Campbell Scientific COM300 Voice Communication Modem - Manual (Page 19)

C-1
Appendix C. Changing RAM or PROM
Chips in the CR10
The CR10 has two sockets for Random Access Memory (RAM) and one socket for
Programmable Read Only Memory (PROM). The standard CR10 has 64K of RAM, (a 32K
RAM chip in each socket). Earlier CR10s had 16K of RAM (an 8K RAM chip in each
socket).
C.1 Disassembling the CR10
The sockets provided for RAM and PROM are located on the CR10 CPU
circuit card inside the CR10 can. To expose the RAM and PROM sockets,
remove the two Phillips head screws from the end opposite the connectors.
Remove the end cap. The ends of two circuit cards and the RF shield will be
visible (see Figure C-1). Now lay the CR10 on a flat surface, (i.e., a table), and
push on the RF shield with your thumbs while grasping the can with your
hands. Remove the circuit cards from the can. Orient the cards with the
connector on the left and with the card that matches Figure C-2 component-side
up. The Central Processing Unit (CPU) is found at location H-9 and the three
slots for RAM and PROM will be directly beneath it.
C.2 Installing New RAM Chips in CR10 with 16K RAM
The two 8K RAM chips are found at locations C11 and C14. With a small flat
screw driver gently pry out the two 8K RAM chips at these locations and
replace them with the 32K RAM chips provided in the memory upgrade. The
new chips should be installed so the notched end is towards the nearest card
edge. Before pushing the chips into the socket make certain that all the pins are
correctly seated. After installing the 32K chips, check for pins that may be bent
or not firmly seated in the socket. If you notice a bent pin, remove the chip,
carefully straighten it and repeat the installation procedure.
C.2.1 Changing Jumpers
There are six jumpers used to configure hardware for different RAM sizes.
Figure C-2 shows the location of the jumpers and a magnified view of the
jumper settings for different memory configurations. A pin or small screw
driver tip will work best for pulling these jumpers and relocating them.
C.2.2 RAM Test
Attach the CR10KD Keyboard/Display and apply power to the CR10. After
the CR10 executes the RAM/PROM self test, the number 96 should be
displayed in the window. The number is the sum of Kbytes in RAM (64) plus
the number of Kbytes in ROM (32).