Archive for the ‘A2 Proto Board’ Category

End of an Era for Me

Saturday, December 17th, 2016

As look back at some of the blog postings I made during the early days of the Mimeo project, the excitement I felt, could be easily discerned. For better or worse, after nearly 7 years, that excitement is no longer there, and it’s time to move the project over to someone who has a strong passion for that landmark system.

I’ve transitioned Mimeo 1 sales to Corey Cohen. I’m sure he will do a great job selling and supporting people interested in building reproduction Apple 1 Computers.

Since first making them available in March of 2010, I’ve sold 167 Mimeo PCBs, the first few as part of a kit, even a few that were completely assembled and tested. I have greatly enjoyed the entire process from creating the PCBs in the first place, to fixing a few boards that customers needed help with. Especially gratifying, has been the great relationship that I have established with all the people that I have made contact with over the years. One thing that I never expected, when starting this project, was the amazing contacts I made with so many people associated with Apple during those early years.

However, the learning part of the process, which is one of things that keeps me interested in my hobbies, has not been there over the past few years. It is time to move the sales over to Corey, who has unbelievable enthusiasm and knowledge for and about those milestone computers.


I will continue to sell SCELBI PCBs, as I am still excited about working on that system and learning a lot, while doing it. Blog followers will know that the Oscilloscope Interface PCBs, the last SCELBI boards that need to be reproduced, will soon become available to interested parties. I have some ideas for some even more obscure reproduction vintage computer projects. However, the Oscilloscope interface must be completed, before I move on to those projects.

Other Products

Other products I have sold in the past, will only be continue to be sold if I have remaining inventory in stock.

I presently have stock of the following

  • Brain Boards
  • Swift Cards
  • I am sold out of the following:

  • Apple II, rev 0 boards
  • SuperProto boards
  • PS/2 keyboard adapters.
  • Datanetics Keyboard PCB
  • The PS/2 Keyboard Adapter

    The PS/2 keyboard adapter is a little bit of a special item to me. When I had those PCBs made, because of economies of scale, I had 150 fabricated. I never thought I’d sell all of them. In the end, I sold over 140 those little dongles, using the others for a number of my own special projects. Though they probably exist, I have never heard of a PS/2 keyboard that it didn’t work with. It was designed to operate with Apple 1 and Apple II computers. As I originally hoped, people adapted the design to a number of systems beyond that. The firmware has had minor firmware features and improvements made over the years, but the basic design hasn’t changed over all these years.

    There have been a number of other PS/2 keyboard to parallel ASCII keyboard adapters designed over the years, some coming before, and inspiring my adapter. Though it could certainly be improved further, I sincerely believe my version is currently the best of the breed.

    When I get the time to add them to my web site, I will be releasing to the public domain, with no restrictions, all design files, including firmware and PCB CAD files. You will be able to do what you want with it, make copies for sale, improve it, or just study the design for your own purposes.

    Kit and PCB status update and a question

    Saturday, February 1st, 2014
  • Coming for VCF east – SWYFT card reproduction kits – special introductory price if you join my SWYFT Card soldering Workshop – $40, drop me an email to register. Part of the proceeds goes to help support MARCH. After VCF east, price goes to $50.
  • Mimeo’s – out of stock – expect to have new batch around end of February
  • Datanetics PCBs – 1 left – rerun timing TBD
  • Brain Boards – 9 left – Note that I’m going to try move the remaining Brain Board kits over the next few months. I might even list them on ebay, to clear them out. If you want one, time to get it, is now. A rerun is not likely to be in the “cards”. I have a vague idea for an enhanced firmware board that may or may not get traction someday in the future.
  • SUPERPROTO kits – 8 left – rerun TBD – these are slow sellers and I haven’t actually made any money on these. However, I find them useful for my own purposes, so I might do another run (someday).
  • ACI kits – plentiful (currently I’m running low on PROMs, but expect I’ll be able to find another batch without too much trouble)
  • PS/2 keyboard adapter kits – plentiful
  • A2 rev 0 – ample supply
  • SCELBI 8H – I have less than 10 8H board sets remaining. I’ll make extra SRAM PCBs, when needed. Front Panels are in limited supply (less than 15, I think). TTY boards are plentiful
  • Now for the question – should I call my Apple II rev 0 reproductions Mimeo IIs, even though they came first?

