README.md: Structure and format better. Add make emulaterom.

Author: rvalles

README.md

@@ -2,39 +2,45 @@
 
 Booted from a floppy, it will load an Option ROM image into the end of conventional memory.
 
-![PCem PC1512 screenshot](https://b.rvalles.net/unsorted/pcem_pc1512_optromboot_xtide.png)
+![PCem IBM XT screenshot](https://b.rvalles.net/unsorted/pcem_ibmxt_optromboot_xtide.png)
 
-Usage
-* Ensure fasm (flat assembler) is installed
-* Copy your ROM image as the `optrom.bin` file.
-* Run `make`.
-* Optionally test with qemu: `make emulate`.
-* Floppy images will be created (fd*.img).
-* 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
-  * the ROM image.
-  * pad to floppy size.
-
-Use cases (non-exhaustive)
+## Use cases (non-exhaustive)
 * Test boot ROMs before burning them.
 * Netboot with etherboot/gpxe/ipxe.
 * IDE support (including LBA!) with XTIDE Universal BIOS.
 
-Highlights
+## Highlights
 * flat assembler syntax.
 * Pure 8086 code.
 * Works on newer hardware, such as the 486 I wrote it for.
 * Fits in a floppy bootblock.
 * 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.
 
-Caveats
+## Usage
+* Ensure fasm (flat assembler) is installed.
+* Copy your ROM image as the `optrom.bin` file.
+* Optionally test ROM image with qemu: `make emulaterom`.
+* 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.
+  * the ROM image.
+  * pad to floppy size.
+
+## Caveats
 * 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