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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: techhusky on February 10, 2026, 04:46:02 PM

Title: A2000 + TF536 + A2091 + SCSI CD-ROM weirdness
Post by: techhusky on February 10, 2026, 04:46:02 PM

My current setup

• A2000 with 2MB CHIP, 3.1 ROM, OS 3.9
• TF536 with 64MB and IDEtoSD as boot drive (scsi.device)
• A2091 SCSI controller with 2MB (2nd.scsi.device)
• Plextor 12X SCSI CD-ROM, termination enabled, configured as ID 5

Essentially, I'd like to use the A2091 for the CD-ROM drive.  I don't really care about speed, I just need it to work from time-to-time.  Initially after installing the A2091, SetPatch was dying with a Software Error/GURU.  I found that disabling the 2MB onboard the A2091 (via jumper) fixed that issue.  I read about all sorts of issues with the TF536 and Zorro II fast ram, so I wasn't surprised.  I have enough fast on the TF536, so that is fine.  CD-ROM transfers are very slow, but they work.

The weirdness:

I'm now at the point where my system will only boot (in a reasonable amount of time) if there is a CD-ROM in the drive on boot.  Without a CD, the system sits for minutes and will eventually boot.  However, after that, when I load a CD in the drive and attempt to mount the CD0, the device will load, but it will not show up as a volume.  I'm assuming there is some ready signal from the CD-ROM that the A2091 requires.

I tried variations of the auto-boot enable/disable jumper on the A2091.  If auto-boot is disabled the system boots quickly, but when I mount the CD0 device, the device loads, but it will not actually mount the volume.

In short, if I leave a CD in the drive, have auto-boot enabled on the A2091, I can mount CD0 and the volume/media is accessible.  No CD in the drive on boot, no volume/media is accessible after inserting a CD and loading CD0.  With auto-boot disabled on the A2091, I can't mount the volume after boot.

It seems like I need to be able to re-initialize/re-scan the A2091 after the system is up?  Boot-up time is longer when there is a CD in the drive, so I'm really hoping to eliminate that requirement.  Note: I always manually mount the CD0 device so I don't use up buffers and stare at the unused volume on the desktop for 99% of the time I don't need it.

Any ideas?  I appreciate the help.

-Jeremy