M68HC16 Z SERIES
REGISTER SUMMARY
USER’S MANUAL
D-27
D.4.2 ROM Array Base Address Registers
The reset value of the shaded bits is user specified, but the bits can be written after
reset to change the base address. If the values of ROMBAH bits ADDR[23:20] do not
match that of ADDR19, the CPU16 cannot access the ROM array.
ROMBAH and ROMBAL specify the ROM array base address. The reset state of
these registers is specified at mask time. They can only be written when STOP = 1 and
LOCK = 0. This prevents accidental remapping of the array. Because the 8-Kbyte
ROM array in the MC68HC16Z2 and the MC68HC16Z3 must be mapped to an 8-
Kbyte boundary, ROMBAL bits [12:0] always contain $0000. ROMBAH ADDR[15:8]
read zero.
D.4.3 ROM Signature Registers High
Signature registers RSIGHI and RSIGLO contain a user-specified mask-programmed
signature pattern. A user-specified signature algorithm provides the capability to verify
ROM array contents.
ROMBAH — ROM Array Base Address Register High
$YFF824
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
ADDR
23
ADDR
22
ADDR
21
ADDR
20
ADDR
19
ADDR
18
ADDR
17
ADDR
16
RESET:
1
1
1
1
1
1
1
1
ROMBAL — ROM Array Base Address Register Low
$YFF826
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
ADDR
15
ADDR
14
ADDR
13
ADDR
12
ADDR
11
ADDR
10
ADDR
9
ADDR
8
ADDR
7
ADDR
6
ADDR
5
ADDR
4
ADDR
3
ADDR
2
ADDR
1
ADDR
0
RESET:
0
0
0
RSIGHI — ROM Signature Register High
$YFF828
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
NOT USED
RSP18
RSP17
RSP16
RESET:
0
0
0
RSIGLO — ROM Signature Register Low
$YFF82A
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
RSP15
RSP14
RSP13
RSP12
RSP11
RSP10
RSP9
RSP8
RSP7
RSP6
RSP5
RSP4
RSP3
RSP2
RSP1
RSP0
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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