Tandy 1400LT Service Manual page 17

Floppy Disk Controller
Power Supply
No. of Connectable Disks
Data Transmission
Transfer Rate
BOOT Select Switch
RS-232C INTERFACE
Standard
Device
Word Length
Parity
Stop Bit Length
Baud Rate
Output Signal Level
Input Signal Voltage
PRINTER INTERFACE
Control
output
RTC (REAL TIME CLOCK)
Device
X'TAL Oscillation
Battery Back Up
Accuracy
POWER SOURCE
Main Battery
Back up Battery
Battery Voltage Warning
~ P D 7 2 0 6 5 C CMOS type of 765.
Power supply is controlled by software.
Controller can control up to 3 FDD. However, to connect the
external FDD, an extra power supply is required.
DMA transmit
250Kbit/sec
Drive assignment depends on the position of the BOOT Select
Switch as follows.
3.5 inch boot
5 inch boot
DRIVE 1 DRIVE A DRIVE C
DRIVE 2 DRIVE B DRIVE B
EXT FDD DRIVE C DRIVE A
Conform to EIA Standard
TC8570P
DS14C88 and DS14C89AN
5,6,7,or 8 bits
Even, Odd, or None
1, 1.5 or 2 bits
50,75,110,150,300,600,1200,2400,4800,or 9600BPS
Output signal based on i- 12V and -12V
SPACE
=
+3V
-
+15V
MARK = -3V
-
-15V
The printer is controlled by the STROBE and BUSY signals.
When the printer is not busy, the CPU receives an interrupt
signal, IRQ7.
Normal commercial printers can be used, if they have TTL input.
When a printer is used, the connector can be plugged in or
removed without destroying the inner circuits of the devices
regardless of power ON/OFF. In addition, the interface circuits
can effectively withstand static charge breakdown.
R I C H 0 RP5C 15
32.768kHz
Time counting function is maintained by the battery even when
the system is turned OFF.
f 5 minutedmonth
12V, 2200mAh
,
Nickel-Cadmium .battery
A Nickel-Cadmium battery of 3.6V 50mA is used to hold the
Time Data of RTC
The first warning is indicated by Low Battery RED LED and
beep 2 times.
The user is instructed to charge the battery voltage to 1 1.7V
-
1 1.9V.
After the first warning, the system can be used for about 30
minuites with the FDD 10% duty.
The second warning is indicated by Low Battery RED LED
flashing and beep 5 times.
The user is instructed to shut down the system at a battery
voltage of 1O.W
-
11.4V. User should close current task tile. If
used after Low Battery warning, the system shuts down and loses
all RAM data.
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