Table of Contents
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SECTION
1.
FUNCTIONAL MODES
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
(lnstruction
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
2'lX
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;
O
means
the
socket is empty or
an error was detected
in
the
chip.
For
example, when equipped with
standard memory, the display
will
read
"1
1:1
1
1
1 1
1";
the
five
1s
on
the left represent the
8K RAM
chips;the three
1s
on
the right, the
three
8K
PROMS.
PROM
Avail.
bytes
24K
Avail.
Loc.
"Default allocation on
Program
Memory
978
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
'
lnpuUOutput
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
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
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.
Input
Intermediate
Final
Storage* Storage*
Storage
112
256
38.592
64
19.296
TABLE 1.5-1. Memory Allocation in Standard
21X
(24K
ROM,40K
RAM)
System
Memory
1022
1-4
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