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RS485 network card
Java VM on RS-485 cards

The RS485 networking cards are used in various gaming machines playing the Jackpot game. Jackpot control computer retrieves various information from the participating gaming machines and then randomly selects one gaming machine as a winner. Up to 32 RS485 cards can be connected together on one network. The network is multi-drop type with 9-bit communication protocol. Each network card is assigned an unique address with a possibility to address all cards on the network at the same time using the global address.

The hardware

Basic configuration of the card consists of:
68HC11A1 running at 7.3728MHz crystal clock
32KB of battery backed-up static RAM (expandable to 64KB)
Half-duplex RS485 driver
Several digital input/output lines providing means for gathering information from the gaming machine.
Relay for selecting the sound source

The trials

The field trials are being held at four different casino locations in the Slovak Republic. Trials have started at the end of June 1998 and are running since then. Initially, trials started in one casino with about 15 gaming. Since August 1998, trials have been extended into another three casinos. Today, there are over 60 gaming machines trialing the RS485 network cards running the Java VM for 68HC11 and executing control program written in Java.

RS485 network cards are integral part of the gaming machines. Casino gaming machines are distributed in Slovakia by NovoNMN s.r.o. Manufacturing and maintenance of the RS485 network cards is provided by SOFT-GL s.r.o.

So far, these trials are showing that it is possible to develop and maintain Java applications for the small 8-bit embedded systems running specially optimized Java Virtual Machine.

Tech info

Block diagram of RS485 network card
Detailed schematic layout (32K PDF file)
9-bit communication protocol spec.
Jackpot application source code:

Jackpot - main application class
Comms - RS485 communication thread
HostInterface - handles host control messages
Config - maintains configuration file
Timer - provides software timing functions
JackSystem - some general purpose methods Communication protocol used on RS485 cards

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