b43-asm: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/b43-asm - from package: b43-tools

You may install the required package with command yum install {package}
Error in other languages:
b43-asm: bevel nie gevind nie
b43-asm: comandă negăsită
b43-asm: comando não encontrado
b43-asm: commande introuvable
b43-asm: command not found
b43-asm: käsku ei ole
b43-asm: không tìm thấy lệnh
b43-asm: komanda nerasta
b43-asm: Kommando nicht gefunden.
b43-asm: kommandot finns inte
b43-asm: komut yok
b43-asm: nie znaleziono polecenia
b43-asm: níor aimsíodh an t-ordú
b43-asm: no se encontró la orden
b43-asm: no s'ha trobat l'ordre
b43-asm: opdracht niet gevonden
b43-asm: parancs nem található
b43-asm: perintah tidak ditemukan
b43-asm: príkaz nenájdený
b43-asm: příkaz nenalezen
b43-asm: команда не найдена
b43-asm: командата не е открита
b43-asm: 命令找不到
b43-asm: コマンドが見つかりません