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NULUMOD.DOC
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1987-12-16
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142 lines
NULU MODIFICATION
This is an update to Martins original documentation. It details
which locations to patch to install NULU. These have been updated
as part of the modification process to create NULU 1.52.
Patches are listed in the order in which they appear in NULU.COM.
Each patch is explained and the default values are listed
immediately next to the patch address. All addresses are
absolute hexadecimal.
Patch Default Explanation
00194h 50h Number of characters each full
video line can contain. Not
necessarily the same as the number
you can see.
00195h 50h Number of characters visible on a
line at any one time.
00198h 07h This byte indicates the number of
files that NULU can have open at
any one time. The base number is
4 and should never fall below that.
The value of 3 has been added to it
to allow 3 level nesting of NCF
files. If the NCF value is
increased or decreased, identical
changes should be made to this
byte. (See Patch at 00251h.)
00199h 0010h This obscure word controls the
number of relocatable tasks that
can be controlled by the NULU
memory management routines.
Because each file is a relocatable
task, the same modifications for
the previous byte apply here. The
base value of this word is 000dh
and should never fall below that
point. (See Patch at 00251h.)
0019bh 10h Number of contiguously numbered
disk drives in your system. If you
have drives A and B, set this value
to 2. It will prevent you from
accessing an invalid drive.
0019ch 10h Number of contiguous user areas
that NULU will be allowed to
access. Under normal CP/M 2.2,
Turbo-Dos or a ZCPR system, I
understand that this number can be
as high as 20h. For CP/M Plus or
most systems that use time/date
stamping this number should not
exceed 10h.
001cdh 0005h This is the address of the BDOS
vector. All operating system calls
go through this address. If you
have some weird, non-standard CP/M
implementation you can patch this
to try to make NULU work with it.
0024dh 00h Set to a non-zero value to make
NULU READ/ONLY. No operators will
be executed that could change the
library or disk directories in any
way.
0024eh 00h LU.COM was set up to exit
automatically if a command tail was
used when LU was invoked. With the
release version of NULU, it takes
the -X command to exit. Set this
byte to a 01h to get it to act like
LU in this respect. That is, it
will automatically exit after
executing the passed command tail,
if one was present.
0024fh 01h Set to a 00h to start NULU with
BRIEF mode ON (long messages not
printed).
00250h 01h Set to zero to prevent users from
being able to ESC,RET from the
PROMPT AND CHAIN TO PREVIOUS MODE
prompts in NCF files. (Be sure to
also change the values at 00198h
and 00199h.)
00251h 03h This byte indicates the nesting
level allowed for NCF files. I
have no idea what the upper limit
is, but watch that Data Buffer
Size!
00252h '-Y *LBR -O',0 Starting here are 39 bytes in which
any valid NULU operators may be
stored. This line will be
automatically executed when NULU is
loaded, even before any other
parameters passed on the command
line. This might be used to create
a version of NULU that, after
loading, sets the drive/user
defaults to B0:, prints the menu,
scans the drive for library files,
then switches to the open library
mode. That command line would look
like this:
-U B: -H -Y *LBR -O
Notice that all characters in this
line MUST be UPPER CASE. The
entire line MUST be terminated by a
null byte. Only 39 bytes are
available for text...not a byte
more. The 40th byte is for the
null terminator.
002a0h 3ch This is the number of lines that
NULU will print on each page during
member file printing. Change this
value in accordance with the line
printer patch below. Set it to
zero to have NULU ignore line
counts altogether.
Starting at 0027dh are 5 data areas used to define strings needed
to control the console attributes. Each string is preceded by an
identification byte and a byte indicating its active length.
Then 5 bytes are available for the actual definition. Therefore
a total of 7 bytes is consumed for each video control. The
attributes are, in order:
DIM or REVERSE VIDEO ON (DIM is preferred)
DIM or REVERSE VIDEO OFF
UNDERLINING ON
UNDERLINING OFF
CLEAR SCREEN
Each control becomes active as soon as it is patched in.
Likewise, there is one string defined for the LST: device that
will be issued immediately before printing a file. It begins at
002a2h and has the same format as the strings above.