Re: CD-ROM block size

[Tobias Nygren <tnn%NetBSD.org@localhost>]

On Mon, 8 Jul 2024 15:34:53 +0300
Dima Veselov <kab00m%lich.phys.spbu.ru@localhost> wrote:

> 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:

https://web.archive.org/web/20050110004406/http://narpes.com/aw/vax/dec-cdrom-list.txt
https://web.archive.org/web/20220830171707/http://www.computeranddata.com/doc/faq/cdrom/suncds.html

-Tobias