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4.6.2.2 Timing Signals
For normal character printing, five consecutive STROBE inputs
to LSI chip ME16, generate timing outputs
~-~
as shown in Figure
4-6. These timing intervals correspond to the five full-step columns
in the character matrix. The quiescent state of this strobe counter is
DCWO (internal to the chip) which corresponds to the space interval be-
tween characters. During DCWO, the STROBE input generates a CLKTB2
pulse which clocks the next character to the output of the shift register.
The DCW1-DCW5 timing outputs are used to address the appropriate column
in the Ifu11-step" ROM (character generator).
If a 9 x 7 character matrix is used, during each video interval
both a STROBE pulse and a DLYSTB pulse of the same width is generated as
shown in Figure 4-6. During normal character printing, four consecutive
DLYSTB inputs to LSI chip ME16, generate timing outputs DCW01-DCW04. These
four timing intervals correspond to the four additional ("half-step")
columns in a
9
x
7
matrix. Timing signals (DCW01-DCW04) are used to
address the appropriate column in the Iha1f-step" ROM (character generator).
Du·ring elongated character printing, the UCC latch (internal to
LSI chip ME16) allows alternate STROBE pulses to clock the internal
strobe counter and alternate DLYSTB pulses to clock the delayed strobe
counter. As a result, timing outputs DCWf-DCW5 and DCW01-DCW04 are
twice as long during elongated character mode than during normal character
mode.
During the space interval between character (DCWO), timing signals
DCWl-5 and DCW01-04 are all reset.
4.6.3 CHARACTER GENERATOR (ROM)
The logic board can contain up to four ROM elements, depending
on the selected character generating capabilities of that printer.
(1) 5 x 7, 64-Character Set - ME2 only or ME4 only.
(2) 9 x 7, 64-Character Set - ME2 and MEa only, or ME4 and ME10
only.
4-18
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