From: jj4public@gmail.com   
      
   On Tue, 26 Oct 2021 06:40:49 -0700 (PDT), muta...@gmail.com wrote:   
   >   
   > My concern is about the nature of CDROMs which I believe   
   > have variable-length tracks, if not sectors, so I'm not sure   
   > that a scheme can be invented, at the BIOS level, to seek a   
   > fixed number of bytes as opposed to seeing a track number.   
   >   
   > BFN. Paul.   
      
   There should be no problem. From software point of view, CD-ROMs don't have   
   multiple tracks like in harddisks and floppies. In CD-ROMs, track is just an   
   index which is part of a CD-ROM's table of contents. When addressing a   
   sector, track number is not involved at all.   
      
   The lowest level of CD-ROM sector addressing is by time: hh:mm:ss.ff. Where   
   `hh:mm:ss` is hours, minutes, and seconds; and `ff` is frames. There are 75   
   frames per second. Each (raw) frame is 2352 bytes, which is equal to 176,400   
   Bytes. The same audio CD data rate for 44.1KHz 16-bit stereo PCM audio data.   
      
   LBA addressing is just an additional sector address translation which is   
   implemented at disk controller firmware level. Both LBA and time based   
   addressing are flat addressing. When we need to address a sector at   
   beginning of a specific track number, we'll have to refer to the CD-ROM's   
   TOC to get the absolute time/LBA address of a specific track, then we have   
   to use that address (instead of track number) to access the needed sector.   
      
   You might want to refer to t10.org documents regarding CD-ROM and related   
   application interface specifications. i.e. SPC, SBC, MMC, RMC, etc. But I'd   
   suggest you read about ASPI first, as an introductory material.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)