CS8900A_01 Datasheet, PDF (21/137 Pages) Cirrus Logic – Crystal LAN TM ISA Ethernet Controller

CS8900A
Crystal LAN™ ISA Ethernet Controller
Word Address
Value
FIRST WORD in DATA BLOCK
00h
A120h
FIRST GROUP of WORDS
01h
2020h
02h
0300h
03h
0003h
04h
0001h
SECOND GROUP of WORDS
05h
502Ch
06h
E000h
07
000Fh
08h
0000h
09h
000Dh
0Ah
C000h
0Bh
000Fh
THIRD GROUP of WORDS
0Ch
2158h
0Dh
0Eh
0Fh
CHECKSUM Value
10h
0010h
0000h
0000h
2800h
Description
Configuration Block Header.
The high byte, A1h, indicates a ‘C46 EEPROM is attached. The Link Byte,
20h, indicates the number of bytes to be used in this block of configuration
data.
Group Header for first group of words.
Three words to be loaded, beginning at 0020h in PacketPage memory.
I/O Base Address
Interrupt Number
DMA Channel Number
Group Header for second group of words.
Six words to be loaded, beginning at 002Ch in PacketPage memory.
Memory Base Address - low word
Memory Base Address - high word
Boot PROM Base Address - low word
Boot PROM Base Address - high word
Boot PROM Address Mask - low word
Boot PROM Address Mask - high word
Group Header for third group of words.
Three words to be loaded, beginning at 0158 in PacketPage memory.
Individual Address - Octet 0 and 1
Individual Address - Octet 2 and 3
Individual Address - Octet 4 and 5
The high byte, 28h, is the Checksum Value. In this example, the check-
sum includes word addresses 00h through 0Fh. The hexadecimal sum of
the bytes is D8h, resulting in a 2’s complement of 28h. The low byte, 00h,
provides a pad to the word boundary.
* FFFFh is a special code indicating that there are no more words in the EEPROM.
Table 6. EEPROM Configuration Block Example
CS8900A will not attempt to read configuration For example, a Reset Configuration Block header
data from the EEPROM.
of A104h indicates a non-sequential EEPROM pro-
3.4.3.5 Determining Number of Bytes in the Reset
Configuration Block
The low byte of the Reset Configuration Block
header is known as the link byte. The value of the
Link Byte represents the number of bytes of config-
grammed with a Reset Configuration Block con-
taining 4 bytes of configuration data. This Reset
Configuration Block occupies 6 bytes (3 words) of
EEPROM space (2 bytes for the header and 4 bytes
of configuration data).
uration data in the Reset Configuration Block. The ^{3.4.4 Groups of Configuration Data}
two bytes used for the header are excluded when _{Configuration data are arranged as groups of}
calculating the Link Byte value.
words. Each group contains one or more words of
data that are to be loaded into PacketPage registers.
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