I finally got one of these cards for a reasonable price (at least, not the $400 they kept going for during the pandemic). I figured I'd document some notes I didn't see anywhere else, or consolidate some bits with scattered misinformation:
- Yes, you can use it as a boot drive. Yes, on a Quadra. No, that does not require a firmware update. My card with firmware 1.6.1 works fine. As noted elsewhere, you have to boot from another disk (floppy works fine) and use Startup Disk to select the correct disk.
- It uses a Qlogic ISP1000, originally designed for SBus, apparently. You can see details on page 3-31 of this product catalog: https://tvsat.com.pl/PDF/F/FAS101.pdf
- ISP is "Intelligent SCSI Processor", it's some form of RISC core.
- Linux firmware contains a newer version of the ISP1000 firmware (though in the wrong endian): 1.31. No idea if it's compatible, or what it improves.
- It contains two onboard 3000-series FPGAs, the bitstreams do not appear in the flash ROM. I've seen pictures with Xilinx 3030s, my device has AT&T 3030s. There's a separate (socketed) 1765DPC which likely contain the bitstreams. I haven't dumped it.
- The ROM contains firmware for the Qlogic SCSI controller as well as a DeclROM. Dumping the ROM from the OS does NOT dump the Qlogic firmware and as a result you get an incomplete image. The DeclROM size does not cover the entire ROM space. This is segmented as follows:
- 1k - Copyright statement, and for the SCSI 4.3 firmware, what may be some data tables.
- 22k - Qlogic controller firmware
- 41k - DeclROM
- The manual claims the flash ROM is 256KiB, but it's only 64KiB.
- It also has 64KiB of onboard SRAM, presumably for cache or command queueing.
- With the original firmware the card substitutes its own disk drivers, ignoring whatever the drive is formatted with. This is because they provide direct access to data through the card and don't present as SCSI at all (this was, presumably, to provide pre-SCSI 4.3 compatibility). The card dynamically installs a driver per card with a name matching the slot and SCSI ID (with a card in slot C, ID 3 is .SiliconExpress_C30). The zero might be for the LUN, I don't have a multi-LUN devices to verify.
- There's some oddities to this, however. It checks to see if a device has been initialized as a disk before installing its driver, so an unformatted disk will not appear. There's some details in the manual about how to configure an uninitialized disk.
- It's a true SCSI bus, it doesn't just support storage. I haven't tried it myself, but it advertises support for SCSI scanners, etc.
- It claims to work in expansion chassis without modification (like Digidesign units).
- The SCSI 4.3 firmware was either never finalized, or the completed version has never been found. Specifically, 2.1rc2 for 4.3 is older than 1.6.5. This can be seen two ways:
- The vendor date on 2.1rc2 is 19-Mar-1996. On 1.6.5 it is 20-Jun-1997.
- The Qlogic firmware on 21.rc2 is 1.18. On 1.6.5 it is 1.27.
- I have a partial dump (DeclROM only) of 1.6.1, which is dated to 28-Apr-1995.
- Interestingly, the 1.6.5 firmware drives report their disk driver as "SiliconExpressIV Rev 1.6.5", while this copy of 1.6.1 reports "Avid Rev 1.6.1" so it may be a customized firmware for Avid setups.
- You can find an updated copy of the manual here: https://www.target-earth.net/wiki/lib/exe/fetch.php?media=blog:se-iv_manual_new.pdf
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