    Initial SUPERPROTO to Swyft Card Conversion Instructions Posted

    Monday, September 2nd, 2013

    For those of you without soldering/rework skills, depending upon interest, I may do a run of reproductions, but it’s not going to happen for quite a while as I have too many projects already in the works.

    I’ll try to find time to do a video blog of a Swyft card in operation, but don’t know when I’ll find time, might be today, might be three months from now.

    SUPERPROTO converted into Jeff Raskin’s Apple IIe Swyft Card

    Tuesday, August 27th, 2013

    I just finished turning one of my SUPERPROTO prototyping cards into a Swyft card. If you don’t know what a Swyft card is, Jeff Raskin was working on a low cost “appliance” computer called the Macintosh at Apple. Steve Jobs took over the project and moved the project in a quite different direction. Jeff left Apple and founded a company called “Information Appliance”. The first product was the Swyft card that plugged into an Apple IIe and ran his software. The software was an integrated word processor and calculator, which had access to Applesoft and included a few other printing and communications capabilities. Later they came out with the Swyft computer which was later licensed to Canon – which called it the Canon Cat. I didn’t explore functionality that much, but the software looks pretty clever, despite the lack of a GUI. 🙂

    Once I get the rework instructions up on my SUPERPROTO Wiki, I’ll offer SUPERPROTO swyft card kits, with the components necessary to build your own SWYFT card, including preprogrammed GAL and EEPROM at the usual SUPERPROTO price of $65. The conversion of a SUPERPROTO to SWYFT card does require good soldering/rework skills, as you have to cut some traces and solder a few wires directly to pins on the back of the card. If there is enough interest, I could possibly make dedicated reproduction swyft cards.



    By the way, this was another one of those projects, where I didn’t have to buy a single part, everything needed was on hand, either part of an existing kit or in my spares bins.

    Kit and PCB availability Status

    Monday, August 26th, 2013

    Here is a summary of status of kits and PCB availability

  • Mimeo 1 PCBs – out of stock – new PCBs coming late fall 2013
  • Mimeo cassette interface kits – plenty in stock
  • Datanetics PCBs – less than 10 left – no brackets available – considering run of reproduction keycaps
  • PS/2 keyboard adapters – plenty in stock
  • Apple II rev 0 reproduction – out of stock – new PCBs coming fall 2013
  • Brain Board kits – less than 10 left – rerun plans are up in the air
  • SUPERPROTO PCBs and kits – less than 10 left – rerun questionable
  • SCELBI 8H PCB set – in stock – extra SRAM boards available, too
  • SCELBI TTY PCB – plenty in stock – still untested- caveat emptor
  • SCELBI front panels – probable Sept, 2013 – being anodized now, screen printing legend will be next
  • SCELBI 8B PCB set – layout work in progress – given the other ongoing projects, and other planned expenses, I’m realistically looking at 2014.
  • email: if you have any questions

    SCELBI TTY and Apple II Serial Card Update

    Friday, June 21st, 2013

    I now have SCELBI TTY cards in stock and will ship one to you for $30, shipping included. If you are interested send an email to: Be aware that at this point they are not tested, so until I get one tested, I don’t guarantee that they will work without modification.

    Regarding TTY card testing, I have been delayed because I didn’t have a current loop interface to test it against. Well that has been rectified, as I have the Apple II Serial Card that I mentioned in another post working (at least in RS232 mode). In order to get that card working in a way that would work for interfacing to the SCELBI TTY card, I had to reconstruct and burn a P9 PROM that matched the first version PROM. Wendell Sander was nice enough to send me a PROM that was a copy of his serial card P9 PROM. However, his P9 PROM was overwritten in a couple of spots with a all ones pattern. I took his PROM and compared the parts that were intact with the listing at the back of the manual and determined that I could resurrect his PROM by filling in the missing code with the code from the listing in the manual. After messing up my first attempt, I burned what I thought was a good P9 PROM. I put it in the Serial card and tested in RS232 mode against a Super Serial card in another Apple II. That simple test was successful and I now have a working Apple II Serial card without the undesirable flow control behaviors of the second version PROM.

