Forum Rules and Etiquette

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This forum is part of our mission to promote the preservation of vintage computers through education and outreach. (In real life we also run events and have a museum.) We encourage you to join us, participate, share your knowledge, and enjoy.

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    Does anyone else have one of these Morse-Baudot S-100 boards by Curtis Electro? It looks like basically a fancy UART with onboard ROMs to presumably handle ASCII to Morse conversion. I'm interested to learn how it operates, would it take an audio input from a HAM radio via the RCA jack and decode the dots and dashes? There's also an empty DIP socket in the upper left, perhaps a connection to some other peripheral. I don't know HAM radio, so wondering if someone else can take a more educated guess.

    The big chip on the board is an AY-5-1013a


    Not sure at this stage in computing any one was good at converting received morse to dots and dashes on screen. The trouble is that certaining when this card was built a lot of morse was hand sent so there is a lot of variability in for example the lengths of the dots and dashs, which computer programs find hard to work with. Do I have that right? There are 8k of code on there? I think you need a manual

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals.


      FWIW, Jack Curtis passed away last year at age 87. He was known mostly for his keyer devices.
      Reach me: vcfblackhole _at_ protonmail dot com.


        Looking at the back of the board, the empty socket may have had an op-amp. It looks to have unusual power pins. I suspect they are +/- 15V.


          Using an IMSAI with the Cromemco 8K bytesaver (I knew it would come in handy some day) I was able to dump the contents of the ROMs into a HEX file capture on my laptop terminal and from there convert it to a 7K binary. The address switches on the Morse-Baudot board were set to A0, presumably that's where the ROM code would start. It should be Intel 8080 code.

          It is a curious question how this thing would work if decoding human generated Morse code, perhaps it was only meant to receive from another Morse-Baudot board, that way one could expect a fixed rate of transmission.ROMs.txt


            There were (and are) programs that decode hand sent morse. Basically you use heuristics to work out if its a dot, dash and if the space is an inter-element space. This paper (behind a pay wall) dates from 1959 so folks have been looking at it for a while...


            have a google...

            Looking for Analog Computers, Drum Plotters, and Graphics Terminals.


              Originally posted by new_castle_j View Post
              I was able to dump the contents of the ROMs into a HEX file capture on my laptop terminal and from there convert it to a 7K binary. [ATTACH]55721[/ATTACH]
              Just a question about the file as the whole Rom thing worries me in terms of data retention and I'm fairly new to programming and using Roms. In that file, towards the end, there are some broad zones where a number of the byte values have gone to (or were originally FF). Is that the sort of appearance one gets in a Rom file when there is Rom rot ? Or would it look different ? I noticed that there were no light occlusive covers over the Rom windows, so they might have been more at risk of it ?


                Sometimes (and you find this in a lot of early code), routines need to be at fixed locations, so the intervening unused spaces simply aren't programmed.
                Reach me: vcfblackhole _at_ protonmail dot com.


                  I believe 2708s erase to 0FF so 0 is ok.


                    Originally posted by Chuck(G) View Post
                    Sometimes (and you find this in a lot of early code), routines need to be at fixed locations, so the intervening unused spaces simply aren't programmed.
                    So you are saying that the sort of appearance seen there in that file with the zones of FF's you would judge as probably original programming ?


                      According to the attached article, the ROM software on this board was developed on an ALTAIR with a Tarbell cassette system, an ASR-33 Teletype and some SOL-20 boards and utilities. Oh, and a Cromemco Bytesaver! Examining the HEX, there's some oddball sections like this one:


                      Stuff like that is likely garbage that was left over in RAM when the code was burned into ROM. There's probably a bunch of other garbage scattered throughout the ROM image as well. After reading the manual on how ROMs were written from an Altair front panel and a Bytesaver board, it makes perfect sense. You would get your code running in RAM, then copy that RAM into the ROM, it would include all the artifacts that were left in RAM at the time.



                        There were also editor/assemblers that were completely RAM resident (e.g. Processor Technology) along with the source files. I used one on my Altair. Worked pretty well for what it was. That's likely where the source code comes from--the editor was one that used a BASIC-type line numbering system.
                        Reach me: vcfblackhole _at_ protonmail dot com.


                          Originally posted by Hugo Holden View Post
                          So you are saying that the sort of appearance seen there in that file with the zones of FF's you would judge as probably original programming ?
                          Some would intentionally fill with 0's. Others would leave these areas blank. Some would even fill with whatever garbage was in the unspecified RAM at that time. I know that the programmer for Heathkit was religious as he'd put something related in the empty locations. Most programs that used a checksum byte at the end of a ROM image would pad with 0's. My point was that erased by age would float to 0FFh rather than 00.


                            The only way to really be certain is to dump the PROMs and disassemble them to see if the code makes any sort of sense.

                            My money's on the 0ffh areas simply being unprogrammed. I imagine that the PROM programmer source was in the form of Intel .HEX files, which need not present contiguous data--there can be gaps and it's considered to be perfectly normal. A smart EPROM programmer would ensure that unused areas remained ff's.
                            Reach me: vcfblackhole _at_ protonmail dot com.


                              I have seen this board listed on eBay during the summer (several months).

                              From the 1970s to mid-1980s there were a variety of Morse/Bardot products (discrete & IC designs),
                              before the usage of Digital Signal Processors (DSP) in late 1980s (Texas Instruments & Motorola chips).

                              Since the FCC did not permit the usage of ASCII during the 1970s, the majority of the products
                              decoded Continuous Wave (CW)/Morse Code and 5-bit Baudot / Radio Teletype (RTTY). This changed by 1984 (AT&T Break-up).

                              The more advanced amateur radio products used keyboard (computer’s or dedicated)
                              to encode for transmission (Audio Output & Push-To-Talk)
                              Curtis Electro Devices was founded by Jack Curtis, K6KU (sk, 2018 ).
                              Jack designed “purpose built” ICs at Signetics (his 8044 series) in 1970s.
                              This specific board was very expensive, and not often seen.

                              The RCA Jack should connect to Audio Output of a Shortwave Receiver,
                              THEN tune the radio to a CW (Morse) or Bardot (RTTY) transmission.

                              In mid-1960s Bill Henry (Illinois BSEE) founded HAL Communications in Urbana, IL (before A. Clarke/S. Kubrick “2001”)
                              and had a number of dedicated RTTY and CW products throughout same period (1970-1990s).
                              Bill retired in 2012 ... but is still with us.
                              Last edited by w9gb; September 3, 2019, 04:57 PM.