8" floppy project

For the very simple reason that the Teledisk archive format is undocumented, which means the only thing that can read/write it reliably is Teledisk itself. Which means that you can't use the Teledisk format as a universal archive format (which is what we are discussing here), since you couldn't, say, write a program that used the Catweasel to read an Apple ][ disk and store the result in a Teledisk-structured file. Let me give a real example of when this could be useful. Suppose you have a PDP11 running RT11 with 8" floppies. Now, DEC made 2 types of 8" floppy unit, the RX01 which used an industry-stnadard FM (single-density) format and the RX02 which used a very strange DEC-specific format. To make life more interesting, the classic-PERQs have a floppy format called 'Interchange Format' which is very similar to the RT11 filesystem. Similar enough that a PERQ can read/write a DEC RT11 disk, and a PDP11 running RT11 will read/write(with one minor problem) a PERQ interchange disk (the difference, for those who are interested, is that the PERQ interchange disk has one extra word in the directory entry of each file which is used to provide a true file length value, not just the number of ;blocks used). The PERQ hardware uses an NEC 765 controller (same as a PC) with a data separator capable of working in FM (single density) or MFM (double density) operation. The single density is compartible wiht the DEC RX01, the double density is, of course, incompatible with the RX02. But any PC controller capable of high density operation can read the double denisty PERQ disks, and PC controllers capable of single density operation can read the single diensity PERQ disks and DEC RX01s. Now remember that the file system is essentially the same on all these disks. It is possble to design an interface to link a DEC RX02 up to a PC (the interfave to the PDP11 bus is quite simple, doing it to ISA wouldn't be much worse). In which case you could read these strange DEC not-quite-double-density disks on a PC. But what you couldn't than do is create a Teeldisk archive of an RX02 becuase the format of that archive isn't documented. And suppose you want to do more with the disk images than just write them back to disk. Maybe use them with an emulator on the PC. Maybe extract files from them. Since the format of the Teledisk archive isn't documented you probably couldn't do this. And even if the limited docuemtnation that exists is enough, you would have to write 2 programs (or add all sorts of conditionals to one program) -- one to handle RX01s and PERQ double-density disks saves in Teledisk format, one to handle RX02s archived in some other format. No thanks. The whole point of a universal archive format is to only have to do this sort of thing once. So do I, I am using it right now. However in my experience that more complex the chip, the more likely it is to fail (this doesn't mean that the overall system reliabity goes down -- it doesn't because there are fewer components to fail in a more modern machine with high levels of integration). But I would suspect the 74xx chips on my PC's motherboard will last longer than the gate arrays in a modern machine. You nave been _very lucky_ OK, trivial... If you want both hardware and software documentation (i.e. schematics _and ROM source code_) then the obvious ones are : Apple : Apple ][ and Apple //e (and maybe other machines in that family). I am told the IBM PC Techref was modelled on the Apple manuals. HP : HP71B. I am sure you've read the complete IDS (I certainly have, it's excellent). Incidentally, do you have the HP71 Forth IMS (Internal Maintenance Specification)? It's very interesting. Research Machines : RML380Z. It's a separate hardware 'Information File' giving schematics, etc and a COS (Cassette Operating System) Source listing. Admittedly I've never seen the latter (it was an optional purchase), but it existed. DEC : PDP11. The PDP11/45 CPU technical manual and printset (schematics) are much better than the IBM Techref. You could get a source license for the OS if you could afford it, too. DEC : PDP8. I am not sure about the OS sources, but the hardware manuals, at least for the 8/e are again excellent. HEath/Zentih : H89/Z90. The manuals I got with my Z90 had schematics and ROM source listings in them. If you just want hardware docs (i.e. full schematics) and the programming interface (i.e. not full ROM sources) then also : HP : Portable+ , HP150, etc (and I assume the HP110). There are excellent technical manuals for these machines Acorn : BBC Micro, Archimedes, etc. Again, schematics are easy to obtain either in 'Advanced User Guides' or service manuals Raido Shack : All TRS-80s had service manuals available to anyone who wanted to order them. And many had technical reference manuals available as well. Need I go on? IBM service manuals (at least the Hardware Maintenance and Service manual i have for my PC/AT) are boardswapper guides. They're pretty useless now, they are totally useless when there are no more boards to swap. This has nothing to do with being able to maintain the machine. And most of those books are not worth the paper they're printed on! And do any of said classes actually cover the hardware at the chip level? Firstly the PC wasn't built entirely from TTL. There are some standard Intel chips (CPU, DMA controller, interrupt controller, etc). And of course programemd ROMs. If we allow those, then a partial list would be Apple ][, TRS80 Model 1, Model 3, Model 4, Sinclair ZX80, Nascom, HH Tiger, TRS-80 CoCo 1, Dragon 32, Sage 2, Apricot, Sirius, etc, etc, etc If you allow PALs, then you could even add the early Apple Macs to that list, along with the PERQ 3a, Torch XXX, etc If you want to move the goalposts and not allow LSI processors, then how about PDP8/e, PDP11/10, PDP11/34, PDP11/45, (etc), Philps P850, Philips P854. PERQs (all except for the 3a, although admittedly there are LSI chips -- but not custom ones -- things like a Z80, NEC 765, etc -- on the I/O card), HP9810/20/30, and many, many, more. Correct... Fine... You use a PC, that's yuor choice. However, I am not so arrogant as to want to impose my choices on the rest of the world. In other words, the whole point of a universal archive format (let's not forget what this thread is really about) is that you don't have to use a particular machine. If you want to use a PC, fine, use a PC. You can write software to create and process that archive format. If I want to use a PERQ, well, I expect to have to write the software myself, but I can still do it. If Sellam wants to use his Apple ][ (and can therefore read disks that neither the PC or the PERQ can read) then he can do that. Actually, I was under the impression that the programming interface was docuemtned!. I may not care to use the card due to lack of hardware info, but that is not the same as saying that the card shouldn't be used, and that any archiver format I come up with will delibrately exclude the Catweasel. -tony