    I should be able to use this card in current loop mode for testing the SCELBI TTY card. In fact, I have visions of putting it in an APPPLE IIe (for the needed 72 column support) and emulating TTY operation as closely as I can with the Apple II. I should be able to emulate not only print and typing functions, but emulate paper tape as well. Potentially, I could even add a real paper tape reader and possibly punch by constucting an interface on a SUPERPROTO board.

    As far as my prototype TTY card itself, it is mostly built up, just missing a couple of resistors which should arrive today or tomorrow. Once it’s together and tested I’ll put up a Bill of Materials, some simple build instructions and photos.

    Apple II Serial Card Initialization Details

    Saturday, June 1st, 2013

    While looking for a way to test the SCELBI current loop interface, I discovered that an early Apple II peripheral card, the Serial Interface Card, supported current loop. This card was designed to interface to printers and supported half duplex baud rates up to 19200 baud. Since I only need 2400 baud for SCELBI and the SCELBI only supports half duplex, I thought that I could use it for testing the SCELBI TTY interface card.

    I found that I had a serial interface card in my stash and tried it out, using the RS232 mode to see if it would work. However I found that it would only output 1 byte and then hang. I had a friend who scanned the manual for me and sent a PDF to me. Looking over the manual at first, I couldn’t determine what was wrong. However dumping the firmware revealed that the firmware was different than that listed in the manual. After some web searches, I determined that there was a second version of the firmware that supported RTS/ACK software handshaking and that this second version did not work with some printers.

    Since I couldn’t find a copy of the second version’s manual, this started me off on an reverse engineering investigation. This was a more difficult process than I first anticipated. Along the way I learned about some clever 6502 programming tricks, including a way to implement a primative 6502 skip instruction. I also have come up with a partly annotated listing that may be of interest to Apple II peripheral interface designers. This doc details some of the tricks involved in initializing Apple II interface cards. As the input and output functions are not of much interest, they are not well documented.
    Apple Serial Interface Firmware

    By the way, with the second version of firmware, there is no way to disable the RTS/ACK software handshake, so I’m going to have to find or make a copy of the first version firmware to test my SCELBI current loop interface.

    Say Hi At VCFse in the Atlanta Area

    Monday, March 18th, 2013

    This year, for the third year in a row, I’ll be leaving the family in the care of our dog, Toby, and be spending a weekend with fellow retro-computer hobbyists. Since this years VCFeast, had to be cancelled, I’ll be treking down to VCF southeast in Atlanta for the weekend of April 20 and 21st. These weekends are always fun, so I highly encourage everyone that might be interested in these things to make the effort to join us.

    Here is the link with informaiton for that event.

    Stop by my exhibit. I’ll be operating a Mimeo 1 and a reproduction SCELBI 8H (one of a very few working SCELBIs in the world). I’ll even give you a chance to “drive”. Tell me you read my blog and get a free SCELBI/8008 reference card.

    See you there…

    Beginning of Year Retro Update

    Tuesday, January 1st, 2013


    Last weekend, I sold the last of the Mimeo PCBs (Glossy and Matte) that I had in stock. I will make some more matte after I’ve sold some of the first batch of the SCELBIs. I’m down to 4 ACI cards, so I’ll have to do a batch in matte to go with the next batch of Mimeos.

    The new movie, “jOBS” will premiere at the Sundance Film festival this month. I’m hoping that the Mimeo PCBs that I sold to the prop house supporting the film, get some screen time and the film is good enough to get some decent reviews.

    I still have plans to do a full built up system, but that project will have to wait until I have the SCELBI going. I am sorry that this has been teaser for some folks who have been waiting for it. However, I’m hoping that when I finally get to it, that folks will be impressed with the results, and say that the wait was worth it.

    The new run of Datanetics PCBs have been trickling out, maybe a little faster than I expected, given the difficulty of finding components. They have mostly been combined with Mimeo PCB sales. I really wonder how many will get built up. This datanetics PCB batch has been done more of a service to the retro community, as it will be a while before this project breaks even financially.


    Quotes from Advanced Circuits on SCELBI boards are about half of what I expected, which is awesome. Nashua Circuits came in as expected, so I guess Advanced will get this business, unless Nashua can do much better (I’ll give them a chance to improve their quotes). Since there is no solder mask, it really shouldn’t make much of a difference who makes them.

