Atmel C51 - Manual (Page 11)

Hardware Description
C51 Microcontrollers Demo Board User Guide 2-8
4119C–8051–3/03
Table 2. J9 Switches
Table 3. J16 Switches
Figure 2-6. Switch Configuration
Socket and Quartz Crystal The C51/C251 Demo Board provides three different sockets for microcontrollers, a
PLCC44, a PLCC68 and a DIL24.
Each socket has it own quartz crystal X1, X2 and X3.
Only one Atmel microcontroller must be plugged-in at one time, in one of the three
sockets.
Crystal may be easily changed on each socket.
1 0
MAP SELECT EA
Bit
Number
Bit
Mnemonic Description
1
MAP
SELECT
Map Select
Set to select external Flash memory zone from $10000 to $1FFFF
Clear to select external Flash memory zone from $00000 to $0FFFF
0 EA
External Address
Set to fetch internal code (on chip code).
Clear to fetch code from external Flash memory
0
ISP2
Bit
Number
Bit
Mnemonic Description
0 ISP2
In System Programming 2 (external Flash memory)
RESERVED
MUST BE OFF (set to 1)
J11
PSEN
ALE
ISP1
U
s
er
C
ode
1 0
1 0
J11
J9
J16
J9
J16
EA
MAP SELECT
ISP2
RS232 Cable to PC
0
7
Set = 1
Clear = 0
OFF