Atmel C51 Table 2. J9 Switches, Table 3. J16 Switches, Socket and Quartz Crystal

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 thr ee
sockets.
Crystal may be easily changed on each socket.
10
MAP SELECT EA
Bit
Number Bit Mnemonic Description
1MAP
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
0EA
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
0ISP2
In System Programming 2 (external Flash memory)
RESERVED
MUST BE OFF (set to 1)
J11
PSEN
ALE
ISP1
User Code
10
10
J11
J9
J16
J9
J16
EA
MAP SELECT
ISP2
RS232 Cable to PC
0
7
Set = 1
Clear = 0
OFF