Description

Vintage SBC Netronics Research COSMAC Elf II - Restored/Tested/Working 

This is a vintage, single board computer, from the late 1970s. It was assembled from a kit sold by Netronics Research. It has been tested using a few programs and it seems to work as intended. It comes with a nice complement of documentation.

The Elf was built around an RCA 1802 microprocessor. The 1802 is an 8 bit microprocessor with a unique architecture and a unique instruction set. It was the first, low-power, CMOS-based microprocessor and this allowed it to run much cooler and by using much less power than most processors available at the time. The 1802 was used in industrial, military and automotive applications and it has even found its way into a couple of game consoles and pinball machines. The 1802 was also available in a radiation hardened version which was used on many space program projects. The 1802, being a CMOS microprocessor, has a unique feature which allows it to function at any frequency from one hertz up to its maximum rated frequency - this made it easy to single step programs for debugging without using any specialized hardware.  

This Elf was recently restored and tested. It is in excellent condition with no rust, no corrosion and no musty or cigarette smells. All chips are socketed. The white keypad keycaps have not yellowed much and it even includes the factory-original wooden triangular supports.

While restoring the unit, three chips were found to be defective and were replaced – they’re identified by a piece of green tape with a red dot on the pictures. The original replaced chips are also included. Also included are many brand new spare replacement chips and 7 segment displays.

This unit had a defective "Input" pushbutton (lower right pushbutton) which has been replaced. Unfortunately, I did not keep the original pushbutton.

Other than the replaced chips/switch mentioned above, everything on the board is original and period-correct. The 1802 CPU is a purple ceramic RCA chip and the PIXIE chip is the original RCA 1861/TA10171X. I've tested the video output by using the sample program listed in the assembly manual on a very old composite monitor. The monitor could not sync to the video signal (the image was wavy), however there was a valid video signal coming out of the ELF (as shown on the pictures). I do not have another composite monitor to test further. Note: the screen is supposed to display the word "COSMAC" and a rough image of the Star Trek Enterprise, however I only entered a few lines of the image data into memory resulting in only the very top portion of the star ship being displayed just underneath the word "COSMAC". 

A few programs were loaded from the keypad into memory for testing and all ran as expected. All keypad keys/toggle switches work as intended and the 7 segment displays are bright and clear and have no defective segments. The printed circuit board is in very good condition with no lifted traces and all traces are (factory) tinned.

Included with this lot are (1) the working Netronics COSMAC Elf II single board computer complete with the original triangular wooden supports, (2) a 120 VAC to 6.3 VAC power supply with on/off switch (on the low voltage side), (3) the original Netronics kit assembly manual, (4) the original Netronics schematics, (5) an original 1802 data sheet, (6) an original 1861 data sheet, (7) the User Manual for the CDP1802 COSMAC Microprocessor, (8) the RCA COSMAC Microprocessor Product Guide, (9) the COSMAC Microtutor II Manual, (10) the Binary Arithmetic Subroutines for RCA COSMAC Microprocessors manual, (11) the Operator Manual for the RCA COSMAC Development System, (12) photocopies of the original Popular Electronics ELF article (parts 1, 3 and 4 - part 2 is missing; however,  I’ll include PDF copies of the four Popular Electronics issues in which the articles appeared), (13) more than 20 brand new spare chips, (14) replacement 7 segment displays, and (15) the original (defective) chips  that were replaced. 

Note that not all included manuals are specific to the Netronics ELF, but may contain very useful complementary information on the 1802.

While the included printed material is in good overall condition, some of the documentation (especially (3), (4) and (12)) contains some handwriting, some underlining and some highlighting.

Here is a great opportunity to own a unique, rare, functioning, single board computer from the very early days of the microprocessor revolution! Despite this unit having been somewhat tested and shown to work, it IS over 40 years old technology and I cannot guarantee continued functioning. This lot is being sold as-is with no returns accepted.