Epson PX-8 User Manual page 37

screen has been set. The CONFIG program described in Chapter 3 can be used
to check this and reset it if necessary.
Go to the System Display and switch off the MENU. Exit from the System Dis-
play to display the CP
1M
command line.
If
the screen is not clear, it may be cleared by pressing the
I
CLR
I
key
(I
SHIFT
I
+[QKJ), or typing CTRL-L by holding down the
I
CTRL
I
key while pressing
the "[!J" key. In either case the display will show "I\L"next to the
CP/M
sys-
tem prompt. Thus if the currently logged in drive is A:, the following will be
displayed:
When the
I
RETURN
I
key is pressed, the screen will clear and show a question
mark in the top left hand corner. This is because CP
1M
does not understand
I
CTRL
I -
[!J , as a command. After printing a blank line the system prompt
is printed again, with the cursor to the right of it.
Now obtain a directory of the utility ROM by typing "DIR C:" if the ROM
is in ROM socket 2, or "DIR B:" if it is in ROM socket 1. For the purposes
of this illustration it will be assumed that it is in ROM socket 2 as supplied.
The display will show:
?
A>dir c::
C: PIP COM STAT
C: FILINK COM TERM
A>_
COM SUBMIT ~OM XSUB
COM CONFI6 COM
COM
Because only two lines and a new system prompt have been written on the screen,
the screen has not needed to scroll. However if the command is typed again,
the "?" will scroll off the top of the real screen, and show the following:
A>dir c::
C: PIP
COM
STAT
COM
:
SUBMIT COM
XSUB
COM
C: FlUNK
COM TERM
COM
:
CONFI6
COM
A>dir
c::
C: PIP
COM
STAT
COM
:
SUBMIT
COM
C: FlUNK
COM
XSUB
COM
TERM
COM
:
CONFI6 COM
A>I
2-52
The "?" is still the first character on the virtual screen. This can be seen in
one of two ways. Pressing the
I
CTRL
I
and
[!]
cursor key will display the first
lines of the virtual screen because these keys move the real screen backwards
one page (i.e. one real screen) on the virtual screen. Pressing the space bar (or
any other key) will return to the original display. Alternatively the screen can
be scrolled up by pressing the
I
SHIFT
I
and
[±]
cursor key. Again pressing
the space bar or another key will return the real screen to show the cursor.
To show the effect of this sequence of operations in non-tracking mode, first
clear the screen again using
I
CTRL
I -
[!J or the
I
CLR
I
key. Then press the
I
SCRN
I
key
(I
SHIFT
I +
~).
Nothing will appear to happen. Now obtain
two directories of the utility ROM in drive C: by typing "DIR C:" as before.
The screen will show:
?
A>dir
c::
c:
PIP COM STAT COM SUBMIT
COM ,
XSUB COM
C: FlUNK COM
TERM COM CONFI6 COM
A>dir
c::
C: PIP COM STAT COM SUBMIT COM XSUB COM
C: FlUNK COM TERM COM CONFI6 COM
Note how the "?" on the first line remains visible in contrast to the same se-
quence of operations in the tracking mode. This time the cursor and CP
1M
system prompt has disappeared off the real screen. They are further down the
virtual screen just outside the window. They can be seen by pressing the
I
SHIFT
I
+
[±]
cursor key to move the screen up. This leaves the real screen window
locked on these particular eight lines, so that typing "DIR C:" again will write
the directory outside the real screen. Pressing the
I
SCRN
I
key again will cause
the tracking mode to be restored and the screen will move up to show the cur-
sor. When returning to tracking mode the cursor is positioned in the centre of
the screen and so the screen will appear as follows:
A>dir
c::
C: PIP COM STAT
C: FILINK COM TERM
A> •
COM SUBMIT COM XSUB
COM CONFI6 COM
2-53
COM