CS8900A
Crystal LAN™ ISA Ethernet Controller
4.3.9 Boot PROM Base Address
(Read/Write, Address: PacketPage base + 0030h)
Address 0033h
Address 0032h
Address 0031h
Address 0030h
The most significant nibble of
Boot PROM base address. Contains portion of Boot PROM
The least significant byte of
the Boot PROM base
address.
Reserved
The high-order nibble is
reserved.
base address.
The lower three bytes (0030h, 0031h, and 0032h) of the Boot PROM Base Address register are used for the 20-bit
Boot PROM base address. The upper three nibbles are reserved. See Section 3.6 on page 25.
After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM
is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 19.
Reset value is: XXXX XXXX XXXX 0000 0000 0000 0000 0000
4.3.10 Boot PROM Address Mask
(Read/Write, Address: PacketPage base + 0034h)
Address 0037h
Address 0036h
The most significant nibble of
Boot PROM mask address.
The high-order nibble is
reserved.
Address 0035h
Address 0034h
The least significant byte of
the Boot PROM mask
address. Must be written as
00h.
Contains portion of Boot PROM
mask address. The lower-order
nibble must be written as 0h.
Reserved
The Boot PROM address mask register indicates the size of the attached Boot PROM and is limited to 4K bit incre-
ments. The lower 12 bits of the Address Mask are ignored, and should be 000h. The next lowest-order bits describe
the size of the PROM. The upper three nibbles are reserved.
For example:
Size of Boot PROM
4k bits
Register value
XXXX XXXX XXXX 1111 1111 0000 0000 0000
XXXX XXXX XXXX 1111 1110 0000 0000 0000
XXXX XXXX XXXX 1111 1100 0000 0000 0000
8k bits
16k bits
See Section 3.6 on page 25.
After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM
is found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 19.
Reset value is: XXXX XXXX XXXX 0000 0000 0000 0000 0000
CIRRUS LOGIC PRODUCT DATA SHEET
DS271PP3
45
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