Netronics ELF II

[maynard]

First computer I built. Came with a PCB board, a 1802 and 1851 and some TTL chips. I bought extra sockets because I thought I might nuke a few soldering them in. Soldering the hex keypad on was the worst. I was twelve at the time.

It DID work. The thing taught me hand assembly. As in, writing mnemonics on paper and hand assembling to opcodes. Then keying it all in and seeing what happens. A big step up from writing BASIC on a trash-80. And really helped me transition to z-80 assembly. Which, I probably could have done without it. But I didn't believe I could. So the ELF trainer route it was.

A nifty project for a kid back in 1980. Does anyone here remember them? I know there are some 1802 fans still out there. And chip-8 still seems to be a thing (though I never used it back then).

 

[Moonferret]

Yup, I have one here on my project pile. I don't think it's working correctly at the moment although it does have the Giant board which provides a ROM monitor, serial, parallel and cassette interfaces. Great little machines for learning machine code and how early computers work.

Do you still have your machine? Did you expand it in any way?

Cheers,
Dave

 

[Chuck(G)]

The 1802 enjoyed a certain amount of popularity in the telemetry world, as it was one of the few MPUs available in CMOS and was capable of fully static operation, so could be slowed or stopped when not needed. Very important if you're running a data gathering operation at the end of a rope in 60 feet of water.

The other CMOS MPU of the same period that comes to mind is the Intersil 6100--but that requires a 12-bit wide memory, so perhaps not as popular.

The Netronics ELF was the follow-on to the original RCA COSMAC ELF.

 

[codeman]

That was the first computer I used also, my dad bought it and we assembled it then I sat and typed in the enterprise image and got it right the first time .
My dad used it for years running Forth . Some day i will get all his Forth stuff on the net .
ken

 

[maynard]

Yup, I have one here on my project pile. I don't think it's working correctly at the moment although it does have the Giant board which provides a ROM monitor, serial, parallel and cassette interfaces. Great little machines for learning machine code and how early computers work.

Do you still have your machine? Did you expand it in any way?

Cheers,
Dave

It's long gone, sadly. I built the Giant Board. And I built a 4K static RAM board. I set up a cassette tape drive (swiped from the family's TRS-80). And I had it connected to a little b/w TV. But for some reason I never hooked up a keyboard for Tiny BASIC. Instead I was playing with trying to hook up a fish tank thermostat to the thing's output ports to control it. And I never quite got that working right. And by 1982 my dad had bought a PC and I'd gotten the trash-80 with two disk drives as a hand-me-down. And then the ELF took a back seat.

 

[BillOldy]

The 1802 / COSMAC RetroComputing community is relatively large and thriving.

Most of these older machines are typical CRAV systems (Classic / Retro / Antique / Vintage).
And almost anything like that costs money anymore, especially if it is collected and collectable.
And collectors can get rabid, especially if there is a bidding war.

It is not easy to find older machines like that in good shape and good working order.

And the various chips are becoming increasingly difficult to find, as well.

Mostly these days you have to wait for random luck or for someone to die and have an estate sale.
(the latter happened recently) (and then hope you have money at the time)

There are some new(er) kits (Membership Card), and you can always build one from scratch
from the 1975 Popular Electronics magazine, and there are quite a few emulators and simulators, too.
And some home "game machine" consoles, like the RCA Studio II.
And some actual computer systems that are more than SBCs.

Links:

https://groups.yahoo.com/neo/groups/cosmacelf/conversations/messages

https://en.wikipedia.org/wiki/RCA_1802

http://www.MDCCCII.com/

http://www.donnelly-house.net/programming/cdp1802/simelf/

 

[DeltaDon]

Recently I dug out my Quest Super Elf along with it's S-100 expansion board. Somewhat worst for wear having been through several moves since the '80's. I also have a Netronics 64K Jaws memory board for it and an abused Netronics video terminal board too. I think I used a S-100 video board before going over to the terminal. Lots of 1802 documentation including some handed out by RCA when they introduced the 1802 to the engineering world. I have (had???) some Quest 1802 programs, including Tiny Basic, on cassettes somewhere too. One more project that needs to be looked at.....

 

[saundby]

I just got my Netronics Elf II back from a friend who borrowed it from me in 1980 and only got it back to me last Sunday. I'm overjoyed to have it back. It was in kinda rough shape when I got it, but I've got the core of the system functioning again with a few caveats. Perhaps someone can help me with some questions I've got since I haven't turned up my Elf II assembly instructions and other stuff yet (I know it's around here somewhere, I turned it up in the middle of a pile of project schematics about 8 years ago.)

The NSN373 display has one segment that isn't lighting. It flickers in and out again every so often. I haven't found a source of these displays, but I see traces on the board for what look like standard 7 segment displays. Does anyone know the specific displays that this will use, or know the pinout to save me figuring out the traces manually?

The Input key is an old-style Stackpole switch (like the rest of the keyboard on mine), but it's hors de combat. I opened it up to fix the spring contacts inside, which were bent out of shape, but it's still not connecting reliably which won't do for this switch. Does anyone know of a source of replacement switches, or even something that has the same PCB footprint that I can use?

Beyond that, I've got the 1861 putting out a signal that looks like video on my oscilloscope. Two composite monitors haven't shown any sign of an incoming signal, though, so I guess I need to check the clock frequency to make sure that it's still good after 40 years. Other than that, all I can think of is putting a video amp on the signal to see if that does the trick. I'll have to try monitoring the signal when I have it hooked to the monitor to see if it holds up when connected, so far I've only had the 'scope on it when the output was disconnected.

Below are pics of it as I got it back, and after some cleanup with keycaps removed. There's been more work since then (like getting an 1861 from my drawers and plugging it in. Thank goodness I bought out HFE Electronic's stock of 1800 series stuff before they closed a few years ago!)