Umtech VIDEOBRAIN Expander 2 User guide

V id e o B r a in
Home Computer
Accessory
Owner’s
Handbook
A ccessory: Expander 2
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V id e o B r a in
EXPANDER 2
OWNER’S HANDBOOK
Accessory
• Acoustic coupler
VideoBrain Com puter Company
2950 Patrick Henry Drive
Santa Clara, California 95050
All rights reserved including the right of
reproduction in whole or in part in any form.
P/N 40-0033 Rev. 0 8/78
Printed in the United States of America
1

Expander 2 Introduction
Expander 2 data modems are designed fo r acoustic
operation via the switched telephone network or private
line installation. Acoustically coupled with most
telephone sets, the Expander 2 offers a reliable and
convenient method of data transmission.
Expander 2 is an originate-only modem for up to
300 baud operation.
^daaN .
answer
J s ' COMPUTER . / I
EXPANDER 2 s ' s '
h v . VIDEOBRAIN
FIG. 1
2

Controls and Indicators
Following are the controls and indicators found on
the coupler.
Front Panel
1. Full/Half: this switch sets the duplex (communication)
mode of the Expander 2 unit. For half duplex operation
(local copy back), push the switch in. Full duplex
(no copy back) is when the switch is out.
Note: before operating in half duplex mode, make sure
that the system or the terminal does not provide a
local copy back. If so, leave switch in full duplex.
2. PWR: this indicator shows that AC power is applied to
Expander 2.
3. CTS: this indicator shows that a valid carrier signal is
being received from the opposite receiving modem.
Rear Panel
1. On/Off: this switch applies AC power to Expander 2.
2. 115 VAC 60 Hz Only: this grounded 3-wire cord plugs
into any 3-wire 115 VAC 60 Hz receptacle.
3. EIA RS232-C: the 25-pin connector is the standard EIA
RS232-C interface. Plug cable from the Expander 1
right into this connector.
3

Installation
AC Power Connection
Expander 2 is provided with a 3-wire power cord which
can be connected to any 115 VAC 60 Hz grounded wall
outlet. Apply power through this cable.
EIA Connection
Plug the supplied EIA cable into the 25-pin EIA
connector in the back of Expander 1 as shown below.
Pin connections and levels conform to the EIA
RS232-C specifications. See the interface chart for
Expander 2.
Plug the other end of the EIA cable into the rear panel
of VideoBrain’s Expander 1 (Input/Output interface).
The modem plug is appropriately labeled on the back
panel of Expander 1, as shown in its Owner’s
Handbook.
EIA
CONNECTOR EIA
CABLE
POWER CORD
FIG 2.
4

Expander 2 Location
For operation, locate a place for Expander 2 close
enough to the telephone so the handset cord can easily
reach Expander 2. Avoid places such as on top of a
terminal, TV set, air conditioner, etc. Some of this
equipment can generate electrical or magnetic fields
which may cause transmission errors.
Operating Procedures
The follow ing is a detailed sequence on how to operate
Expander 2 in a typical tim esharing environment. Insert
Timeshare (CM01) cartridge in the VideoBrain.
Placing a call
1. Turn the AC power switch on. Check that the PWR
indicator illuminates.
2. Choose the proper setting for the Full/Half duplex
switch.
3. Dial the number of the desired computer or remote
station.
4. Listen until the high-pitched carrier tone is heard from
the com puter or the remote station.
5. Place telephone handset in acoustic coupler, with cord
to the rear.
6. Check to ensure that the CTS indicator lights up after
one or two seconds. When this indicator is on, the
exchange of data can begin.
5

Disconnecting a call
When exchanging data with a computer system, simply
sign o ff from the system and the com puter will
disconnect your call.
At any time a disconnect can be accom plished by any
of the two parties by removing the handset and putting
it back in the cradle on the telephone, thereby
disconnecting the line.
Specifications
Data Rate: 300 baud
Modulation: Phase coherent FSK
Operation: Asynchronous, serial by bit
Telephone
Interface: Acoustical via the WE 500 handset
or equivalent
Audio Data
Frequencies: Receive Transmit
Mark 2225 Hz 1270 Hz
Space 2025 Hz 1070 Hz
Tolerance: ±6 Hz ±2 Hz
Receive
Performance: Less than 5% jitte r and 10% bias
distortion operating at 300 baud
6

Receive
Sensitivity: Acoustic mode -4 8 dBm ±3 dB,
max hysteresis is 4 dB
Transmit
Level: Pot a dju sta b le- 1 5 t o -21 dBm
Timings: Carrier detect —
on 500 ms ±200 ms
off 50 ms ±30 ms
Clear to send —
on 700 ms ±300 ms
off 2 ms
Power
Requirements: 115 VAC ±10%, 60 Hz, 5 W
Environmental: Operating temperature 0°C to 60°C
Storage temperature -20 °C to 70°C
Relative hum idity 8% to 95% relative
Dimensions: 3%" high
7V2" wide
IOV2" long
N,
Indicators: CTS — Received carrier/clear to send
PWR — Power on
Controls: ON/OFF — Power on/off
FULL/HALF — Duplex
Interfaces: EIA RS232-C
7

Interfaces
Desig. EIA RS232-C Pin Number
AA Protective Ground 1
BA Transmit Data 2
BB Receive Data 3
CB Clear to Send 5
CC Data Set Ready 6
AB Signal Ground 7
CF Received Line Detector 8
+ P Positive Voltage 9 (test only)
- P Negative Voltage 10 (test only)
CD Data Terminal Ready 20 (optional)
8