Ultimate firmware 3.15 rewrote the SoftIEC implementation and added CMD-HD-style partitions to it. UBoot64 v2's 3.0.0 release added support for that, and the following 3.0.1 release fixed a set of compatibility issues found while testing against the subsequent 3.15a firmware and against real SD2IEC hardware.
What Partitions Add
Before firmware 3.15, the Ultimate's own SoftIEC drive exposed only a single, fixed RAM disk when browsed over the classic IEC bus, with the real USB storage reachable only through the UII+'s own UCI protocol. Firmware 3.15 lets that SoftIEC drive expose CMD-HD-style partitions instead, each pointing at an arbitrary path, browsable and selectable the same way a real CMD hard drive's partitions are on genuine 1541/1571/1581 hardware or an SD2IEC.
UBoot64 v2 3.0.0 adds a partition browser: pressing F4 while in IEC mode lists the device's partitions, and selecting one switches into it. Pressing DEL at a partition's own root returns to that list rather than trying to leave the device entirely. Since this is a generic IEC feature and not an Ultimate-specific one, it works the same way on any IEC device that reports partitions, not only the Ultimate's own SoftIEC drive.
An opt-in "SoftIEC root partition" toggle (config menu, F8) auto-creates a partition exposing the whole USB filesystem at root the next time IEC mode is entered, useful for anyone who has not set up a partition of their own. Menu slots can now record and restore a specific partition at boot, alongside the existing directory path.
3.0.0 also adds automatic UCI enabling from the cartridge itself, so UCI no longer needs to be turned on manually in the Ultimate's own menu before UBoot64 can use it.
Firmware 3.15a Fixes
Firmware 3.15a is a bugfix-only point release, and comparing its commits against 3.15 directly (rather than relying on release notes) showed exactly one change relevant to UBoot64: a rewrite of the SoftIEC command channel parser changed what a partition listing's quoted name field contains, from the partition's root path to its configured display name. UBoot64's check for "is this reserved partition already ours" compared against the old, path-based value, so on 3.15a it always concluded someone else's partition was in the way and refused to auto-create its own. 3.0.1 fixes the check to recognize both forms.
Testing that fix surfaced an older, unrelated bug: UBoot64's saved slot paths for SoftIEC and VICE devices used a single leading slash. Ultimate firmware treats a single leading slash as relative to wherever the drive currently is, not as absolute from its root -- only a double slash is genuinely absolute. This had worked for years by relying on the drive still being positioned at its root the first time a slot ran; selecting a specific partition first, as the new feature does, no longer guarantees that, so a partition-based slot could fail to find its file. 3.0.1 corrects this to the double-slash form.
Testing on SD2IEC
Since partition support is meant to work on any IEC device that reports partitions, not only the Ultimate's own SoftIEC drive, testing extended to a real SD2IEC as well. That turned up a separate, genuine bug: the "go up one directory" command for non-Ultimate IEC devices sent the wrong byte, which a real SD2IEC drive silently rejected while UBoot64's own idea of the current directory advanced regardless -- causing UBoot64's display and the drive's actual position to disagree, and subsequent navigation to show stale directory content. 3.0.1 fixes this to send the correct byte.
3.0.1 also removes an F8 option to delete UBoot64's auto-created partition again when turning the feature off: testing showed the firmware command for this does not actually remove the partition, and it was not needed regardless, since these partitions only exist in the Ultimate's memory and are cleared by the next power cycle either way.
Upgrading
The slot and config file format changed in 3.0.0 to record partition selection. Existing v2 installations need the included uboot_upd23.prg migration tool run once; installations already on 3.0.0 upgrade to 3.0.1 directly, no migration needed. Full upgrade instructions and the complete changelog are in the README.
Sources and More Information
- UBoot64 v2 on GitHub -- source, releases, and full README
- 1541 Ultimate firmware repository -- firmware source, including the SoftIEC/partition code referenced above
- Firmware 3.15 release notes -- official Ultimate documentation