    Design checks on the base 5 board set is done, and I’m about ready to declare victory on the layout tweaking/matching. The 8H backplane is just about ready, so I’ll probably get a batch of those made to go with the base 5 board 8H set, making it a 6 board set. The backplane has been challenging, as there is no schematic, only a wire list intended for wiring your own chassis. Good images of the top of backplane are non-existant. My orders for the PCBs may go in, as early as this week.

    I do have one thing to check on the CPU board. There were at least two versions of the CPU board made, I am replicating a later version. There is a report of an issue with the step function reported SCELBI digest, issue II. Though describing a problem in a later version of the CPU board, this report shows a slightly different design than the one in the version of the schematics/layout that I am replicating. I just need to make sure the schematics that I’ve followed are accurate.

    At this writing, estimates for the set of 6 PCBs, with an 8008D thrown in, but no other components, is in the range of 300 dollars. Final price might vary a bit, but I doubt that I could make it go any lower, without making this a one off effort, not to be repeated.

    A friend of mine, is looking into doing a reproduction bezel for the front panel of the chassis. He tells me that there are some challenges, as the original was anodized, and most panel manufacturers, these days, do powder coating.

    Today, I am going to see if I can generate a BOM (bill of materials) in an excell spreadsheet. Except for the 8008 and memory, I think most of the rest of the electronics components are readily available. I plan on sending the BOM to Unicorn, who have indicated, a while back, that they would do parts kits for this project, like they have for the Mimeo/Apple 1. The relay sockets used for I/O ports in the chassis, are available, but expensive – I’m going to see if I can find a way to get bulk price on those from someone.

    The 8B will follow on the heals of the 8H, It uses the same front panel, CPU, DBB, and input boards as the 8H, but requires 4 new boards…

  • new backplane with an extra slot for the memory addressing board. I haven’t investigated in detail, but I hope I can leverage most of the 8H backplane design, making this pretty straightforward
  • new 4K memory module. I already have done the base chip placement for this one
  • PROM board. Cameron Cooper has a draft design, that he says he will let me leverage
  • memory address expansion card – haven’t started
  • All in all, you can see that based on the head start that I have on the 8B boards, this shouldn’t take nearly as long as the 8H has taken, to complete.

    After these are done, there is more SCELBI hardware to be done, a TTY interface, a scope interface and a cassette interface. Power supplies are another potential future project. For now you will need to find a 5 volt and -9 volt supplies. Amperage ratings depend upon the amount of memory and peripherals. According to SCELBI documentation, system with a keyboard, oscilloscope interface, and cassette interface requires the following.

  • 4K memory requires 5 volts at 6 AMPs and -9 volts at 3 AMPs
  • 1K memory requires 5 volts at 3 AMPs and -9 volts at 1 AMP
  • I’m also likely to do an automated front panel controller with a micro-controller, to make loading the memory on the 8H easier. I might be able to reuse my existing PS/2 adapter with a new program in order to accomplish this.

    Brain Board

    Brain Board stock is dwindling, but sales have been very slow, as of late. When the stock runs out, I’ll definitely hold off on making a new run, until demand builds up again.


    So far, interest has been a bit lighter than expected. However I’ve got wind of a couple of super cool SUPERPROTO based projects, that may just jumpstart sales when the projects are publicly announced. Feedback from folks using the card has been positive, with no unexpected problems or issues reported. I also know of one, well known, Apple II hardware designer that is leveraging parts of the design, which I have published in detail on the SUPERPROTO Wiki, for his next efforts. Even though, I get no financial reward from this leveraging, it is gratifying to know that my efforts are of use to others.

    Apple II rev 0

    A rerun of these PCBs is also in the cards, though I want to make a few tweaks, so it will also come after the SCELBI and probably the fully built Mimeo.

    That is all the retro stuff that I can think of, for now – Happy New Year

    More SUPERPROTO ideas

    Sunday, September 2nd, 2012

    Prototypers looking to save money – check out the how I changed the 1101 SRAM tester into a permanent solution, without dedicating a SUPERPROTO board.

    I also added jumper selection of SUPERPROTO superpages to my SUPERPROTO experimenters board. I’m able to change personalities of my SUPERPROTO now, simply by changing out the breadboard and by changing jumpers.