How to put jumpers correctly?

Question

Iron

Good evening!
Tell me, I’ve been using only a laptop for 10 years, I forgot how to put jumpers on the old hardware correctly? I have a very old hard drive, if you boot only from it - everything is ok. There are no jumpers on the hard drive. I took a CD-ROM, because. It can't read a flash drive, there is a jumper on the CD-ROM, it's on the slave - at startup it says that there is no disk. I put a jumper from the CD-ROM on the hard one on the master - the same way.
Remind me what's what.

Answer 1

Master and slave are modes of operation on the same loop. If your HDD and CD-ROM hang on different cables, then both jumpers should be in the master position (sometimes there is a single position). If the device does not plow, you need to look in the BIOS, if it is not visible there, then it has come to kirdyk (well, or a bad cable).

Answer 2

Made a jumper out of wire. It worked with the SD card, the master is hard.

Answer 3

It should be drawn on the case.
Jumpers may well be required on both devices.
It is important on which part of the cable both devices are located.