System information

E Ends the edit. Copy all buffered text to temporary file and copy all unprocessed
source lines to temporary file. Rename files.
H Moves to head of new file by performing automatic E command. The temporary
file becomes the new source file, the memory buffer is emptied, and a new
temporary file is created. The effect is equivalent to issuing an E
command, followed by a reinvocation of ED, using x.y as the file to edit.
O Returns to original file. The memory buffer is emptied, the temporary file is
deleted, and the SP is returned to position 1 of the source file. The effects of the
previous editing commands are thus nullified.
Q Quits edit with no file alterations, returns to CP/M.
There are a number of special cases to consider. If the integer n is omitted in any ED command
where an integer is allowed, then 1 is assumed. Thus, the commands A and W append one line
and write one line, respectively. In addition, if a pound sign # is given in the place of n, then the
integer 65535 is assumed (the largest value for n that is allowed). Because most source files can
be contained entirely in the memory buffer, the command #A is often issued at the beginning of
the edit to read the entire source file to memory. Similarly, the command #W writes the entire
buffer to the temporary file.
Two special forms of the A and W commands are provided as a convenience. The command OA
fills the current memory buffer at least half full, while OW writes lines until the buffer is at least
half empty. An error is issued if the memory buffer size is exceeded. You can then enter any
command, such as W, that does not increase memory requirements. The remainder of any partial
line read during the overflow will be brought into memory on the next successful append.
2.1.3 Memory Buffer Organization
The memory buffer can be considered a sequence of source lines brought in with the A command
from a source file. The memory buffer has an imaginary character pointer (CP) that moves
throughout the memory buffer under command of the operator.
2.1 Introduction to ED CP/M Operating System Manual
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