Hidden away on one of the support diskettes, IBM has a small program named SCSILEVL.COM. It reports the microcode firmware version on most of the different IBM SCSI controllers used on microchannel (MCA) PS/2s (This page does not cover the SCSI RAID controllers that IBM had on it's server models nor the re-branded Future Domain controller IBM called the Patriot). Besides being a little too simplistic for my tastes, the program doesn't work on a few IBM models (Industrial Gearbox 800 & 8556/8557 & 9556/9557 PS/2s) that have SCSI implemented on the system planar.

I intend to expand the program somewhat, as well as document how it works. Most of the code is fairly easy to understand for those fluent in Assembler. For some sections you may have to see a debugging program (like Microsoft's CodeView for DOS) single-step through the code on a system with IBM SCSI. I recommend running the programs only in a pure DOS environment!

The original SCSILEVL.COM program doesn't even check if it is running on a MCA system (the things IBM takes for granted)! I just find some areas worth improving, mainly to make it check all the IBM SCSI microcode versions. The interface can also be changed to be more grammatically correct (i.e. not identifying a planar SCSI controller as being on a "slot").

IBM made three different families of non-RAID microchannel SCSI controllers, mainly distinguished by the microcontroller or microprocessor of the circuit that controlled the SCSI bus. Even though some of the controllers could use the same microcode firmware, I have separated them by how I see those series laid out. The functionality among the families is largely the same, with the members having similiar capabilities.

I don't profess to know what the different microcode versions added or fixed, but it is helpful to know if there is a later version for an upgrade (I will have some microcode images of the non-Flash series up soon so you can burn your own EPROMs if you have the equipment). Generally it is advised to have the latest firmware possible. I have charted all the versions I have found so far. If you have an unlisted version or one marked as unknown, please notify me to add it.