Compaq W4000 Manual De Usuario

Technical Reference Guide 

 

5.3.1  DISKETTE DRIVE PROGRAMMING 

 
Programming the diskette drive interface consists of configuration, which occurs typically during 
POST, and control, which occurs at runtime. 
 

 
The diskette drive controller must be configured for a specific address and also must be enabled 
before it can be used. Address selection and enabling of the diskette drive interface are affected by 
firmware through the PnP configuration registers of the 47B357 I/O controller during POST. 
 
The configuration registers are accessed through I/O registers 2Eh (index) and 2Fh (data) after the 
configuration phase has been activated by writing 55h to I/O port 2Eh. The diskette drive I/F is 
initiated by firmware selecting logical device 0 of the 47B357 using the following sequence: 
 
1.  Write 07h to I/O register 2Eh. 
2.  Write 00h to I/O register 2Fh (this selects the diskette drive I/F). 
3.  Write 30h to I/O register 2Eh. 
4.  Write 01h to I/O register 2Fh (this activates the interface). 
 
Writing AAh to 2Eh deactivates the configuration phase. The diskette drive I/F configuration 
registers are listed in the following table: 
 
Table 5–4.   Diskette Drive Controller Configuration Registers 
 

 

 

 

      

                Diskette Drive Interface Configuration Registers 

30h Activate 

R/W 

01h 

60-61h 

Base Address  

R/W 

03F0h 

70h  

Interrupt Select 

R/W 

06h 

74h 

DMA Channel Select 

R/W 

02h 

F0h DD 

Mode 

R/W 

02h 

F1h DD 

Option 

R/W 

00h 

F2h DD 

Type 

R/W 

FFh 

F4h DD 

0 

R/W 

00h 

F5h DD 

1 

R/W 

00h 

 
For detailed configuration register information refer to the SMSC data sheet for the LPC47B357 
I/O component.  
 

 
The BIOS function INT 13 provides basic control of the diskette drive interface. The diskette 
drive interface can be controlled by software through the LPC47B357’s I/O-mapped registers 
listed in Table 5-5. The diskette drive controller of the LPC47B357 operates in the PC/AT mode 
in these systems.  
 

 

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