Project romdisk - Boot your Amiga from ROM

Written by Christian Vogelgsang under the GNU Public License V2

This projects provides a romdisk.device you can place in an Amiga Kickstart or external ROM. It will autoboot a disk image that is stored next to the device directly in the ROM. You can either store a raw OFS /FFS disk image (ca. 500 KiB size) or a compressed image that holds up to a whole Amiga disk (ca. 880 KiB size). While the raw storage is ultra fast, the compressed images allow you to deploy whole disks into ROM.

Additionally, a tool for modern systems is available that allows you to create those romdisk image easily from existing .adf disk images or from a directory of files.

Why?

Create boot ROMs for

• Diagnosis
• Network Boot
• Quick Startup
• Device-less Amiga Setups
• stripped down Amiga OS ROMs that do not use any external devices during boot (simplifies emulation)

and

• use them in your favorite Amiga emulator
• soft-kick'em in your accelerator card
• flash or burn them to ROMs

Features

• Store raw or compressed disk images
• Compressions supported:
  • Deflate Compression from ZLib
  • RNC Compressor (Rob Nothern Computing)
  • LZ4 Fast Compression
• Autoboot on OS 2.x and 3.x
• Configurable image geometry, boot priority
• Python tool mkromdisk to create image file from disk images or directories
• Amiga device with source that can be cross-compiled on modern systems
• A drop-in replacement variant for trackdisk.device to have a very compatible DF0 device

Prerequisites

• Amiga OS 2.x or 3.x and real/emulated classic Amiga m68k system
• Python 2.7 for host tool
• amitools installed for xdftool, romtool, and vamos
• ppami.exe Amiga tool from RNC ProPack to use RNC Compression
• lz4 tool from lz4.org to use LZ4 Compression
• Cross compilers from amigaos-cross-toolchain to build device from sources

Tutorial

Here is a quick wrap-up on how to create and run a ROM with a romdisk:

• First create a Kickstart ROM that supports an external ROM with additional 512 KiB storage. We use amitool's romtool to convert a A1200 Cloanto OS 3.1 to support 1 MiB ROMs:

romtool patch -o kick.rom miga-os-310-a1200.rom 1mb_rom

• Now run romdisk's mkromdisk tool to create a romdisk image from a disk image. We use the Workbench 3.1 disk from Cloanto's Amiga Forever distribution here (its called amiga-os-310-workbench.adf):

./mkromdisk -i amiga-os-310-workbench.adf -f dflt wb31.rodi

• Finally, create an external ROM image with romtool that contains the romdisk.device (release version) and your romdisk image wb31.rodi:

romtool -v build -o ext.rom -t ext romdisk.device_rel wb31.rodi

• Voila! Your ROM set is ready to be run. You can either use the two files directly (e.g. in your emulator) or combine them to a single 1 MiB ROM file if your soft-kicker needs that:

romtool combine -o 1mb.rom kick.rom ext.rom

• Run the ROM set in the FS-UAE emulator with a configuration like this one (e.g. in a test.fs-uae file):

[config]
amiga_model = A1200
kickstart_file = kick.rom
kickstart_ext_file = ext.rom

If you run the emulator it will boot the Workbench directly from ROM...

More Documents

• romdisk Examples
• romdisk Benchmarks
• mkromdisk Manual

Thanks

• Krystian Bacławski for the great amigaos-cross-toolchain
• Keir Fraser for releasing the deflate m68k source
• Frank Wille for vasm and porting the deflate source to vasm
• Rob Northern Computing for releasing its Pro Pack including source