I have a Compaq Pc , and when I start , it says 301 keyboard error . I tried another keyboard but the same situation . I made a CMOS reset , moving a jump on the motherboard ,but no result . Can anybody tell me what can I do yet Thanks in advance

What is the exact Compaq model?

Is that the full error message? No FF or number string?

This is from a former thread:

301 Keyboard did not respond to software reset correctly, or a stuck
key failure was detected. If a stuck key was detected, the
scan code for the key is displayed in hexadecimal. For
example, the error code 49 301 indicates that key 73, the
PgUp key, has failed (49 hex = 73 decimal).

ff (Keyboard error)
Three common causes for keyboard error are: (i) several keys pressed simultaneously, (ii) keyboard buffer overflow, (iii) parity error on the serial line used by keyboard and keyboard controller for communication. The error reported is ff in scancode mode 1, and 00 in scancode modes 2 and 3. If translation is on, both 00 and ff are translated as ff.

FF Reset, Keyboard sends ACK and waits for system to receive it
then begins a program reset and Basic Assurance Test (BAT).
Keyboard returns a one byte completion code then sets default
Scan Code Set 2.

FF Key Detection Error or Overrun Error for Scan Code Set 2 or 3,
replaces last key in the keyboard buffer if the buffer is full.

Does pressing F1 get you any where? Can you enter the BIOS Setup?

Are you sure your keyboard is in the keyboard PS/2 port and not the mouse port?

Did you try a USB keyboard?