HP HP-2117F on ebay

Christian wrote.... I doubt that seriously. I'd like to see how you could put a FAB board in an I/O slot ;) On most 21MX/F's the general F-specific microcode was put on a FAB board which goes under the cpu board (as a daughtercard). The reason was simple - they didn't want to waste an I/O slot with a FEM. Another reason is because many systems had hard coded requirements of what boards you put in what I/O slots, and a FEM board messed things up. When the FAB board ran out of room then they'd start going to a FEM. When possible, I like to remove the FAB and only use the FEM as it's easier to get to the roms and change them (and I change them a lot). Most people would rather use the FAB as firmware was rarely changed and they valued the I/O slot real-estate. A wild guess - this system had vendor supplied proprietary microcode on the FEM that was in slot 10. When the system was decomissioned, the licensed firmware board (the whole FEM) was yanked. The F microcode is likely on the FAB underneath. More to the point... note that a FAB (and FEM) was optional on the E series. On the F series, the FAB was required but the FEM was optional. Why? See above. I wrote... Christian replied... Well, it sure could if you need a TBG and don't have one already. What if the cable was to generate interrupts to the host from an external device, and the setup was a 'normally closed' configuration? Your processor would become rather sluggish when interrupts were armed :D There is a reason I prefer these "simple boards". My preferred setup typically uses six 12566 boards per system. I find myself changing their configuration a lot. It's been a while, but I seem to recall I had to generally change the jumper settings any time I wanted to run diags on them too. The non-microcircuit badged 12566 boards (GRD TRU +/-) are all soldered jumpers, some of them 3 way posts with multiple jumpers. The microcircuit badged 12566 boards are generally the later revision that uses jumper plugs. MUCH easier to work with if you're changing jumpers a lot. I think the later revisions also offer some additional functionality that the older ones don't. Something about a "party line" seems to be lurking in foggy memory... Doh! I should have noticed that. The led & plugs on the left are a dead giveaway. But since that board requires DMA.... and there's nothing in slot 22.... That's not necessarily correct, the machine on ebay may WELL be an F series, and likely is. See that shielded ribbon connector on the back left? That's connecting the cpu to the FAB board underneath (as well as a dangling end for what was probably a FEM board in slot 10). So I bet ya a lunch that the F firmware is whats on the FAB underneath. Again, Im not an expert on the F series. But the 2111F doesn't have an external FP processor does it? Just the 2117F does? Both are certainly F series. I believe I have those... I think I just saw the DS1000 roms a few days ago on my workbench. Ya know, there's a problem with just using a FEM board. You don't have the sockets for the smaller proms there. Only on the FAB. Ah, that's why I wanted to find blanks for the larger proms - so I could migrate the IOP firmware to the FEM. WCS would be more fun.... Jay