Campbell Scientific CR7 Measurement and Control System - Manual (Page 32)

SECTION 1. FUNCTIONAL MODES
1-4
When the *0, *B, or *D Mode is used to compile,
all output ports and flags are set low, the timer
(Instruction 26) is reset, and data in Input and
Intermediate Storage are RESET TO ZERO.
The CR7 should normally be left in the *0 Mode
when logging data. This Mode requires slightly
less power than Modes which frequently update
the display.
1.5 MEMORY ALLOCATION - *A
1.5.1 INTERNAL MEMORY
There are eight sockets on the CR7 CPU board
which are used for Read Only Memory (ROM)
or Random Access Memory (RAM). The basic
CR7 is provided with 64K of memory: three 8K
Programmable Read Only Memory (PROM)
chips for a total of 24K ROM and five 8K RAM
chips. Appendix E describes how to change
RAM and ROM chips.
When powered up, the CR7 displays HELLO
while performing a memory check. As the
check is performed, a number on the right of
the display is incremented as each 8 K block of
memory is checked. With standard memory the
count will stop at 8. If additional memory
card(s) are present, the count will proceed
accordingly. The Power-up memory check is
quite extensive and can take considerable time
if the 709 512K Memory Card is installed. To
abort the extensive test (a shorter version is still
performed), press the # key. When the memory
test is completed, the number of K bytes of
RAM plus ROM is displayed.
The size of RAM, including any additional
memory cards which may be present, can be
determined with the *A Mode (Section 2.4.2)
There are 1744 bytes allotted to program
memory. This memory may be used for one
program table or shared among all program
tables. Tables 3.9-1 to 3.9-4 list the amount of
memory used by each program instruction.
Input Storage is used to store the results of
Input/Output and Processing Instructions. The
values stored in input locations may be
displayed using the *6 Mode (Section 1.3).
Intermediate Storage is used by Output
Processing Instructions to store the results of
intermediate calculations necessary for
averages, standard deviations, histograms, etc.
Final Storage holds output data, the results of
Output Processing Instructions which are stored
when the Output Flag is set high (Section 3.7).
The data in Final Storage can be displayed
using the *7 Mode (Section 2.3).
Figure OV2-1 illustrates the use of Input,
Intermediate, and Final Storage.
Each Input or Intermediate Storage location
requires four bytes of memory. Each Final
Storage location requires 2 bytes of memory.
Low resolution data points require 1 Final
Storage location and high resolution data points
require 2. Section 2 describes Final Storage
and data retrieval in detail.
Table 1.5-1 lists the basic memory areas and
the amount of memory allotted to them in the
standard CR7.
TABLE 1.5-1. Memory Allocation in Standard CR7
Program System Input Intermediate Final Storage*
PROM Memory Memory Storage* Storage* Storage* Standard w/709
Memory Card
Avail. bytes 24K 1744 2160 128 256 36,672 590,960
Avail. Loc. - - - 32 64 18,336 280,480
*Default allocation on power-up