A new release for the original minimig board

Two bugs were discovered and fixed for the original minimig board, and a new release was prepared.

The first bug was in the minimig blitter implementation, which was missing an undocumented feature of the original Amiga chipset. When using the blitter in line mode, the first pixel of the line is written to D pointer address, and all subsequent pixels are written to C pointer address. This bug was obvious in demos like SushiBoyz & Sunglasses by Ghostown, Vectorize by RSi, etc.

The second bug was a special undocumented feature of Denise / Agnus when number of bitplanes in BPLCON0 is set to 7. In this case, Denise enables six bitplanes, but Agnus DMA sequence only fetches four bitplanes. This way, the remaining two bitplanes can be updated ‘manually’ with CPU / Copper writes. This bug was seen in demos like SushiBoyz by Ghostown, Sliced&Diced by Dekadence, etc.

Both fixes, together with my previous addons to the minimig core for the original minimig board are available in the new release minimig-rel4.

Head over to the Original minimig page, grab your copy and enjoy your minimig!


A little update on the minimig core

Quite some time has passed from the last minimig release, so I thought I’d write a short update on what’s going on.

The work on minimig-mist aga v1.2 is progressing, albeit slowly, since I don’t have much free time right now. Here are some of the fixes already implemented and in testing:

  • video dithering (both random and spatial) have been fixed – the dithering didn’t work at all before
  • scanlines can now be enabled in non-scandoubled mode
  • CPU cache control with the CACR register implemented
  • fixed reset problems and fast RAM disappearing
  • kickstart ROM is also uploaded to kickstart mirror position (E0)

Two chipset bugs were also discovered and fixed. The first one was a sprite colortable lookup problem, which was sometimes apparent as a missing sprite line, or wrong sprite color (see here for an example: https://www.youtube.com/watch?v=HD5znZGIvP4). This one was very hard to track down – it required single stepping through the frame with WinUAE debugger, but very easy to fix. The other one was a blitter line mode problem (see http://www.a1k.org/forum/showpost.php?p=904090&postcount=54), that was just the opposite – very easy to track down, and harder to fix.

Till Harbaum has made some updates to the CPU bitfield instructions, that fixes *a lot* of games and demos. There are still some stability problems with the CPU, I’m working on ways to fix that.

Besides that, a few other changes are still planned for the 1.2 release:

  • programmable display modes (Productivity, DblPAL/DblNTSC, Euro36/Euro72)
  • HELP button fix
  • ethernet support (hopefully!)

I think I still need a week or two before the release will be ready. I’ll keep you updated!

minimig AGA v1.1 for the MiST board released

There is a new release of minimig-AGA for the MiST board available, grab your fresh copy on the minimig-mist page!

Here are the updates made in this release:

  • fixed mouse issues (fixes games Like Ishar 1, 2, 3, Robinson’s Requiem, and many cracktros)
  • fixed keyboard issues (fixes game Walker and probably many others)
  • changes to FPGA clock handling, hopefully this will make a more stable minimig core
  • entering the OSD menu using UP+DOWN buttons on a DB-9 connected joystick has been disabled
  • 1MB kickstart ROM support added (enables you to run AROS ROM or your custom kickstart ROM)
  • firmware now again supports using 256kB kickstart ROMs
  • firmware now again supports using Cloanto AmigaForever encrypted kickstart ROMs