Dos not appear while booting

I facing a problem because when I boot up suppose we can see running memory calculation and so on but my PC cannot see all those thing and PC will direct to Windows.

I try to restart in Ms-dos mode also cannot see dos.

Actually I want to openprogram from dos mode program.

My PC is NEC PC98-21 Xa200, OS Win95, program running in dos ver 4.0.

Please assist me to solve this problem.

TQ.