Piecing together an HP9880

I am not sure if this is on-topic since the machine involved was sold as a calculaotr. On the other hand, it programs in BASIC, it's getting on for 40 yuears old, and I am thinking of adding a hard disk. Classic computer? The HP9880 is the hard disk (14" platters) for the HP9830 'calculator'. I am slowly gathering the various bits of this system, I would love to get it all working again. As I understnad it, you need : An HP9830 calculator, HP9866 printer Mass Memory ROM module HP11273B 'cable' from the HP9830 to the controller HP11305 disk controller HP11302 cable from the controlelr to the drive HP7900A disk drive (one fixed, oen removeable plater) + PSU (or HP7901, which has only the removeable platter, but has an internal PSU) System tape cassette for the HP9830 Disk packs (of course). Now, The 9830 and 9866 I have, working. The HP11305 controller and both 'cables' (I put that in quotes becase thes cable assembleis have PSBs stuffed with ICs at at elast one end -- the 11273 has over 50 ICs in it) I also have, untested, but I know th PSU is good and the microcde ROMs look OPK (the disassebmyl of the mcirocode makes sense). Since everything else is standard TTL, analogue or RAMs ICs, I think that's reparaiable if necessary. I have the scheamtics and micorocde source for all that. The HP9800e emulator includes a dumo of the Mass Memory ROM, and thus I have it in an EPROM module. That emualtor also has an image of the ssytem and service tapes for the 9880, but as yet I haven'tt figured out the format of the image file or how to get them back onto physicl cassettes. I do have another tape drive mechansim (not HP) which sould be able to produce compatible tapes 'Just' a little matter of figuring out how ot interface it to soemthign and use it. At least I ahve the handbook for said drive, it includes timeing diagrams and schematics. Which leaves the drive and packs. This is the problem, I susepct I do havev a 7900A. Alas it was in a skip (dumpster) and had a 2100A thrown on top of it. The 2100A survived. THe 7900A is more sdubious. The front was samaged when it was gtaken out of the rack too. It's missing the terminator and the little card edge conenctor PCB, but those are easy to make I think. It's going ot need work. I also don't have the PSU for it. This seems ot be 120C AC (not isolated from the mains) for the blower and spindle motros), unregualted +/-24V and regulated +5V, +/-12V. Nothing difficult, but I can see myself speding time and moeny making something and then find the heads will no logner fly. I susepct replacement heads are not exactly common, I wonder if RK05 heads can me made ot fit? According to the HP nanual for the drive, there was a text/service unti for this drive, it conencted ot the side of the backplane. I cna't rememebr the model numebr (HP13219?). Hase anyone ever seen one, or have the manuals for it? And now for the pack. It's the same physicla size as the RK05 pack, but 24 (hard) sectors. Of coruse there's the fixed platter in the 7900A drive with it's own 24 sector hard dsetoy rign nad transducer. I belived the drive will spin up with any pack in it, so I could put a 'scratch' 12 sector RK05 in there to (a) see if the heads will fly and (b) see if I can use the fixed paltter (which will be 24 sector) drom the HP9830. If I get that far, I guess I then take an RK05 pack apart and attempt to put anotehr 12 notches i nthe sector ring. I beleive I then have to re-centre the platter on the hub which will be 'interesting' What if the heads crash? Maybe try to fit RK05 heads (I have some brand new spares here). Maybe try to interface an RK03 or RK05 to the HP contorller. The interface is differnet, but at least the data rate is the same. It woudl take a bit of logic to get it to work, but... If all else fails, make a solid-state repalcement for the drive? I gueess the questions at the momnet are : Anyone know the precise details of the tape image file format for 9800e? Anyone ever manage to fit RK05 heads into an HP7900? Anyone ever managed to cut the ectra sector notches? Anything knwon about the disk service unit for the HP7900? Does anyone have any comments/thoughts. Am I totally crazy for trying to do this? -tony