Difference between revisions of "OSWORD &FB"

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(Rewrote transaction description.)
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[[Category:OSWORD]]
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[[Category:OSWORD]][[Category:Second Processors]]__NOTOC__
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OSWORD &FB (251) - WD1770/2 Floppy Disk Control 80x86 DOS
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{{PageTitle|OSWORD &FB (251) Floppy disk access}}
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This OSWORD call is installed by the 80x86 DOS BIOS.
  
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The control block is ignored, so for speed, set XY?0=0 and XY?1=0.
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Commands are sent from the 80x86 via Tube Register 2 within the OSWORD protocol,
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Commands are sent from the 80x86 via Tube register 2. These are:
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so cannot be called through the normal OSWORD mechanism. The transaction must be
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0 - Finish
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done manually by the client by sending through Tube Register 2:
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1 - Master FDC command; register 2 sends 4-byte address low to
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    &08 : Start OSWORD transaction
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    high, R/W command, Write flag, Interrupt mask, number of
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    &FB : OSWORD call &FB
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    sectors, FDC command.
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    &00 : TxLen=0
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2 - BBC B/B+ command; as for command 1.
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    xxx : Send a series of commands
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3 - Claim Tube and NMI.
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    &00 : RxLen=0, terminate the OSWORD call
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4 - Release Tube and NMI.
 
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5..&FF - Write byte sent though register2 to &FExx.
 
  
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==See Also==
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===Commands===
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* http://mdfs.net/Docs/Comp/BBC/Oswords
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* &00 : Finish
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* &01 : Master FDC command
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* &02 : BBC B/B+ command
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* &03 : Claim Tube and NMI
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* &04 : Release Tube and NMI
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* &nn,&mm : Write byte &mm to &FE00+nn
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===FDC commands===
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The FDC commands &01 and &02 are followed by a parameter block:
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* address b0-b7
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* address b8-b15
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* address b16-b23
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* address b24-b31
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* &00=Read from disk, <>&00-Write to disk
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* error mask
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* sector count
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* FDC command
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The initial drive, track, sector must be written to the FDC hardware beforehand
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using commands &gt;&04 to write to &FE00+FDC_address.
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==See also==
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* [[OSWORD &FA]]
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* [[OSWORD &FC]]
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* [[OSWORD &FD]]
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* [[OSWORD &FE]]
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* [[OSWORD &FF]]
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* [http://mdfs.net/Software/Tube/Utils/ OSWORD &FB source code]
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* [http://mdfs.net/Docs/Comp/BBC/Oswords OSWORDs list at mdfs.net]
  
 
[[User:Jgharston|Jgharston]] 14:27, 26 May 2009 (UTC)
 
[[User:Jgharston|Jgharston]] 14:27, 26 May 2009 (UTC)
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[[User:Jgharston|Jgharston]] ([[User talk:Jgharston|talk]]) 10:54, 17 December 2024 (CET)

Revision as of 10:54, 17 December 2024

OSWORD &FB (251) Floppy disk access

This OSWORD call is installed by the 80x86 DOS BIOS.

Commands are sent from the 80x86 via Tube Register 2 within the OSWORD protocol, so cannot be called through the normal OSWORD mechanism. The transaction must be done manually by the client by sending through Tube Register 2: 

   &08 : Start OSWORD transaction
   &FB : OSWORD call &FB
   &00 : TxLen=0
   xxx : Send a series of commands
   &00 : RxLen=0, terminate the OSWORD call

Commands

  • &00 : Finish
  • &01 : Master FDC command
  • &02 : BBC B/B+ command
  • &03 : Claim Tube and NMI
  • &04 : Release Tube and NMI
  • &nn,&mm : Write byte &mm to &FE00+nn

FDC commands

The FDC commands &01 and &02 are followed by a parameter block:

  • address b0-b7
  • address b8-b15
  • address b16-b23
  • address b24-b31
  • &00=Read from disk, <>&00-Write to disk
  • error mask
  • sector count
  • FDC command

The initial drive, track, sector must be written to the FDC hardware beforehand using commands >&04 to write to &FE00+FDC_address.

See also

Jgharston 14:27, 26 May 2009 (UTC) Jgharston (talk) 10:54, 17 December 2024 (CET)

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