Tektronix 4010 Maintenance Manual page 114

Circuit Description-4010 Maintenance
TSTROBE
CSTROBE
TBUSY
6-2
Strobes data into the Terminal to
be displayed on the screen, etc. 1.6
microsecond pulse synchronized to
the 614 kHz clock.
Strobes data to the computer. Pulse
width 1.6 microseconds sync'd to
the clock. Must not occur more
than 2 microseconds after CPUNT
goes low. TSTROBE may be
asserted simultaneously (from the
same source) to provide local copy
to the Terminal.
Terminal is busy writing a character
or vector, etc. TBUSY controls the
tim ing of data transm itted to the
Terminal. Upon receipt of a byte of
data, the Terminal will assert
TBUSY by the trailing edge of
TSTROBE if the byte is to make
the Terminal busy. No condition,
with the exception of MARG, shall
assert TBUSY except momentarily.
(MARG can be patched out of
TBUSY.) The Terminal will, how-
ever, accept data if TBUSY is high
or low although the results in that
case are not defined. TBUSY does
not inhibit transmission of data
from the Keyboard to the com-
puter.
Computer (Interface) is busy
accepting a character. Controls the
tim ing of coordi nate data trans-
mitted to the computer. A low on
CBUSY will not inhibit the Key-
board, allowing Keyboard inter-
rupts when CPUNT is not asserted.
Interfaces which must lock out the
Keyboard should do so with
KLOCK.
Suppresses Terminal response to
TSTROBE. TSUP should be used
by auxiliary devices which need to
blank the Terminal to incoming
data, such as a paper tape punch
when punching binary data. BTSUP
should be asserted in response to
CPUNT by devices (such as buffers
used in error correction schemes)
intended to intercept data on
behalf of the Terminal. In such
cases the assertion of BTSUP
should be delayed 2 clock periods
to avoid interference with copy of
locally generated data.
LCE
KLOCK
TAPE FETCH
MARG
TOPEN
Blanks the entire Terminal (in-
cluding aux devices to data). A
typical use is in a multi-drop system
to suppress messages to other ter-
minals. If the Keyboard is to be
active while the Terminal is blanked
to incoming data, BTSUP should be
asserted only in response to
CPU NT, delayed two clock cycles
from the beginning of CPUNT.
Indicates last character sent to Ter-
minal was the ESC (Escape) control
character.
Inhibits the Interface from
accepting CSTROBE. This signal is
used by devices such as line buffers
wh ich need to intercept data
destined for the computer.
Inhibits Keyboard. Normally held
at a high level.
A pulse or level provided by (typi-
cally) some small computer inter-
face to cause a paper tape reader or
analagous device to read data.
Z axis information.
Counting pulses for X and
Y Registers.
Indicates that the Terminal is at
Margin 1. With a directly connected
Interface th is corresponds to Page
Full. High active.
I ndicates that the X Register is
counting past the right margin (end
of line). Used by the Automatic
Carriage Return/Line Feed logic.
When in the Alpha Mode, EOL
going active causes an Automatic
Carriage Return (CR )/line Feed
(LF) function.
Disables Top-of-Page circuit
allowing an increased number of
lines. Not brought out to minibus
except by straps. Activation of
TOPEN depends upon user require-
ments.
REV. C, APR. 1976