Econet (Was: Re: 8-bitters and multi-whatever)

Quite likely. [...] It doesn't sound like collision detection, which used an analouge comparator chip (LM319 IIRC). The 4017 is a devide-by-10 ring counter, the '74 is, of course, a dual D-type flip-flop. It's either something to do with sorthing out bus timing (maybe early 6854s had some oddity here), or a way of sourcing the econect clock from that PCB. [...] This has the interesting side-effect that a Model A that's been upgraded to a Model B has rather more stuff in sockets than a Model B that started out as such. For example half of the RAM is socketed on the former machine. I still wonder if it was really worthwhile to miss out the 1MHz bus buffers on a Model A and fit sockets in place of them. I can't believe the latter were much cheaper than a '244 and '245 :-) Or was it because there were many passive components to solder in anyway? Did any of the other upgrads involve anything other than ICs? You should have asked when you visited me. I have a Filestore (whatever the origianl version with the '2MHz bus connector' on the back is called), I would have been happy to take the case off for you... One day I'll get round to getting it going. It's missing the floppy drives -- I have a couple that will work, but theyre ex-Archimedes machines and are therefore lacking ffront panels and eject buttons, and it's misisng the front flap, which of course triggers a reflective opto-switch. I am sure I can fiddle soemthing to do that, though. -tony