Memory

Addr.

Register

 

Bit 7

6

5

4

3

2

1

Bit 0

 

 

 

 

 

 

 

 

 

 

 

$001A

 

Reserved

R

R

R

R

R

R

R

R

 

 

 

 

 

 

 

 

 

 

 

$001B

 

Reserved

R

R

R

R

R

R

R

R

 

 

 

 

 

 

 

 

 

 

 

$001C

 

Reserved

R

R

R

R

R

R

R

R

 

 

 

 

 

 

 

 

 

 

 

$001D

 

Reserved

R

R

R

R

R

R

R

R

 

 

 

 

 

 

 

 

 

 

 

$001E

 

Reserved

R

R

R

R

R

R

R

R

 

 

 

 

 

 

 

 

 

 

 

$001F

 

Reserved

R

R

R

R

R

R

R

R

 

 

 

 

 

 

 

 

 

 

 

R= Reserved

Figure 2-2. I/O Registers (Continued)

2.3.1 ROM

The user ROM consists of 15,920 bytes of ROM located from $0180 to $3FAF and 16 bytes of user vectors located from $3FF0 to $3FFF.

The burn-in ROM is located from $3FB0 to $3FEF.

Ten of the user vectors, $3FF6–$3FFF, are dedicated to reset and interrupt vectors. The six remaining locations — $3FF0, $3FF1, $3FF2, $3FF3, $3FF4, and $3FF5 — are general-purpose user ROM locations.

2.3.2 ROM Security

Security has been incorporated into the MC68HC05RC16 to prevent external viewing of the ROM contents. This feature ensures that customer-developed software remains proprietary.1

1.No security feature is absolutely secure. However, Motorola’s strategy is to make reading or copying the ROM difficult for unauthorized users.

General Release Specification

 

MC68HC05RC16 — Rev. 3.0

 

 

 

30

Memory

MOTOROLA