Operator`s manual

SECTION 1. FUNCTIONAL MODES
1-4
compilation. The display is not updated after
entering *0.
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 values
contained in Input and Intermediate Storage are
RESET TO ZERO.
The 21X 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 8 sockets on the 21X CPU board
which are used for Read Only Memory (ROM) or
Random Access Memory (RAM). The basic
21X 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 21X displays HELLO
while performing a self check; the result of the
check is then displayed. The 8 characters in the
display represent the 8 memory sockets
numbered from left to right: 1 means a good
chip is in the corresponding socket; 0 means the
socket is empty or an error was detected in the
chip. For example, when equipped with
standard memory, the display will read
"11:111111"; the five 1s on the left represent the
8K RAM chips; the three 1s on the right, the
three 8K PROMs.
There are 978 bytes allotted to program
memory. This memory may be used for 1
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 4 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 21X.
TABLE 1.5-1. Memory Allocation in Standard 21X
(24K ROM, 40K RAM)
Program System Input Intermediate Final
PROM Memory Memory Storage* Storage* Storage*]
Avail. bytes 24K 978 1022 112 256 38,592
Avail. Loc. --- --- --- 28 64 19,296
*Default allocation on power-up