pdp10: command not found

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 Debian possible default full paths are:

/usr/bin/pdp10 - from package: simh

You may install the required package with command apt-get install {package}

Error in other languages:
pdp10: bevel nie gevind nie
pdp10: comandă negăsită
pdp10: comando não encontrado
pdp10: commande introuvable
pdp10: command not found
pdp10: käsku ei ole
pdp10: không tìm thấy lệnh
pdp10: komanda nerasta
pdp10: Kommando nicht gefunden.
pdp10: kommandot finns inte
pdp10: komut yok
pdp10: nie znaleziono polecenia
pdp10: níor aimsíodh an t-ordú
pdp10: no se encontró la orden
pdp10: no s'ha trobat l'ordre
pdp10: opdracht niet gevonden
pdp10: parancs nem található
pdp10: perintah tidak ditemukan
pdp10: príkaz nenájdený
pdp10: příkaz nenalezen
pdp10: команда не найдена
pdp10: командата не е открита
pdp10: 命令找不到
pdp10: コマンドが見つかりません