com90c66 Standard Microsystems Corp., com90c66 Datasheet - Page 17

• Manufacturer Part Number: com90c66
• Description: Arcnet Controller/transceiver With At Interface And On-chip Ram Corporation
• Manufacturer: Standard Microsystems Corp.

FIGURE 7 - 16K MEMORY SEGMENT
(Memory Mapped Mode)
CHOSEN BY MS0-MS4
COUNT
255
511
FORMAT (256 OR 512 BYTE PAGE)
FIGURE 9 – RAM BUFFER PACKET CONFIGURATION
0
1
2
DATA BYTE N-1
COUNT = 256-N
SHORT PACKET
DATA BYTE N
DATA BYTE 1
DATA BYTE 2
NOT USED
NOT USED
SID
DID
A13 = 1:
8K PROM SPACE
A13 = 0:
A11 AND A12 Select one
of these 2K RAM segments.
COUNT
511
0
1
2
3
FORMAT (512 BYTE PAGE)
17
COUNT = 512-N
DATA BYTE N-1
FIGURE 8 - 16K PROM SEGMENT
LONG PACKET
DATA BYTE N
DATA BYTE 1
DATA BYTE 2
NOT USED
SID
DID
(I/O Mapped, 16K X 8 Mode)
0
CHOSEN BY MSO-MS4
SID = SOURCE ID
(DID = 0 FOR BROADCASTS)
N = DATA PACKET LENGTH
DID = DESTINATION ID
A13 = 1:
UPPER 8K PROM SPACE
A13 = O:
Lower 8K PROM SPACE