First EEVBlog Forums post: homebrew 1986 vintage GI SP0256A-AL2 Speech box - Page 1
Forum section: electronics / projects

author: spicyjack
author_rank: Unknown
timestamp: November 23, 2019, 04:07:12 am
content: Dave said that I had to post something with my shiny new EEVBlog Forums account, or my account will get purged during a spammer quell, so here goes.Sorry this post is a bit wordy, but I thought it was a good story. Admins/mods, feel free to move this to a different forum if I'm posting in the wrong place.My first computer was an Atari 400, and I used to have a subscription to A.N.A.L.O.G. magazine (a magazine for 8-Bit Ataris, and then later Atari ST's). I think the first issue I got was issue #10, in October of 1982. When A.N.A.L.O.G. issue #29 came out, there was an article inside called "Cheep Talk", which showed you how to connect a the General Instruments SP0256A-AL2 speech synthesizer chip up to the Atari so that you could play sounds out of a speaker. If you're familiar with the TI "Speak and Spell" edutoy/device, this chip generates a similar robotic "voice".Once I saw the "Cheep Talk" article in 1985, I knew I had to build one, and I managed to do it in 1986, say May/June of 1986. I ended up using this as a "final project" for an AP Computer Science class in high school, which saved my ass, because I spent more time that semester trying to play video games (Karateka and Ultima IV on school Apple ][e's) than doing computer science-y things (shout out to UCSD Pascal!)Below I've linked the original A.N.A.L.O.G. article hosted onhttp://archive.org, along with the OCR'ed version if you want to download the BASIC demo source (and fix the OCR mistakes).I was able to lay out and etch a bare copper board using the Archer stencil kit (which I still have) and the Archer acid etching kit, using the original schematic (image below) as a board layout guide.The computer that ran the BASIC/assembly language demo program during my AP CompSci final was the aforementioned Atari 400, which has 4 DB-9 joystick ports in the front. These joystick ports can also doOUTPUTas well as joystick input. If you wanted, you could change the demo 6502 assembly code to use ports 3 & 4, so you could leave ports 1 & 2 free (for games, of course). The GI SP0256A-AL2 board is powered off of the +5V from the joystick ports, and the external speaker had it's own battery. The demo speech output in the article is the start of Lincoln'sGettysburg Address, if I remember correctly; I had this and my own demo loaded up on my computer when I presented my final project in class.Yesterday I pulled this board out of the box where it's been hiding for the last 30+ so years so that I could take a few pictures of it and post it here as my first post. The velcro on the ribbon cables I added the day I shot these pictures, but otherwise, this board/box has been pretty much untouched since I put it away around 1990 or so. These pictures were taken with a new iPhone 11 Pro, if you're curious about those kinds of things.Things that I'm noticing 30+ years later that I didn't remember until I pulled it all apart for these photos:I stripped the threads of the plastic project box early on, you can see the white on three of the posts where I put live wet Elmer's Glue in the holes, then popped the screws in the wet glue, let it dry, and then like magick I got new screw threads in the plastic case...The scratches on the board around the solder joints are where I scraped off the flux with an Xacto knife. I didn't have flux cleaner, that cost moneyEverything on the Archer stencil kit sheets could be used on a board, as you can see on the etched board; I think the small letters below the year came from a different stencil kitThe board is laid out 90 degrees from the original; I just noticed that the chip is "horizontal" on my board (compared to the case), and the holes for the data cable are on the "side" of the board, instead of being at the top/bottom of the board like the original board layout image (below). I may have only had this piece of copper left, hence the altered layout...My dad worked for the local telco, he gave me a spool of phone hookup wire, like they'd use in a local junction box; this is what I used for wiring up the speaker jack (B & B/W)I still have the Archer speaker (RS # 277-1008) shown in the BOM in the article, but no pictures of it. It's starting to yellow on the face, and I should probably make sure there's not a battery in it.I'm extremely happy that I etched in the year into the copper, that helps me nowa lot. Yeah, "The Fly" is kind of juvenile now that I look at it, but oh well.There's a bodge job on one of the caps. I think I cut the leads too short, but I was able to fix it.Final thoughtsI'm still stoked that I have this board, and I do want to get it running at some point. I have no idea if it still works, but I don't see why it wouldn't. I do have a bunch of Atari 8-bit hardware (something like 3 Atari 800's, 2 Atari 800XLs, and a ton of other stuff), so it's within the realm of possibility to run it on the "original hardware" as it were.In addition to getting this board running, I was thinking about how to "modernize" it for people who don't have access to the original hardware; maybe using samples of the original audio and an ST or Atmel/Microchip ARM board of some kind... BLE/WiFi/blah blah, who knows.Thanks for getting this far, and if you have any questions, ask away, and I'll do my best to answer.LinksA.N.A.L.O.G. "Cheep Talk" article, hosted on archive.org:https://archive.org/details/analog-computing-magazine-29/page/n59OCR'ed version of the above article, if you want to scrape the source and run it:https://archive.org/details/analog-computing-magazine-29/page/n59