Integra CROMA24 - Manual (Page 31)

Theory of Operation 31
THEORY OF OPERA
TION
Croma24 Service Manual
The gate array contains the hardware logic for dot firing, monitor-
ing changes in the Carrier Assembly position, controlling DMA for
the serial 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
programmable gate array. This means that the logic that it imple-
ments is determined by configuration information in internal RAM
storage. Each time power is turned on, this information must be
downloaded from the system ROM. 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
information 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 = 2 MB
Flash EEPROM = 1 MB
Serial EEPROM = 1 KB
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. This set of instructions
and data constants is called the “firmware” of the plotter.
The term “Flash” means that bytes cannot be individually erased.
A block or the whole device is erased at the same time and the
block or whole device is then reprogrammed. It can be erased and
reprogrammed more than 10,000 times.