E5 = file erased
^^-displacement of line in directory sector
SECOND LINE -
50 33343536 3738393A 00000000 00000000 *3456789:........*
ø ø ø
ø ø ^- allocation groups
^-----allocation group numbers-----^ (just happened to
be printable)
4.2 DOUBLE DENSITY
===
The following is a sample of 'FSID.COM' running on a double-
density system:
:FSID.COM
00 00534944 20202020 20434F4D 0000003A *.SID COM...:*
10 38003900 3A003B00 00000000 00000000 *8.9.:.;.........*
G=0000:00, T=2, S=1, PS=0
The primary difference is that the groups now occupy 2 bytes,
i.e., 38 00" "39 00" ... this follows the Intel and CP/M convention of
putting 16-bit values high-byte-first. This it means group 0038, 0039
etc.
Note that in double-density, each group stood for 2k not 1K,
so there were half as many groups for the same file.
Be very careful when patching a directory under double-density.
For exmaple:
CH10,38,39,3A,3B...
This might try to access group 3938 with resultant angry noise
from the disk stepper as it attempts to find where it should go for the
data.
* * * * *
«eof»