exxos's Atari, Amiga & retro forum

Posted: **11 Apr 2026 20:12**

@Cosmos (a well known French Amiga hardware and software hacker) is taking upon himself to begin modifying Atari Falcon TOS starting with 4.04

He says he intends to patch in all known bug fixes currently patched after booting as well as removing dead code and making it 040/060 safe.

He's made numerous releases with documented "fixes" and is looking for advice/feedback for other known bugs to remove. If you've got a working knowledge of this then get in touch with him.

This comes shortly after the release of his 1MB TOS ROM adapter based on his previous Amiga work.

https://blogatari.blogspot.com/

Code: Select all

Short:        new Tos 4.11 for the Falcon 030
Author:       Cosmos68k
Uploader:     cosmos.amiga@gmail.com
Requires:     Falcon 030 and eprom
Version:      4.11
Architecture: m68k
URL:          http://blogatari.blogspot.com

Tos411.rom beta (512KB)

  - fix one bug into the blitter routines (Cosmos68k)
  - enable Vasm Opt o+ on all the sources


 Tos410.rom beta (512KB)

  - enable Vasm Opt o1+ on all the sources
  - enable Vasm Opt og+ on all the sources
  - many tiny subroutines inlined


 Tos409.rom beta (512KB)

  - fix _d_opnvwk (Markus Heiden)
  - fix number of XBIOS functions into __XBIOS_vecs (Markus Heiden)
  - fix more precise FPU cookies (Dirk Katzschke)
  - replaced five movep by full 030/040/060 code (Cosmos68k)
  - removed all useless "bra *+4"
  - all "tst.l (sp)+" replaced by faster "addq.w #4,sp"
  - all changes still fully compatible with Hatari


 Tos408.rom beta (512KB)

  - realtime debugging completely removed
  - all changes still fully compatible with Hatari


 Tos407.rom (512KB)

  - fix accessing gl_mnpid as LONG instead of WORD (Atari source)
  - fix arg have2box in _gr_draw (Cosmos68k)
  - fix innerloop bug into _oAP32Line (Cosmos68k)
  - fix innerloop bug into _oAP16Line (Cosmos68k)
  - fix innerloop bug into _oAP8Line (Cosmos68k)
  - fix innerloop bug into _oAN32Line (Cosmos68k)
  - fix innerloop bug into _oAN16Line (Cosmos68k)
  - fix innerloop bug into _oAN8Line (Cosmos68k)


 Tos406.rom (512KB)

  - added 'version 4.06' into "Desk/Desktop Info..."
  - fix sound init (FPATCH2.PRG)
  - fix Bconmap() (FPATCH2.PRG)
  - fix wrong stackpointer into _autoscan (Markus Heiden)
  - fix accessing bootdev as byte instead of word (Markus Heiden)
  - fix three d3-d4 movem.w bugs instead of movem.l into _SetOverlay (Cosmos68k)
  - fix wrong arg .flag into _SetOverlay (Cosmos68k)
  - fix four wrong arg .menu +2 at the end of _mn_getmn (Cosmos68k)
  - fix missing return TRUE into _rsc_read (Atari source)
  - fix clearing pb_mask as word instead of long into _bscr_dump (Atari source)
  - fix save transmitter status bug into _iorecout (Atari source)
  - fix two -1 bugs into _initscc (Atari source)
  - fix wrong dbmi instead of dbf into _beg (Atari source)
  - fix 19 wrong instruction encoding (Cosmos68k)


 Tos405.rom (1024KB)

  - added a bsr call beyond the original 512KB rom area
  - revision updated
  - date updated
  - checksum updated


 Note

  - the 1MB version 4.05 is built only for checking Romy is working or not
    you need the small Rom adapter installed on the Falcon PCB and a 27C800
    more informations here :
    https://blogatari.blogspot.com/2025/11/romy-falcon-tos-1mb-adaptateur.html

  - since the version 4.06, you can remove FPATCH2.PRG from your AUTO folder

  - since the version 4.08, you must do a backup of your HD because of large
    unused code removed


 Installation

  - you need a HN27C4096CC at 100ns or lower from Hitachi, take an UV erasable
    with a window on top

  - never had a Falcon, don't know if you will need to 16bit swap my file or
    not before flashing. You must read the original rom and see if it's swapped
    or not : with a hex editor, go at the address $00057000 and see if the text
    is well readable. If yes, you don't need to swap. If no, you need to swap

  - remove the orignal rom from his PLCC socket and put the new flashed eprom

  - be careful at the pin 1

P.S. I've not tried it. I just find his work interesting. His enthusiasm is fantastic and he's a very knowledgeable guy.

Posted: **12 Apr 2026 01:10**

There was some discussion about his over on Atari-Forum a while ago: https://www.atari-forum.com/viewtopic.php?t=45703

Posted: **12 Apr 2026 02:21**

don_apple wrote: 12 Apr 2026 01:10 There was some discussion about his over on Atari-Forum a while ago: https://www.atari-forum.com/viewtopic.php?t=45703

Oh man.. So after reading that thread I'm more confused than I was before.

I also seems my mirror got mentioned. I made that mirror for own personal use as the original site kept going down. It was never even mentioned as a official mirror or linked anywhere on my mirrorpage. So don't know how people even found it in the first place. I generally only publish mirrors when the original site has gone.

exxos's Atari, Amiga & retro forum

Cosmos68k takes on TOS 4.xx

Cosmos68k takes on TOS 4.xx

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