Author Archives: admin

Discontinutation of U1MB plugin and ‘rapidisk.sys’ driver for Rapidus

Earlier this year, I was informed (by Lotharek) that the U1MB/Rapidus compatibility problems (which have blighted many installations for over four years) have been confirmed to be caused by the Rapidus accelerator itself. The specific cause of said compatibility issue – though apparently observed via tech analytics to be Rapidus itself – remains unknown or undisclosed in any detail, but since it exists, and since the attitude of Rapidus developers still appears to be ‘Works here, so everything is fine’, ‘Your U1MB firmware must be to blame’, ‘the U1MB hardware must be to blame’, ‘Your opinion has no crediblity’, or any one of several other repetitive rebuttals, I have decided to withdraw all Rapidus support from the U1MB firmware and driver collection. This includes the ability to activate and deactivate the Rapidus core in software, and the ability (via the RAPIDISK.SYS driver) to double the HDD bandwidth on SIDE2/XEL-CF systems in the presence of the 20MHz 65C816 CPU.

When I first received Rapidus in 2016, I immediately found it puzzling that the issues I could observe on both stock (with SIDE2) and any randomly selected U1MB equipped machine were regarded as difficult or impossible not only to reproduce, but even to entertain. As a competent hardware installer, it was obvious to me that one statistical certainty is that any other European PAL Atari user with a Rapidus, U1MB and half a dozen Atari machines would be able to replicate the issue if an attention span of more than twenty minutes could be maintained. Nevertheless, my inability or unwillingness to ship a single randomly selected machine from my collection to Poland for ‘diagnosis’ was promoted as the single immovable obstruction in the way of actually finding a solution to the problem. Moreover, I was accused of undertaking a smear campaign against the hardware (for which I nevertheless developed software), constantly criticising the device (the installation of which I repeatedly and in great detail documented on video, presumably advertising the product in the process), and of not wanting the problem to be fixed (regardless of the hours of troubleshooting I undertook and stability fixes I tested).

In December 2020, the U1MB hardware or fimware apparently remains a prime suspect (in the eyes of Rapidus developers) as a cause of problems, regardless of the fact issues were observed with both generations of U1MB firmware, and even with or without U1MB present at all. Moreover, while going about my general business of answering operation queries from users of U1MB/Rapidus combos (since I provide software explicitly to support the interaction of both devices), I cannot do so without being harried, contradicted and fact checked by the Rapidus firmware developer (about whose software contributions to Rapidus I do not even have any complaints; indeed, they deserve nothing but praise). I have therefore chosen to entirely wash my hands of Rapidus, and this means withdrawing all U1MB plugins and drivers related to Rapidus operation. Only by doing this can I wholly avoid involvement in any future discussions of the Rapidus hardware, and thus avoid being drawn into tiresome quarrels or being obligated to provide technical support for problems which no-one can clearly identify or fix.

I realise the Rapidus plugin and HDD accelerator were probably of niche interest, so hopefully the deprecation of both will not cause anyone great inconvenience.

Meanwhile, I will no longer be installing Ultimate 1MB and Rapidus in the same machine, since I consider the combination to be problematic and therefore resistant to any level of quality assurance.

Ultimate 1MB, Incognito, SIDE/SIDE2, 1088XEL/XLD firmware update version 3.10 released

I am pleased to announce the release of version 3.10 of the Ultimate 1MB, Incognito and SIDE firmware, incorporating the recently released SpartaDOS X 4.49, and version 4.0 of the SDX ‘soft-driver’ for SIDE, MYIDE, and Colleen. Updated APT Tools and user documentation are also provided.

What’s New?

As well as several minor bug fixes, this release brings with it numerous performance, stability and usability improvements. Some highlights:

  • Loader’s recursive search speed improved by 25 per cent
  • Optional keyboard/joystick acceleration feature in loader speeds up navigation of long directories
  • Long filename extensions now remain on-screen even while filename is scrolling left to right
  • Card hot-swap reliability improved
  • CF card compatibilty improved
  • ATR swap button now works in loader
  • Loader issue with SD/CF adapters fixed
  • Stereo POKEY detection now compatible with SimpleStereo v3
  • ATR swap button can now be disabled on the Incognito
  • Better boot drive handling (fixes issues with some boot loaders run from FAT-hosted ATRs)
  • Improved DCB error checking in PBI BIOS and support for immediate-mode IO
  • XF551 high-speed SIO bug fixed
  • Regression regarding CONFIG.SYS boot drive setting fixed
  • FDISK large volume/disk bug fixed

Please see the changelogs for the main BIOS, PBI BIOS and SIDE Loader for a complete list of changes.

Download the update here.

