Larger ROM disks for up to 4 MB Kickstart ROMs (as supported by cosmos' Romy)

[tkurbad]

Hi,

would it be possible to add support for larger than 1MB ROM files? I'm asking because I'm about to get the 4 MB Romy for my A4000T and would like to have a basic system besides several other rom-able stuff in the Kickstart.

Thanks in advance and best,
Torsten

References:
http://eab.abime.net/showthread.php?t=88182
http://leblogdecosmos.blogspot.com/2017/07/kickstart-2-mo-a4000d.html

[cnvogelg]

What is the layout of such a large ROM? Are there multiple smaller ROM layouts concatenated?
To store a romdisk file system there you will need a continous stride of ROM for its storage. It does not work if ROM borders are in between...

[tkurbad]

To be honest, I thus far didn't create such a large ROM. But if I understand SpeedGeek's post on EAB, it works by concatenating a standard 512kB ROM and a 3,5MB extended ROM. So, yes, you'd have all of the space in one stride.

Here's a picture someone took of a successfully created 3.5 MB extended ROM with SpeedGeek's 4MB patch http://eab.abime.net/attachment.php?attachmentid=54428&d=1504309897

So, it should definitely be one large hunk. The possibilities this creates in conjunction with your romdisk are enormous...

[reinauer]

Amiga 3000/4000 with ROMY 4MB GAL:
0x1000000 - 0x13FFFFF 4MB image (3584K + 512K KICKSTART)
0x0F80000 - 0x0FFFFFF (512K KICKSTART)

On the A1200 it seems that a 2MB ROM is mapped to 3 non-consecutive places instead of just 2:

0xA80000 - 0xAFFFFF (512K)
0xB00000 - 0xB7FFFF (512K)
0xE00000 - 0xE7FFFF (512K)
0xF80000 - 0xFFFFFF (512k KICKSTART)

For 1MB ROMY GALs and 1MB A1200 situations it looks like this:
0xE00000 - 0xE7FFFF (512K)
0xF80000 - 0xFFFFFF (512k KICKSTART)

So, while there is a feasible 1MB solution for all Amigas (more or less, with some hardware mods), there would need to be two solutions for 4MB ROMs. I have done this analysis with Rev10/Rev11 ROMY GALs. For further analysis having Rev13 ROMY GALs available would be rather helpful.