System information

4.2.2 The D (Display) Command
The D command allows you to view the contents of memory in hexadecimal and ASCII formats.
The D command takes the forms:
D
Ds
Ds,f
In the first form, memory is displayed from the current display address, initially 100H, and
continues for 16 display lines. Each display line takes the followng form:
aaaa bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb cccccccccccccccc
where aaaa is the display address in hexadecimal and bb represents data present in memory
starting at aaaa. The ASCII characters starting at aaaa are to the right (represented by the
sequence of character c) where nongraphic characters are printed as a period. You should note
that both upper- and lower-case alphabetics are displayed, and will appear as upper-case symbols
on a console device that supports only upper-case. Each display line gives the values of 16 bytes
of data, with the first line truncated so that the next line begins at an address that is a multiple of
16.
The second form of the D command is similar to the first, except that the display address is first
set to address s.
The third form causes the display to continue from address s through address f. In all cases, the
display address is set to the first address not displayed in this command, so that a continuing
display can be accomplished by issuing successive D commands with no explicit addresses.
Excessively long displays can be aborted by pressing the return key.
4.2.3 The F (Fill) Command
The F command takes the form:
Fs,f,c
where s is the starting address, f is the final address, and c is a hexadecimal byte constant. DDT
stores the constant c at address s, increments the value of s and test against f. If s exceeds f, the
operation terminates, otherwise the operation is repeated. Thus, the fill command can be used to
set a memory block to a specific constant value.
4.2 DDT Commands CP/M Operating System Manual
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