Toshiba 4006GAH ユーザーズマニュアル

360050398 

 

Toshiba Corporation Digital Media Network Company 

 

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          Ultra DMA protocol is used with Read DMA, and Write DMA commands. Ultra DMA modes are set by Set 

features command. Since the setting after power-up ( Default setting ) is mode 2 of Multi Word DMA, Set 
Features command shall be issued to be used in Ultra DMA mode. 

          An Ultra DMA data transfer is accomplished through a series of Ultra DMA data in or data out bursts. Each 

Ultra DMA burst has three mandatory phases of operation: the initiation phase, the data transfer phase, and 
the Ultra DMA burst termination phase. An Ultra DMA burst is defined as the period from an assertion of 
DMACK- by the host to the subsequent negation of DMACK-. A recipient shall be prepared to receive at 
least 2 data words.   

          Both the host and drive perform a CRC function during an Ultra DMA burst. At the end of an Ultra DMA 

burst, the drive compares its CRC data to the data sent from the host. The drive requires an Ultra DMA 
burst termination for each sector to compare CRC data to the data sent from the host. 

1. Initiation phase 

a) An Ultra DMA burst initiation phase begins with the assertion of DMARQ by the drive and ends when the 

sender generates a STROBE edge to transfer the first data word. 

b) An Ultra DMA burst is always requested by a drive asserting DMARQ. 
c) A host indicates it is ready to initiate the requested Ultra DMA burst by asserting DMACK-. 
d) A host shall never assert DMACK- without first detecting that DMARQ is asserted. 
e) For Ultra DMA data in bursts: a drive may begin driving DD(15:0) after detecting that DMACK- is 

asserted, STOP negated, and HDMARDY- is asserted. 

f) After asserting DMARQ or asserting DDMARDY- for an Ultra DMA data out burst, the shall not negate 

either signal until the first STROBE edge is generated. 

g) After negating STOP or asserting HDMARDY- for an Ultra DMA data in burst, a host shall not change the 

state of either signal until the first STROBE edge is generated. 

     
2. Data transfer phase   
a) The data transfer phase is in effect from after Ultra DMA burst initiation until Ultra DMA burst termination. 
b) A recipient pauses an Ultra DMA burst by negating DMRDY- and resumes an Ultra DMA burst by   

reasserting DMARDY-. 

c) A sender pauses an Ultra DMA burst by not generating STROBE edges and resumes by generating 

STROBE edges. 

d) A recipient must not signal a termination request when a sender stops generating STROBE edges. In the 

absence of a termination from the sender, the recipient should always negate DMARDY- and wait the 
required period before signaling a termination request. 

e) A sender may generate STROBE edges at greater than the minimum period specified by the enabled 

Ultra DMA Mode . The sender should not generate STROBE edges at less than the minimum period 
specified by the abled Ultra DMA Mode. A recipient should be able to receive data at the minimum 
period specified by the enabled Ultra DMA Mode.