26.1 Purpose
The FIX program can be used to modify bytes of DOS-Ioadable object code in an absolute code file. This program can be very dangerous and should be used only by qualified assembler language programmers or by someone following specific directions provided by Datapoint.
26.2 Use
To invoke FIX, enter the command:
FIX <file spec)
The program will display a sign-on message and will then display an initial line of six zeros, two spaces, and three more zeros on the bottom CRT line. (The zeros represent the current address and its contents.)
000000 000
The screen is then rolled up. The program then waits for a command from the operator. The <file spec) must specify a
DOS-Ioadable object file. If no extension is provided, lABS is assumed.
Commands are 'in the form [number] [character] where the number is assumed to be octal. If the number is omitted, a value of zero is used. Commands are terminated by the enter key. Following a command, the current address and its contents are re-displayed.
26.3 Commands
The following is a list of command characters with their effect:
ENTER - Set current address.
- If no block of object code is currently in
memory {as at the beginning of execution or after a block has been rewritten), search the object file forward until"
a block containing the given location is found, then display the contents of that location. If the address does not exist in the object file, the current address is
I eft at zero.
- If a block of code is in memory and the location given is within the limits of the block, the contents of the
location will be displayed.
If a block is in memory and the location given is not within the block limits, the current address will be set to the minimum or maximum address of that block, its contents will be displayed and a beep will sound. To access the desired address the current block must first be aborted (A) or transferred (T).
M - Change the contents of the current address to the number given.
I - Increment the current address (up to the maximum address in the current block).
- Change contents of current address to number given and automatically increment the current address and display the contents of the resulting location.
D Decrement the current address (down to the minimum address in the current block).
T - Transfer the modified block back to disk - rewriting it in place. After the block is written, the current
address is set back to zero, so that all searches always start" from the beginning of the file. No modification is made to the stored file until a T command is executed.
A - Abort processing the current block, set the current address back to zero.
o
or* -
Return to the operating system - if there is a block of object code in memory, it is not written back into the file.If the command character is not one of the above, it is ignored and regarded as if only the ENTER KEY had been pressed.
26-2 DISK OPERATING SYSTEM
26.4 Error Messages
If the <filespec) is not an absolute object code file, the message
RECORD FO RMAT ERRO R
is displayed.
If the file specified on the command line is not found, the message
NO SUCH NAME
is displayed.
CHAPTER 27. FIXAPPLY
27.1 Purpose
FIXAPPLY is a program which accepts as input patch files distributed by Datapoint Corporation for software maintenance purposes. Each encoded patch file contains the file names and member names of the modules to be patched, the patch addresses, patch data, and generated self-checking bytes to guarantee file integrity.
27.2 Use
FIXAPPLY is invoked using a command line of the form:
FIXAPPLY <patchfile)
where <patch file) specifies the name of the patch file containing the modifications to be performed. All information needed for the modifications to be perftirmed is included in the patch file,
including the names of the files and library members involved.
FIXAPPLY execution consists of two phases: a verification phase and an execution phase. The verification phase reads the input patch file, locates all modules to be patched, verifies the prior data to be overstored, and guarantees the self-check fields to be correct. The execution phase reads a binary work file
generated in the first phase and directly updates the object modules.
27.2.1 FIXAPPLY Phase One
The first phase of FIXAPPLY reads the patch file provided, converts the data into binary, validates it, and builds a wo~k
file on disk (FIXAPPLY/WRK) containing the random positions in the programs to be patched.
If any errors are found in the first phase, execution is _ terminated (with one exception, as described below). Note that
the original value of the object byte to be patched is contained as part of the data in the patch file. This data must match,
CHAPTER 27. FIXAPPLY 27-1
preventing re-patching the same object module. It also allows version and revisi9n levels to be checked.
Most errors occuring in phase one allow phase one to run to completion but will not allow phase two to run.
There is one phase one error which can be overridden by
operator intervention at the s~stem console. If FIXAPPLY fails to find a particular file, the message:
CAN'T FIND FILE <file name>
will be displayed. The operator will then be asked for the correct name of this file. This action allows users who have renamed Datapoint software prod~cts to specify their own in-house names. Member names within absolute libraries, however, cannot be overridden.
If fatal phase one errors are found, the message: