3 megabit ethernet

Haven't seen any since.... 1996?

It's getting AWFULLY close to the first of the month... but what the hell!

I haven't seen (Motorola) 10000 series ECL chips for sale in YEARS, but I honestly can't recall if they were used in the 3 MHz version or just

10Base5 reference implementations. Given we're talking 1976, I vaguely recall most of the circuit was discretes. Hey, at least it wasn't vacuum tubes.

Why? Sneaker-net would be faster to implement. (yes, I do have a box of 8" floppies as well as several boxes of 5.25s).

Old guy

No, it is actually for an Alto.

I think they don't have floppy drives on them.

-- glen

Never worked on one, but my understanding was that the chips used were "ordinary" 74 series TTL. The 74164 (S->P) and 74165 (P->S) were 8 bit parallel shift-registers. The line driver and receiver were discretes.

What are you actually trying to do?

Alto - correct, the hard disk cartridges were removable. I was thinking of the more "modern" DLion, which did have an 8 inch drive. We had a number of them, and at least one had both 10 and 3 MHz interfaces, which was used as a limited capability router.

Old guy

(snip, I wrote)

(snip)

Someone else is actually trying to do it, which is connect an Alto to modern ethernet. I believe the reason is to use it for network based disk storage.

One possibility would be to create a bridge between 3Mb and 10Mb ethernet. Another would be to adapt a 10Mb to the Alto I/O bus, such that it could talk to it like it was 3Mb. (Yes, I know that 3Mb has 8 bit addresses.)

Thanks.

-- glen

Didn't think there were any outside of museums

I'd assume you mean having an outside box act as a network disk for the Alto - the other way 'round makes no sense, as the Alto disks were something like two or three megabytes.

about the only solution

Never worked on the hardware, but my impression is that the interface was CPU bandwidth limited - and can't service interrupts much faster than the

3 Mb demanded.

The bridge device (actually a gateway) handles that.

Old guy

(snip, I wrote)

It is in a museum, but it is supposed to work.

Yes.

I don't know the details, but it seems that the disks don't work very well.

Well, it could also be a router. There probably won't be much else on the net, so it probably doesn't matter much either way.

That is fine. At some point, most devices couldn't handle interrupts as fast as 10Mb/s ethernet could generate them, but most of the time they didn't have to.

Yes.

I just put that in, in case someone thought about mentioning it.

-- glen