USB97C100QFP datasheet(30/64 Pages) SMSC

30 / 64 page

SMSC DS – USB97C100

Page 30

Rev. 01/03/2001

8237 (ISADMA) REGISTER DESCRIPTION

Memory Map

Table 38 - ISADMA Memory Map

8237 MEMORY ADDRESS

DESCRIPTION

0xFC00-0xFFFF

1k Window to Packet with PNR=0x1F

0xF800-0xFBFF

1k Window to Packet with PNR=0x1E

0xF400-0xF7FF

1k Window to Packet with PNR=0x1D

0xF000-0xF3FF

1k Window to Packet with PNR=0x1C

0xEC00-0xEFFF

1k Window to Packet with PNR=0x1B

0xE800-0xEBFF

1k Window to Packet with PNR=0x1A

0xE400-0xE7FF

1k Window to Packet with PNR=0x19

0xE000-0xE3FF

1k Window to Packet with PNR=0x18

0xDC00-0xDFFF

1k Window to Packet with PNR=0x17

0xD800-0xDBFF

1k Window to Packet with PNR=0x16

0xD400-0xD7FF

1k Window to Packet with PNR=0x15

0xD000-0xD3FF

1k Window to Packet with PNR=0x14

0xCC00-0xCFFF

1k Window to Packet with PNR=0x13

0xC800-0xCBFF

1k Window to Packet with PNR=0x12

0xC400-0xC7FF

1k Window to Packet with PNR=0x11

0xC000-0xC3FF

1k Window to Packet with PNR=0x10

0xBC00-0xBFFF

1k Window to Packet with PNR=0x0F

0xB800-0xBBFF

1k Window to Packet with PNR=0x0E

0xB400-0xB7FF

1k Window to Packet with PNR=0x0D

0xB000-0xB3FF

1k Window to Packet with PNR=0x0C

0xAC00-0xAFFF

1k Window to Packet with PNR=0x0B

0xA800-0xABFF

1k Window to Packet with PNR=0x0A

0xA400-0xA7FF

1k Window to Packet with PNR=0x09

0xA000-0xA3FF

1k Window to Packet with PNR=0x08

0x9C00-0x9FFF

1k Window to Packet with PNR=0x07

0x9800-0x9BFF

1k Window to Packet with PNR=0x06

0x9400-0x97FF

1k Window to Packet with PNR=0x05

0x9000-0x93FF

1k Window to Packet with PNR=0x04

0x8C00-0x8FFF

1k Window to Packet with PNR=0x03

0x8800-0x8BFF

1k Window to Packet with PNR=0x02

0x8400-0x87FF

1k Window to Packet with PNR=0x01

0x8000-0x83FF

1k Window to Packet with PNR=0x00

0x0000-0x7FFF

32K Window to External ISA RAM

The actual packet may be composed of up to 10 different 128 byte non-contiguous packets, but the MMU re-maps

the internal addresses automatically such that the 8237 and 8051 only need to reference the packet number and

offset within the packet. For example, suppose a 312 (0x138) byte packet is received by the SIEDMA from the host.

The patented MMU allocates 384 bytes for the packet (including an 8 byte status header) and returns a PNR tag of

0x0A. The SIEDMA engine will place 0x0A in the receive packet queue and notify the 8051. The 8051 will take that

PNR, examine the packet through its own PNR/Pointer registers, and determine the offset for the payload data it

wants to transfer from the packet, say 0x027. The address it must calculate for the 8237 base address register would

therefore be 0xA827 (0xA800+0x027). Each channel can be programmed with a different (or same) Packet Number

and offset and the data will appear to it as ordinary contiguous RAM (see table 32 for more information).

Software written to this model will work for virtually any Endpoint number and Buffer size combination.

USB97C100QFP Datasheet(PDF) 30 Page - SMSC Corporation

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