[SPARCbook] 1. SPARCbook 3 external SCSI connector.

[Chase Rayfield]

SD card class ratings were surpassed log ago... many SD cards can do alot more than the requirements of class 10. The limiting factor of the SCSI2SD is the PSOC chip it uses... an FPGA based solution is probably the next step to go faster than SCSI-II (since SD card speed isn't the issue). Also I think an NVMe to SCSI adapter would be pretty ideal... 

https://www.sdcard.org/developers/sd-standard-overview/bus-speed-default-speed-high-speed-uhs-sd-express/
Current gen cards are mostly UHS cards that can do around 100MB/s ... upcoming cards are basically tiny NVMe SSDs... with nearly 4GB/s of bandwidth. 

Chase