Hi All, I've abandoned the Psion Organiser in favour of a PC with a USB-to-serial interface and a terminal program. Termite doesn't go slow enough so I've tried PuTTY and Realterm. I've used both with

For many years, I've thought it would be fun to do an 1802 calculator. It seems like the perfect chip for the job. Simple, low power, good I/O, enough registers to use without RAM, etc. I could have a

I was thinking about asking the list members this calculator question well before this present active thread began. Was looking to buy a used calc somewhat cheap on Ebay that could store at least one

For some time I've been seeing strange behaviour in Mar1e. Quite often a program would crash. I'd look through the contents of the lithium-backed RAM and it would have changed, but then it would chang

Wow! I can hardly believe it! It was too easy. I typed UT4 into an EPROM (via my Stag) a few days ago. I installed it in the second 24 pin socket. I decoded the addresses with a 139. I diode ORed the

While looking for something else, I found an old OLD article on a handwriting recognizer. No micro, no ICs, no transistors, not even any vacuum tubes. It was all done with relays! The technique was so

Hi All, No doubt many different cassette interfaces have been tried over the decades. Is there one particular recording format and circuit that's floated to the top and become most widely used? I want

Hi - I've been asked to make the full schematics for Todd's ELF-ish available, so I have. I've uploaded the PDFs to the new folder "Todd's ELF-ish Schematics", https://groups.io/g/cosmacelf/files/Todd

Hi 1800 fans - This week, I finished adding the CDP1851 Programmable I/O Interface and the CDP1878 Dual Counter-Timer to the VIS board. These have nothing to do with the Video Interface System, but th

I hardly dare post my humble efforts in the same forum as Todd's, but here goes... I've typed UT4 into a 2732 and wired Mar1e's second 24 pin socket for the EPROM. A 74HC139 selects the 6116 at 0000 a

The ELF-ish so far has 4k of RAM, partially decoded on the main board using a CDP1859 to decode the four 1k blocks, with the first 1k further decoded to four 256 byte pages. The CDP1859 !EN is enabled

The blank space to the left of the memory expansion boards in the 16k RAM version of the ELF-ish is just screaming out to be filled with something. So let's go for something big! But first, I was gett

Hi ELF fans - In August 1976, Popular Electronics magazine began a four part series of articles describing how to build a Microcomputer Trainer that could fit into a then hobbyist's budget, the COSMAC

Can anyone recommend a tool that is readily available today that can strip 30 awg wire wrap wire? I recently purchased via DigiKey a Jonard stripper with range of 20 to 30 awg. It doesn’t work on the

Hi ELF-ish fans! Now that the ELF-ish base build is finished and we have the first memory expansion board to bring the system up to 4k RAM, it's time to turn our attention to populating the upper half

Hi Todd, Here are my UART patches for IDIOT. UT4 should be similar. First, initialize the UART. 0000 ; 0075 ORG = #0000 .. RJ for Membersip Card 0000 71; 0076 RESET: DIS .. DISABLE INTERRUPTS 0001 00;

Hi could anybody help here? I just found out about IPS and the Amateur Satellites ( AMSAT) in the past. As the software was first implemented on an 1802 as of Rad-Hard, I wonder if anybody here was in

Hi Todd, This is all going to be immensely helpful to me as I expand my Elf called Mar1e. Thank you very much for sharing all your work with us. Mar1e is currently being rewired, with two DL1414 displ

Once upon a time, in a galaxy far far away (back in the 1970's, actually) I remember playing the old Star Trek game on my computer. It was a text-only game, where you explored a number of 8x8 "sectors

Hi - I'd like to use the PS/2 interface from the ELF2k in my own project, but need to tweak the AT89C2051 code a bit. Does anyone know what compile environment was used? I have the code from "Elf2K Fu