Hello,
I have a DB25 BlueSCSI from tom.scsi.blue, and while it works wonderfully with my Mac Plus, testing with Transoft SCSI Pro 4 finds an access time of consistently about 13 milliseconds. I did some research, and it seems that most quality SD cards have access times of 1 or 2 ms. I have tested both a 32 GB Sandisk Ultra and a 256 GB Samsung EVO Select, both formatted as exFAT, and gotten the same results.
I have a project that needs low access times, because it needs to read small amounts of data from the disk quickly. The "seek time" given by SCSI Director is about 2 ms (totally acceptable), and the read rate is about 430 kB/s. I'm using the r0w0s6 version of SCSI Accelerator.
I dug into the BlueSCSI code and it looks like all file reading is passed through SdFat, so I don't think the slowdown is caused by an issue there. SdFat is a reputable and high-speed library, even over SPI. The cards are also run at 50 MHz consistently.
The Retro Theory Twitter post shows access times of about 1.5 ms, and access time seems like it should be disk-limited, not computer-limited. Is there a solution? Or is this just a limitation of the early SCSI implementation in the Plus?
Hello, I have a DB25 BlueSCSI from tom.scsi.blue, and while it works wonderfully with my Mac Plus, testing with Transoft SCSI Pro 4 finds an access time of consistently about 13 milliseconds. I did some research, and it seems that most quality SD cards have access times of 1 or 2 ms. I have tested both a 32 GB Sandisk Ultra and a 256 GB Samsung EVO Select, both formatted as exFAT, and gotten the same results.
I have a project that needs low access times, because it needs to read small amounts of data from the disk quickly. The "seek time" given by SCSI Director is about 2 ms (totally acceptable), and the read rate is about 430 kB/s. I'm using the
r0w0s6version of SCSI Accelerator.I dug into the BlueSCSI code and it looks like all file reading is passed through SdFat, so I don't think the slowdown is caused by an issue there. SdFat is a reputable and high-speed library, even over SPI. The cards are also run at 50 MHz consistently.
The Retro Theory Twitter post shows access times of about 1.5 ms, and access time seems like it should be disk-limited, not computer-limited. Is there a solution? Or is this just a limitation of the early SCSI implementation in the Plus?