blank.gif (43 bytes)

Church Of The
Swimming Elephant




Using the debug command without specifying a file to be tested

If you use the debug command without a location and filename, you then type all Debug commands in response to the Debug prompt, a hyphen (-).

Debug commands

The following is a list of Debug commands.

Displays a list of the Debug commands.
Assembles 8086/8087/8088 mnemonics.
Compares two portions of memory.
Displays the contents of a portion of memory.
Enters data into memory starting at a specified address.
Fills a range of memory with specified values.
Runs the executable file that is in memory.
Performs hexadecimal arithmetic.
Displays one byte value from a specified port.
Loads the contents of a file or disk sectors into memory.
Copies the contents of a block of memory.
Specifies a file for an l or w command, or specifies the parameters for the file you are testing.
Sends one byte value to an output port.
Executes a loop, a repeated string instruction, a software interrupt, or a subroutine.
Stops the Debug session.
Displays or alters the contents of one or more registers.
Searches a portion of memory for a specified pattern of one or more byte values.
Executes one instruction and then displays the contents of all registers, the status of all flags, and the decoded form of the instruction that Debug will execute next.
Disassembles bytes and displays the corresponding source statements.
Writes the file being tested to a disk.
Allocates expanded memory.
Deallocates expanded memory.
Maps expanded memory pages.
Displays the status of expanded memory.

Separating command parameters

All Debug commands accept parameters, except the q command. You can separate parameters with commas or spaces, but these separators are required only between two hexadecimal values. Therefore, the following commands are equivalent:

dcs:100 110

d cs:100 110


Specifying valid address entries

An address parameter in a Debug command specifies a location in memory. Address is a two-part designation containing either an alphabetic segment register or a 4-digit segment address, plus an offset value. You can omit the segment register or segment address. The default segment for the a, g, l, t, u, and w commands is CS. The default segment for all other commands is DS. All numeric values are in hexadecimal format.

The following are valid addresses:



The colon between the segment name and the offset value is required.

Specifying valid range entries

A range parameter in a Debug command specifies a range of memory. You can choose from two formats for range: a starting address and an ending address, or a starting address and the length (denoted by l) of the range.

For example, both of the following syntaxes specify a 16-byte range beginning at CS:100:

cs:100 10f

cs:100 l 10

More Information About Debug

ntcmds00000001.gif Debug Commands

ntcmds00000001.gif Debug


Protect yourself from cyberstalkers, identity thieves, and those who would snoop on you.
Stop spam from invading your inbox without losing the mail you want. We give you more control over your e-mail than any other service.
Block popups, ads, and malicious scripts while you surf the net through our anonymous proxies.
Participate in Usenet, host your web files, easily send anonymous messages, and more, much more.
All private, all encrypted, all secure, all in an easy to use service, and all for only $5.95 a month!

Service Details

Have you gone to church today?
All pages ©1999, 2000, 2001, 2002, 2003 Church of the Swimming Elephant unless otherwise stated
Church of the Swimming Elephant©1999, 2000, 2001, 2002, 2003 is a wholly owned subsidiary of Packetderm, LLC.

Packetderm, LLC
210 Park Ave #308
Worcester, MA 01609