Raw Machine Code – Opening a file with Read as

Machine code with no header, read as the code of a CPU you choose

Introduction

A file with no header gives the explorer nothing to recognise it by, so it is shown as bytes: the hex view and nothing else. Raw machine code is reached from there by hand, with the Read as list in the bar at the top of the explorer window.

Steps

  1. Drop the file on the page, or choose it. The window opens and shows its bytes.
  2. Optionally press Identify. It tries every format the explorer reads and lists the ones that accept the file; if one is the right one, Read as offers it first. Raw machine code is never among these results: Identify only reports formats the bytes pass a test for, and raw code accepts any bytes.
  3. Open the Read as list. Under the formats that accepted the file, or alone when none did, there is a group called Raw / headerless. It lists every family that reads bytes with no signature to check: raw audio samples, raw machine code, and the headerless ROM families.
  4. Choose Raw machine code. The options bar appears (see the options): choose the CPU family, the CPU and its variant, and set the base address and the entry offset.
  5. Open the Code region in the Raw code tab. Change an option and the disassembly is rebuilt.

What the list does and does not do

  • The Raw / headerless group is always there for a file the explorer has opened, whatever the file is and whether or not a format claimed it. It is a way to look at any file differently, not a verdict.
  • The group always comes after the formats whose own test passed. A file that a format recognises opens exactly as it did before; picking a raw family changes only what you are looking at.
  • No raw family is chosen for you: not by file name, not by extension, not by Identify, not when a file is opened from an archive or a folder. A .bin is opened as bytes until you decide.
  • Read as works on the file that is open, including a file taken out of an archive or disc image. The options you chose for the raw family are remembered for the next file you open in the same window (not after it is closed).

Not described

Known, not yet covered

  • Viewer: the list is made when the window first needs it, from the families that declare themselves raw; a new platform viewer is offered there only after its plug-in is listed as a raw one. The list cannot yet be searched or sorted.

Links

Reference