OK, just wanted to update this thread on my latest SCSI->SD exploration on the AM1400...
I ordered the ZULU 1.1 board from inertial computing:
https://store.inertialcomputing.com/ZuluSCSI-V1-1-p/zuluscsi-v1.1-rev-2022c.htm
FWIW, I ordered the add-ons: Floppy-Style Berg Power Connector and the 3.5 inch Mounting Bracket.
The Floppy-style Berg Power connector connects to one of the 1400's disc-device power cables. It doesn't appear that the 1400 supplies power on the SCSI bus, as far as I could tell.
The Mounting bracket installs beautifully, exposing the SD card slot on the front of the 1400. They also offer a 5.25 inch mounting bracket which may be more appropriate for the AM1000/1200s.
Zulu has a nice feature - you can have multiple disk images on it, and it will mount each as a separate SCSI device. As such I was able to mount several images simultaneously. You simply name them HD0.img, HD1.img, etc. and they'll mount up as SCSI device 0, 1, etc.
You can also mount CD images as either .img files or .iso files.
More detailed info for the Zulu board is here:
http://zuluscsi.com/
The full manual is here:
http://zuluscsi.com/ZuluSCSI-Manual/
and firmware is here:
https://github.com/ZuluSCSI/ZuluSCSI-firmware
The firmware appears to be actively maintained with updates as recent as April 2022.
One other nice feature is that the LED status light will blink to let you know if there's a problem, and an log is written to the sd card that is a txt file that you can view on another machine to see what's going on:
Log files and error indications
Log messages are stored in zlulog.txt, which is cleared on every boot. Normally only basic initialization information is stored, but switching the DBG DIP switch on will cause every SCSI command to be logged, once the board is power cycled.
The indicator LED will normally report disk access. It also reports following status conditions:
- 1 fast blink on boot: Image file loaded successfully
- 3 fast blinks: No images found on SD card
- 5 fast blinks: SD card not detected
- Continuous morse pattern: firmware crashed, morse code indicates crash location
In crashes the firmware will also attempt to save information into zuluerr.txt.
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Overall, I got this up and running in a few minutes... once i found the manual and understood the naming conventions.