
Technical Data
MC68HC705C8A 
—
 Rev. 3
112
EPROM/OTPROM (PROM)
MOTOROLA
EPROM/OTPROM (PROM)
9.4.2  Verify PROM Contents
The verify PROM contents routine is normally run automatically after the 
PROM is programmed. Direct entry to this routine causes the PROM 
contents of the MCU to be compared to the contents of the external 
memory locations of the EPROM at the same addresses. 
To invoke the verify PROM contents routine of the MCU, take these 
steps: 
1.
Set switch 1 in the ON position (restores V
DD
). 
Connect V
PP
 to V
DD
. 
Set switches S3, S4, and S6 in the OFF position. 
2.
3.
4.
Set S5 in the ON position. 
5.
Set switch 2 in the OUT position (routine is activated). 
The red LED is not illuminated during this routine, since no 
programming takes place. If verification fails, the routine halts with 
the failing address in the external memory bus. When the green 
LED is illuminated, verification is completed successfully and the 
routine is finished. 
6.
Set switch 2 in the RESET position. 
At this point, if another routine is to be performed on the MCU being 
programmed, the user can set switches S3, S4, S5, and S6 to the 
positions necessary to select the next routine and move switch S2 to the 
OUT position to start the routine. If no other routine is to be performed, 
remove V
DD
 from the board and remove the MCU from the programming 
socket. 
9.4.3  Secure PROM
The secure PROM routines are used after the PROM is successfully 
programmed and verified. Only the SEC bit of the option register 
($1FDF) is programmed, but V
PP
 is necessary. Once this bit is 
programmed, PROM is secure and can be neither verified nor dumped.