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2-8 Theory of Operation
NovaJet 500/630/700 Series Service Manual
The gate array contains the hardware logic for jet firing, monitoring
changes in the Carriage Assembly position, controlling DMA through
the parallel port, and generating the PWM (Pulse Width Modulation)
waveforms for the servo controller.
The gate array is a Xilinx device. It is a static RAM-based field pro-
grammable gate array. This means that the logic that it implements is
determined by configuration information in an internal RAM storage
area. Each time power is turned on, this information must be down-
loaded from the system EEROM. This type of gate array allows for the
flexibility of upgrading the logic by simply downloading the new system
software.
Memory Circuits
Memory is used to retain large amounts of information. This informa-
tion is stored in the device memory in the form of binary bits.
Printer memory consists of Flash EEPROM, DRAM, and EEPROM.
Maximum installable memory is as follows:
DRAM = 128 MB
Flash EEPROM = 1 MB
Serial EEPROM = 1KB
Flash EEPROM
Flash EEPROM is Electrically Erasable, Programmable, Read Only
Memory used to store instructions and data constants which the
microprocessor can access and interpret, with no loss of information
when power is off.