Campbell CR9000, Инструкция по эксплуатации

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Section 2. Data Storage and Retrieval
2-2
When the CR9000 compiles and runs a program that uses flash memory, it
checks to see if the program is different from the last program it ran. If the
program has changed (including any changes to comments), flash memory is
erased and reset. If the program is the same, the CR9000 leaves the flash
memory as it was, appending data to tables that are not yet full.
The 1.5 M bytes of flash memory available for data storage is in six 256 K
erasable segments. A segment can only store data from 1 table (otherwise the
tables could not be individually reset). This is the reason a maximum of six
tables are possible (none larger than 256 K). Automatic allocation (negative
number for FlashOut size) will divide tables on the 256 K boundaries.
2.1.3 9080 PAM Module – PCMCIA PC Card
The CR9000 9080 PAM Module allows expanding the CR9000’s storage
capacity with Type I, II, or III PCMCIA Cards. SRAM, ATA Flash, and ATA
hard disk cards are supported. ATA hard disks cards cannot withstand the
environmental temperature range of the CR9000’s specifications. A program
can send a maximum of 30 data tables to PC cards.
Data stored on cards can be retrieved through one of the communication links
to the CR9000 or by removing the card and inserting it in a PC card slot in a
computer. Converting the data using the computer's PC card slot is much
faster than retrieving it through the CR9000 using one of the communication
links.
The CR9000 uses an MS DOS format for the PC cards. Cards can be
formatted in a PC or in the CR9000.
TABLE 2.2-1. CR9000 DATA TYPES
Data Type Size Range Resolution
LONG 4 bytes -2,147,483,648 to +2,147,483,647 1 bit (1)
IEEE4 4 bytes 1.8 E –38 to 1.7 E 38 24 bits (about 7 digits)
FP2 2 bytes -7999 to +7999 13 bits (about 4 digits)
2.2 Internal Data Format
Data are stored internally in a binary format. Variables and calculations are
performed internally in IEEE 4 byte floating point with some operations
calculated in double precision. There are two data types used to store data:
IEEE4 four byte floating point and Campbell Scientific two byte floating
point (FP2). The data format is selected in the instruction that outputs the
data. A third data type, the four byte integer format (LONG) is used by the
CR9000 for storing time and record number. Within the CR9000, time is
stored as integer seconds and nanoseconds into the second since midnight,
the start of 1990. While IEEE 4 byte floating point is used for variables
and internal calculations, FP2 is adequate for most stored data. Campbell
Scientific 2 byte floating point provides 3 or 4 significant digits of
resolution, and requires half the memory space as IEEE 4 byte floating
point (2 bytes per value vs 4).