diff --git a/README.md b/README.md
index 698ba11..6d9cd85 100644
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 Booted from a floppy, it will load an Option ROM image into the end of conventional memory.
 
-![PCem IBM XT screenshot](https://b.rvalles.net/unsorted/pcem_ibmxt_optromboot_xtide.png)
+![PCem IBM PC screenshot](https://b.rvalles.net/unsorted/pcem_ibmpc_optromboot_xtide.png)
 
 ## Use cases (non-exhaustive)
 * Test boot ROMs before burning them.
@@ -10,10 +10,12 @@ Booted from a floppy, it will load an Option ROM image into the end of conventio
 * IDE support (including LBA!) with XTIDE Universal BIOS.
 
 ## Highlights
-* flat assembler syntax.
+* Flat assembler syntax.
 * Pure 8086 code.
-* Works on newer hardware, such as the 486 I wrote it for.
 * Fits in a floppy bootblock.
+* Verifies ROM image checksum after loading.
+* Works on PC/XT/AT and clones.
+  * Also works on newer hardware, such as the 486 with AMI BIOS I wrote it for.
 * Trivial to use. Concatenate loader and the ROM image, write into floppy.
 * Makefile will prepare 5.25" 360K/1.2M and 3.5" 720K/1.44M floppy images.
 * MIT License. See LICENSE file.
@@ -21,27 +23,26 @@ Booted from a floppy, it will load an Option ROM image into the end of conventio
 ## Usage
 * Ensure fasm (flat assembler) is installed.
 * Copy your ROM image as the `optrom.bin` file.
-* Optionally test ROM image with qemu: `make emulaterom`.
+  * Ensure the ROM image is signed (has correct checksum).
+    * optromloader will loudly refuse to run the ROM image if not signed.
+    * Test with `make emulaterom`. Qemu's BIOS won't see the ROM if it's not signed.
+    * Qemu provides a python tool to sign ROMs:
+        * https://github.com/qemu/qemu/blob/master/scripts/signrom.py
+    * For XTIDE Universal BIOS ROMs, use its XTIDECFG tool to configure and sign ROM images.
 * Run `make`.
 * Floppy images will be created (fd*.img).
 * Optionally test 1.44M image with qemu: `make emulate`.
 * Alternatively, use a binary release. Concatenate:
-  * optromloader9/15/18 (according to sectors per track in your floppy format).
-    * 9 for 5.25" 360K and 3.5" 720K.
-    * 15 for 5.25" 1.2M.
-    * 18 for 3.5" 1.44M.
+  * optromloader9/15/18, according to sectors per track in your floppy format:
+    * `9` for 5.25" 360K and 3.5" 720K.
+    * `15` for 5.25" 1.2M.
+    * `18` for 3.5" 1.44M.
   * the ROM image.
   * pad to floppy size.
 
 ## Caveats
-* ROM size limited to <= 64KB.
+* ROM size cannot be over 64KB (one 8086 segment).
 * Hardcoded to use the first floppy drive.
-* ROM checksum isn't checked (yet).
-  * Always ensure a boot ROM is signed before burning.
-    * Test with `make emulaterom`. Qemu's BIOS won't see the ROM if it's not signed.
-  * Qemu provides a python tool to sign ROMs:
-    * https://github.com/qemu/qemu/blob/master/scripts/signrom.py
-  * For XTIDE Universal BIOS roms, use its XTIDECFG tool to configure and sign ROM images.
 
 ## Author
 Roc Vallès Domènech