Tektronix 4010 Maintenance Manual page 10

Installation and Operation-4010 Maintenance
• ox,
780Y
512X, 390Y
(Center)
1023X, 780Y •
Y
axis
•
• OX,OY
1023X, OY •
X axis
..
Fig. 1-6. Basic address positions on the display screen.
Interactive - Graphic Input (Gin) Mode causes the
Terminal to automatically send its status and/or the
address of the display beam to the computer in response
to commands from the computer. A crosshair cursor
may be displayed in Gin Mode as a preparatory status.
Local operation occurs when the keyboard LOCAL!
LINE switch is placed in the LOCAL position. The
Terminal is then isolated from the computer and keyboard
entries are displayed or otherwise executed by the Ter-
minal.
4010-1 Terminals have a Hard Copy Mode which permits
a hard copy reproduction of the display to be made if a
Hard Copy Unit is connected to the Terminal. The mode
can be initiated by computer command, by a MAKE COPY
key on the Terminal keyboard, or by a switch on the Hard
Copy Unit.
Transmitting
If the keyboard switch is at LI N E position, data entered
at the keyboard is transm itted in ASC II-coded form to the
computer. The keyboard generates an eighth bit which is
always either high or low, depending upon a strap option in
the keyboard. This may be sent as set at the keyboard, or
may be determined by the interface unit. Except for closing
brace (AL T MODE) or DEL (RUBOUTl, the keyboard is
not capable of sending data from the last two columns on
the right in the ASCII code chart shown in Fig. 1-7.
Receiving
General. The Terminal receiving circuits are essentially
divorced from the keyboard and transmitting circuits while
the keyboard switch is at LINE position. Data is then
'-6
received as a result of transmission from the computer,
including data being echoed by the computer or modem.
However, data entered at the keyboard is applied to the
receiving circuits if an ECHO signal is being asserted by the
interface unit. ECHO is controlled by a switch or a strap
option, depending upon the type of interface. The ECHO
signal creates a situation referred to as echoplexing.
The Terminal response to signals thus received is
essentially the same in either case, and depends upon the
operating mode.
Alpha Mode. The Alpha Mode is the initial condition of
the receiving circuits. In addition, it occurs in response to
receiving a US, CR, or ESC FF. It is also initiated by
entering PAGE or RESET at the keyboard. A pulsating
cursor indicates the writing position of the next character.
Alphanumeric characters are written on the display screen;
control characters are executed by the Terminal. Lower
case characters are written as upper case; Grave Accent
(opening single quotation mark) is written as Commercial
At; and Opening Brace is written as an Opening Bracket.
Space causes spacing only. The 4010 does not respond to
Vertical Line, Closing Brace, or Overline (Tilde). Rubout
(DEL) is accepted and sent as a character, but does not
cause a space or print. Control characters and control char-
acter sequences cause effects as listed in Table 2-1. Op-
tional accessories may respond to other commands or se-
quences as determined by the optional accessory. Refer to
Table 2-2 for a listing of Alpha Mode specifications.
Graph Mode_ Control character GS puts the Terminal in
Graph Mode. Then the Terminal draws vectors (either
written or unwritten) in response to graphic address inputs
as explained in Tables 2-4 and 2-5. The Terminal can still
respond to control characters and control character se-
quences as explained in Table 2-1. Graph Mode ends and
Alpha Mode occurs upon receipt of control characters US,
CR, or control character sequence ESC FF. Graph Mode
also ends upon receipt of ESC SUB, which sets Gin Mode
and displays the crosshair cursor. Graph Mode can also be
ended by pressing PAGE or RESET at the keyboard. Refer
to Table 2-3 for Graph Mode specifications.
Interactive
Gin Mode. Gin Mode occurs in response to receipt of
ESC ENQ at any time the Terminal is "on line". It also
occurs in response to an ESC SUB which turns on the
crosshair cursor. ESC SUB should not be entered at the
keyboard while "on line" because immediate and erroneous
transmission may occur. Receipt of ESC ENQ while in
Alpha Mode results in immediate transmission of the
Terminal status and the address of the point at the lower
left corner of the Alpha cursor. CR or CR and EOT will
automatically be transmitted immediately after the address,
if selected by a strap option on TC-2. (EOT can not be sent
®I