Dima Veselov wrote in <Zoz2CnYeglHqoxbm@gloria>: |>> Greetings! |>> |>> I wonder is there a way to know blocksize of |>> CD-ROM? I have a number of old machines required |>> to use 512-byte SCSI CD-ROM and I want to ensure |>> 512-byte mode is enabled or supported. |>> |>> I tried atactl and it shows wrong block size, |>> always reporting 512, >> even on certainly 2k |>> CD-ROM. |> |> This mostly matters for the firmware and for |> booting from CD-ROM. The physical media is always |> 2048 byte sectors but some drives can enable |> emulated 512-byte access with the SCSI MODE |> SELECT command. Good drives for both Sun and |> DEC are the Toshiba XM series. |> These resources might be useful: | |Thank you for the answer. I guess real question |was then - how one can find that drive is able tp |emulate 512-byte access? Is it possible to question |SCSI or test it somehow in the running system?
I have used SCSI-mmc3r10g.pdf to implement my s-cdda.c. It says "512 is obsolete", but also says The block descriptor associated with the Mode Select and Mode Sense commands is used for legacy system support. If supported, block sizes (see Table 343.) shall include 2 048 and may include 512, 2056, 2 324, 2 332, 2 336, 2 340, 2 352, 2 368, and 2448 bytes. Table 343 shows the implementation of the various block sizes. These definitions apply for all READ commands. For READ (6), READ (10), READ (12) when Block Descriptors are not supported, block size shall be 2 048. Other block sizes are allowed and the contents of the blocks are not specified by this standard. Table 343 – Block Descriptor Block Sizes for Read Bytes Readable block types 512 Mode 1 or Mode 2 Form 1 sectors divided into four blocks each SCSI-mmc3r10g.pdf can be searched for free. (I could give you an URL if all else fails.) --steffen | |Der Kragenbaer, The moon bear, |der holt sich munter he cheerfully and one by one |einen nach dem anderen runter wa.ks himself off |(By Robert Gernhardt)
