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| IT- A4000
2-10. Hardware System
2- 10-1. Digital Type
This unit does not incorporate
a 4~-bit micro
computer
such
as the current
model, but consists
of system
by
setting the system control function to DSP (Digital Signal Processor) used for voice processing. ASIC is used
for the mediation
between
DSP
and all sorts of interface, the various
type of controls
are possible with
two
chips.
The role of IC which is used in IT-A4000
is described below.
DSP (Digital Signal Processor)(1C801)
All sort of recording, play back (except for voice guidance),
ASTC(1C802)
ASIC
operates
to control DRAM
and SRAM, interface key scan
and all sorts of analog circuits.
ASIC
also controls
LCD
driver
and
IC for voice
guidance.
SRAM(IC810)
DRAM (IC811 — 820)
Ten IMDRAMs
are used. DRAM which lacks bits are used for this unit. Called ARAM
(Audio RAM), guarantees
within
1% of bit lack rate.
LCD DRIVER(IC802)
This IC is 1/2 duty and enables
the display of up to 106segment.
VOICE SYNTHESIZER (1C822, 1C823)
Identical
to the current
unit. As this unit is for USA, the voice data is newly changed
only for voice guide.
FLIP- FLOP (74HC374) ( 1C806)
=95
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