What does 128M mean?

Question

Reading configuration files, like my.cf, I am seeing this:

This is for a system with little memory (32M - 64M) where MySQL plays

What does the M mean in general, and what kind of measurement unit is it in? Does it refer to a megabyte which has the value of 1024?

If a machine has 1 gigabyte of ram how much M is that?

Answer 1

M means megabyte.

1 T(terabyte) = 1024 gigabytes

1 G(gigabyte) = 1024 megabytes

1 M(megabyte) = 1024 kilobytes

1 K(kilobyte) = 1024 bytes

Answer 2

1 byte (B) = 8 bits 1 KB = 1024 bytes = 2^10 bytes 1 MB = 2^10 KB = 2^20 bytes 1 GB = 2^10 MB = 2^30 bytes