This is a firmware hack of the version 2.6d build for the 1541 Ultimate Plus (MK1) by Bradon (forum link).

The latest official version for the 1541 Ultimate Plus (MK1) is the version v2.4a.

Note from the author:

After much frustration, I finally managed to get a working build environment for the 1541U firmware.

My 1541U is a MK1 Plus unit (no network). The last revision of the firmware I could compile is 2.6d, SVN revision 131. Starting with 132 it seems that the content is too much for the older FPGA. I started to look into removing cart ROMs I don’t use and gave up realizing this would be too much to do in my spare time, since their offset locations are hardcoded.

I removed the “too old” warning check so it will boot up without having to dismiss a warning.

So far it seems to work correctly. I don’t know if the FPGA revision check really matters for this revision or not. It would appear Gideon has no desire to continue supporting MK1 units since building for them is not possible with the latest revisions. This is of course fine with me (I don’t expect he will forever and ever try to make it work on older units), I just wanted the most recent build possible.

Changes:

• Added F3 help screen to show 1541U commands.
• Modified the file viewer so that scrolling will not advance past the last line.
• Added F1 and F7 page up/down to the file viewer.
• Modified behavior of the file browser so that when you cursor-right on an item with no children, the context menu is brought up as if you pressed return.

Download: 1541 Ultimate (MK1) v2.6d.o918r4 (1279)

source: 1541ultimate.net