Well everything is now working! In total I made four (big) mistakes: 1. Used the wrong type of switch for IN. 2. Didn’t use IC sockets (because hubris / impatience / I’m a HERO) and either broke

FWIW, all the files for the STG1861 are in the STG Elf2K files area of this group... Bob

The design I'm building id Chuck Yakym's Rev E, not the STG design. Since Chuck Yakym's file area on the Group is under construction I've attached the files. The REV E is the video board, The autorun

The STG 1861 page is here: http://www.sparetimegizmos.com/Hardware/Elf2K_Accessories.htm#STG1681%20Pixie%20Graphics%20Replacement Mark, W8BIT

 Hi Bernie, That is the Intersil symbol on the top - not Harris. David Williams

Curious...any link where Chuck’s 1861 replacement circuit might be. Thanks

Hi all, I'm planning to build Chuck Yakym's 1861 replacement circuit and would like to hear the Group's experience and advice. Would using 74HC rather than LS logic work? I would like to use a

Hi Gaston, It is good. If you use the ESP-32 as a front panel, everyone will enjoy it with a web browser. I will try it when the project I am working on is over. Thanks, Kazu

Thanks so much Josh! Secretly I love it when things don’t work, as that is when I learn how they are supposed to work! I’ve checked all those pins, and so it seems possible that the RAM chip is to

John, Have a look at U2, with pin 7 so close to pin 8 ground... could there be a short there?

Hi John, Sorry, I made a mistake. I looked at the data sheet and tested my ELF, indeed, TPB and MRD pulse as normal during LOAD mode. LOAD mode just forces the CPU to continuously execute an IDLE

Matt wrote: Congratulations! You found it! Finding a bug like that can really make your day. :-) There needs to be something kind of prize for technicians that solve particularly nasty problems. How

All three of my extra board sets have been spoken for. Thank you! --- P. Todd Decker 913-284-8814

I have ordered a set of five of each of the RC1802 boards (processor, UI, and backplane). I only need two. So, if you're in the U.S. and want a set once they arrive, just private message me and I'll

 Thanks Josh! As I puzzle over it, some data: MRD - low until LOAD is up, IN pressed then pulses and doesn’t stop until LOAD is down LOAD_N2 - follows LOAD switch TPB - pulses when LOAD is

I need help confirming that an 1802 chip is a fake. The eBay seller claims the chip is using a new “Harris” logo. The date code on the back may be RCA? Looks fake to me. Comments please.

Hi John, You are correct, the LED should not follow the switches until you press the IN button. Verify STROBE isn't shorted low anywhere and scope the signals around U4C. STROBE should only pulse

> A desktop x-ray machine would be nice to have, I can imagine looking at a lot of things. Yes, I've just started to use it, I bought a Faxitron MX-20 last year on eBay. It has a fantastic Hamamatsu

Hello everyone! I’m new to the group, as I’ve only recently tried to get a 1802 Elf system working. I am using the RC1802 Revision F boards from https://github.com/tebl/RC1802-Cosmac-ELF I’m

After it was all said and done, it wasn't my FTDI cables. When I cut the U2/U8 traces, I nicked a via just enough to cause interference. One jumper wire later, and things were talking on the serial