SDX 4.49

Thanks to DLT, we have the welcome release of SpartaDOS X 4.49. Unfortunately the ROMs hosted on the official SDX site were put together before I released the updated APT tools and SDX soft-drivers. As ever, however, SDX ROMs for all platforms are included in the new firmware release, with the extra tools I like to provide (notably the LSDEV and LSDSK utilities on the CAR: volume). Note the plethora of ATR disk images I provided in prior updates has been done away with; all ROMs for U1MB and Incognito are included on the corresponding ‘FIRMWARE.ATR’ disk image. This makes the preparation of subsequent updates a little less labour intensive.

Please look at the updated README files in the ZIP archives for complete descriptions of the archive contents.

I hope you enjoy the updated firmware and tools, and as always I welcome feedback including bug reports and feature suggestions (although we are rapidly reaching the end of the road when it comes to available code space on the existing hardware). Donations are likewise welcomed and appreciated, although they are by no means obligatory.

Special thanks to Lotharek at for his continued provision of Candle O’Sin’s fabulous U1MB, SIDE2 and Incognito devices, and for offering my firmware pre-installed at the point of sale. Please continue to support his invaluable efforts.

Important U1MB, Incognito, SIDE and 1088XEL/XLD Firmware Update Released

I’m pleased to announce the release of version 3.02 of the alternative firmware for the U1MB, Incognito, and SIDE/SIDE2. Please visit the firmware page to download new ROMs, drivers, and tools. As well as updated firmware manuals, updated APT documentation may be found on the APT documentation page. Note that this update fixes issues identified in the previous release (3.00) and is highly recommended for all users.  

Ultimate 1MB, 1088XEL/1088XLD, SIDE/SIDE2 and Incognito Firmware Version 3 Released

I’m pleased to announce the release of version 3.00 of the alternative firmware for the U1MB, Incognito, and SIDE/SIDE2. Please visit the firmware page to download new ROMs, drivers, and tools. As well as updated firmware manuals, updated APT documentation may be found on the APT documentation page.

1088XEL U1MB Firmware Released

Ten months after I started work on the custom U1MB firmware for the Mini-ATX 1088XEL, I’m happy to announce its public release. The 1088XEL – paired with the XEL-CF adapter – offers dual-CF card operation, as well as compatibility with SD/CF adapters and SD/IDE adapters. You can download the firmware, user guide and technical documentation from the 1088XEL Firmware Page.

Ultimate 1MB, Incognito and SIDE/SIDE2 Firmware Update

Following on from the previous “September” update, a major re-write of the SIDE Loader culminates in the release of a further firmware update for Ultimate 1MB, Incognito and SIDE/SIDE2. For the first time, the new SIDE Loader is also available as an XEX which can be run from DOS.

The revised SIDE Loader offers a powerful new search facility which is able to scan the entire directory hierarchy for files and folders.

You can download the new update – together with revised documentation – via the firmware section.

Ultimate 1MB, Incognito and SIDE/SIDE2 Firmware Update

After some extensive development work following the previous update, the “final” firmware update for U1MB, Incognito and SIDE/SIDE2 is complete. New features include:

  • Dedicated High-Speed SIO menu
  • SIO2BT support (at up to 56kb/s) and high-speed SIO for PCLink and other serial devices
  • Built-in CIO “Z:” RTC device handler
  • Improved SDX support
  • Rapidus plug-in and support for PBI BIOS extensions in fast linear 65C816 RAM (U1MB only)
  • General SIDE loader improvements

Grab the latest updates from the Firmware section.

New Ultimate 1MB, Incognito Firmware and SIDE/SIDE2 Loader Update

Another firmware update for Ultimate 1MB, Incognito including Main BIOS, PBI BIOS and SIDE XEX Loader, plus updated XEX Loader for SIDE/SIDE2. New features include:

  • Unified user interface for both main BIOS and XEX Loader
  • Improved SIO2BT support
  • High-speed SIO support for PCLink and other serial devices
  • Improved CF card hot-swap handling in PBI BIOS and loader
  • Improvements to keyboard and joystick handling
  • Various bug fixes

The updates (and corresponding documentation) may be downloaded via the firmware page. Please see the heavily revised user manual for details of the new features – in particular the SIO driver section.

Ultimate 1MB, Incognito and SIDE BIOS/Loader Update

New updates for Ultimate 1MB, Incognito and SIDE/SIDE2 may be found in the firmware section of the site. New features include:

  • Loader: joystick operation augmented by console key home, page down and page up navigation keys (primarily aimed at XEGS with keyboard disconnected)
  • Loader: joystick control generally improved with proper debounce and better auto-repeat
  • Loader: position in file or option list now preserved when moving between menus
  • Loader: minor bug fixes
  • Main BIOS: config changes requiring reboot now detected when swapping profiles
  • Main BIOS: dual-level HDD write lock (see below)
  • PBI BIOS: SIO2BT automatically handled by high speed SIO handler (simply enable HSIO for the appropriate drive)
  • PBI BIOS: HDD writes can now be blocked at the partition or physical disk level (meaning writes to the MBR and partition table may be completely blocked once the media is partitioned)
  • PBI BIOS: Patch vectors for RAM-based IO driver code