Service manual

Theory
3-5
CPU PCBA
The CPU PCBA consists of a CPU subsystem that runs the system software, updates the display,
and communicates with peripheral devices through the I/O PCBA. The CPU PCBA contains all the
major digital components and all the major analog components.
Figure 3-3: CPU block diagram
860/PCI
bridge
PCI
33 MHz
32
NVRAM
RT Clk
bus
32KX8
16
6.25 MHz
ISA
bus
ISA/PCI
dma
VGA
sdlc
2 *RS-232
irpt
eide
e-net
Xfmr
10baseT
32
33 MHz
4-32M
2-16M
DRAM
flash
256k
GDS RAM
nurse alert
MM
CODEC
st. line in
st. line out
Mono Int Spkr
MPC
860
scc1
scc2
scc3
scc4
smc1
smc2
i2c
T/S
cpu
int t/s
K/M
CTRL
keyboard
mouse
controller
1
&
2
display
cntr