
MC68F375
MASK ROM MODULE
MOTOROLA
REFERENCE MANUAL
Rev. 25 June 03
12-7
12.5 Bootstrap Information Words (ROMBS0–ROMBS3)
Typically, reset vectors for the system CPU are contained in non-volatile memory and
are only fetched when the CPU comes out of reset. The bootstrap information for the
processor controlling the system are contained in the ROM module in the four words
ROMBS0–ROMBS3. ROMBS0 responds to address 0x000000, ROMBS1 responds to
0x000002, ROMBS2 to 0x000004 and ROMBS3 to 0x000006 on the IMB3. The boot-
strap information is specified by the user along with the contents of the array and is
programmed along with the contents of the array, on the same mask layer. These reg-
isters are read only from the IMB3 in normal mode or bootstrap mode. IMB3 writes do
not affect the contents of these registers. In bootstrap mode, ROMBS0–ROMBS3 only
respond to supervisor program space accesses. In normal mode, they only respond to
supervisor data space accesses.
Table 12-5 SIGLO Bit Settings
Bit(s)
Name
Description
15:0
RSP[15:0]
ROM signature pattern. These 16 bits, when concatenated with the 3 bits contained in SIGHI,
form a 19-bit unique signature used to verify the contents of the ROM array. This information is
programmed along with the contents of the array, on the same mask layer.
ROMBS0 — ROM Bootstrap Word 0
0xYF F830
MSB
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
LSB
16
SP[31:16]
RESET:
U1
NOTES:
1. The default state of these bits is defined by customer-specified options.
U1
ROMBS1 — ROM Bootstrap Word 1
0xYF F832
MSB
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
LSB
0
SP[15:0]
RESET:
U1
NOTES:
1. The default state of these bits is defined by customer-specified options.
U1
ROMBS2 — ROM Bootstrap Word 2
0xYF F834
MSB
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
LSB
16
PC[31:16]
RESET:
U1
NOTES:
1. The default state of these bits is defined by customer-specified options.
U1
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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