Today, I have discovered that the Master/Slave problem is not uniform among all old Toshiba laptops.

From my recent experiments:

Toshiba 400CDT would accept only ATAPI slave drive

Toshiba 430CDT would accept both ATAPI master and ATAPI slave.

This is a mess... since 440CDX, 470CDT, 490XCDT, 530CDT and 750 would accept only ATAPI master.

This have made a lot of confusion in my mind 😀 because I thought that problem is solved and all old Toshiba laptops from series 400, 500 and 700 required ATAPI master drives.

Well originally the laptops would have just come with the drives they were shipped with and the part codes were specific to each model, so thank you for cataloguing which Satellite / Tecra likes each mode 😀
I wonder if the 400CDT depends on the BIOS version or if it's just specific to each model? I ask because the 400CDT and 430CDT should be able to share CD-ROM drives, so maybe that's why the 430CDT is okay with Master or Slave, while later models require Master only.