SAB80C515A-5 Datasheet, PDF (9/108 Pages) Siemens Semiconductor Group – 8-Bit CMOS Single-Chip Microcontroller Family

Memory Organization
3.1 Program Memory, ROM Protection
The SAB 83C515A-5 has 32 Kbyte of on-chip ROM, while the SAB 80C515A has no internal
ROM. The program memory can externally be expanded up to 64 Kbyte. Pin EA determines
whether program fetches below address 8000H are done from internal or external memory.
As a new feature the SAB 83C515A-5 offers the possibility of protecting the internal ROM against
unauthorized access. This protection is implemented in the ROM-Mask. Therefore, the decision
ROM-Protection ’yes’ or ’no’ has to be made when delivering the ROM-Code. Once enabled, there
is no way of disabling the ROM-Protection.
Effect: The access to internal ROM done by an externally fetched MOVC instruction is disabled.
Nevertheless, an access from internal ROM to external ROM is possible.
To verify the read protected ROM-Code a special ROM-Verify-Mode is implemented. This mode
also can be used to verify unprotected internal ROM.
ROM-Protection
no
yes
ROM-Verification Mode
(see ’AC Characteristics’)
ROM-Verification Mode 1
(standard 8051 Verification Mode)
ROM-Verification Mode 2
ROM-Verification Mode 2
Restrictions
–
– standard 8051
Verification Mode is
disabled
– externally applied MOVC
accessing internal ROM is
disabled
Semiconductor Group
3-2