English Amiga Board - Velvet Bootblock

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- - Velvet Bootblock (https://eab.abime.net/showthread.php?t=107746)

banderson38911

25 July 2021 21:31

Velvet Bootblock

Hello,

I've been messing around with/documenting the features of the Kickstart 0.4 ROM in WinUAE and was wondering how to create or modify a bootblock for an ADF so it will run (virtually) on an A1000 "Velvet" system.

Thanks,
-Bernard Anderson

Tomislav

26 July 2021 12:01

Does 0.4 have trackdisk.device? I'm thinking that for earlier betas maybe they used some 720K sized format?!?!
Sadly, 0.4 is not included in AmigaForever, although some people say that Cloanto have it.

Toni Wilen

26 July 2021 12:36

I haven't checked the format but afaik it is something very different than usual Amiga MFM format. Standard ADF won't work, it needs to be extended ADF.

mark_k

26 July 2021 13:54

I think it uses standard trackdisk format.

I made a bootable ADF for it, see this post.

Also a ROM-dumping ADF, see this other post.

Neither was tested on real hardware though.

banderson38911

27 July 2021 01:00

Quote:

Originally Posted by Tomislav (Post 1497884)

Does 0.4 have trackdisk.device?

Yes it does. Albeit with fewer commands.

banderson38911

27 July 2021 01:16

Quote:

Originally Posted by mark_k (Post 1497902)

I think it uses standard trackdisk format.

I made a bootable ADF for it, see this post.

Also a ROM-dumping ADF, see this other post.

Neither was tested on real hardware though.

I downloaded the ADFs and unfortunately they don't seem to work, they boot to the usual black screen with green garbage. The ROM is 128K and starts at $FE0000.

banderson38911

27 July 2021 05:49

Quote:

Originally Posted by Toni Wilen (Post 1497894)

I haven't checked the format but afaik it is something very different than usual Amiga MFM format. Standard ADF won't work, it needs to be extended ADF.

Hello Toni. I think I found the bootblock checksum in Exec. The routine in question is at $FE0400-FE041E in the Kickstart 0.4 ROM.

mark_k

28 July 2021 10:18

Quote:

Originally Posted by banderson38911 (Post 1498014)

I downloaded the ADFs and unfortunately they don't seem to work, they boot to the usual black screen with green garbage. The ROM is 128K and starts at $FE0000.

I could have sworn I tested in WinUAE (using whichever version was current at the time). Could something have changed with WinUAE's velvet emulation since then???

Toni Wilen

28 July 2021 10:35

Works for me. It runs this loop:

Code:

00010000 41f9 00df f180           LEA.L $00dff180,A0

00010006 43e8 fe86                LEA.L (A0,-$017a) == $00dff006,A1

0001000A 317c 4000 ff1a           MOVE.W #$4000,(A0,-$00e6) == $00dff09a

00010010 3091                     MOVE.W (A1),(A0)

00010012 3091                     MOVE.W (A1),(A0)

00010014 3091                     MOVE.W (A1),(A0)

00010016 3091                     MOVE.W (A1),(A0)

00010018 60f6                     BT .B #$f6 == $00010010

mark_k

28 July 2021 19:14

Quote:

Originally Posted by banderson38911 (Post 1498014)

I downloaded the ADFs and unfortunately they don't seem to work, they boot to the usual black screen with green garbage. The ROM is 128K and starts at $FE0000.

Is the WinUAE config you're using set to emulate the Velvet hardware? Just loading the Velvet Kickstart on an A500 (or other retail Amiga) config wouldn't work.

banderson38911

29 July 2021 16:20

Quote:

Originally Posted by mark_k (Post 1498346)

Is the WinUAE config you're using set to emulate the Velvet hardware? Just loading the Velvet Kickstart on an A500 (or other retail Amiga) config wouldn't work.

Yes. I have configured WinUAE for the Velvet hardware and ROM in versions 4.4.0 and 3.1.0.

Which one are you using?

Toni Wilen

29 July 2021 20:22

Did you configure Velvet using Quickstart? It is too easy to get manual config wrong.

Also add -log -serlog to command line, you should see some Velvet ROM debugging messages in log window.

banderson38911

30 July 2021 00:14

Quote:

Originally Posted by Toni Wilen (Post 1498525)

Did you configure Velvet using Quickstart? It is too easy to get manual config wrong.

Also add -log -serlog to command line, you should see some Velvet ROM debugging messages in log window.

No I didn't. Will try that now.

banderson38911

30 July 2021 00:23

Quote:

Originally Posted by banderson38911 (Post 1498555)

No I didn't. Will try that now.

Alright. Configured Velvet in Quickstart and rescanned the ROMS. The ADF to dump the Velvet ROM is doing something. Now after displaying the "green garbage" the background changes to yellow, flashing white, then all lime green.

In other words, I think it works!

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