Instruction manual

Hardware Overview
18 025-9416
DRAM Memory
The DRAM memory (item #3, Figure 2) physically resides in one or more single in-line memory
module (SIMM) units installed into J9, J10, and J11. The base area of DRAM memory is loaded
with the operating software for the Model 640 paging terminal. This plug-in board is also used
for non-volatile storage of the subscriber database. The EMS area of the DRAM memory is used
as a storage buffer for the ADPCM voice storage and playback functions.
Maintenance Modem
The main processor board contains a modem for remote communications and system manage-
ment. The modem is accessed through any one of the trunk interfaces. Once a unique phone
number is programmed into the terminal database, the 640 can be called from any remote PC.
Expansion Slots
A custom expansion slot (J8) is provided for installation of the optional TNPP interface card
(item #8, Figure 2). This card facilitates wide area networks involving multiple paging terminals.
The main processor board has two PC-type expansion slots, which are used for the printer port or
other options. The printer card can be installed in either slot. The printer option (Part No. 950-
9758) allows a parallel printer to be connected to the paging terminal for real-time printing of
page logging (system activity).
External Hardware Interfaces
The main board has three connections exposed through the rear of the Model 640 chassis. The
FAULT connector (item #16, Figure 3) indicates a paging terminal failure for interface to an
alarm system. The male 6-pin Wiedmueller connector has three usable output pins from an
onboard relay.
The COM PORT connector (item #17, Figure 3) provides an RS-232 interface for local PC or
dumb terminal communications. A 10-foot serial cable (Part No. 709-7211) is provided with the
Model 640 for this connection. The 9-pin port can be configured for baud rates up to 9600.
The KEYBOARD connector (item #18, Figure 3) was used in conjunction with the Model 640
Console option, which is no longer sold. The connector is identical to a PC keyboard interface.
Jumper Settings
Figure 4 shows the location of each jumper on the currently shipping V53 main processor circuit
board.