Archive for the ‘Vintage Computing’ Category

Dover Mini-Maker Faire Experience

Monday, August 25th, 2014

Dover, NH Mini Maker Faire

Dover, NH Mini Maker Faire


Just sharing some experience from the Dover Mini Maker Faire which was Saturday. I had Micro – Chess going on the Mimeo and Dave Ahl’s HI-LO in tiny SCELBAL (integer BASIC) on the SCELBI. It was busy almost the whole day, just a few fairly brief periods between visitors. It seemed a bit busier than Saturday at VCF.

HI-LO was the perfect text game for casual visitors of all ages – simple to teach and quick and easy to play – I was impressed by the number of small kids that immediately proceeded to use a binary search algorythm to find the number.

A lot of people tried a few moves on chess, but the user interface is so awful on the Apple 1 port of micro-chess – I had to train almost everyone – even though I had instructions posted.

I met an original Mark-8 owner(still has his system). That guy added a digital group video card to his Mark-8 and made some improvements to it, which were used by later generation Digital Group video cards. Another person who was into SWTPCs in the day. Another person that was once vice president of the Boston Computer Society. And finally, another guy who worked with Draper Labs on the Apollo guidance system computer.

There was a wide variety of exhibits from art and crafts to a young man who was building a neutron generator. If you have a mini-maker faire in your area, I’d say it would be worthwhile to show off your gear – you might meet some interesting people.

List of all SCELBI PCBs

Wednesday, August 20th, 2014

I plan to reproduce all the SCELBI PCBs. There are 16 types of boards in all. The 1106-1108 8B boards are practically ready to be made. I’ll probably tell the PCB factory to start on them this week. This will mean that in a few weeks I’ll have 10 of the the 16 boards done. The really good news is that most of the remaining cards are only single width, so reproducing them should go much faster than the double width system cards.

Here is the complete list of the PCBs that SCELBI Computer Consulting made and my reproduction status. The peripheral cards are listed in my most likely order of reproducing them

Main System Cards
Reproduced
1100 CPU – 8H/8B
1101 Data bus buffer – 8H/8B
1102 Input – 8H/8B
1103 Backplane – 8H
1104 Front Panel – 8H/8B
1105 1K SRAM – 8H

In progress
1106 Memory Expansion – 8B
1107 4K SRAM – 8B
1108 Backplane – 8B
1109 PROM – 8B

Peripheral Cards
Reproduced
2104 Teletype interface*

Not started
2105 Keyboard
2100 Oscilloscope digital**
2101 Oscilloscope analog
2102 Audio Tape output
2103 Audio Tape read

* not as high as normal vector boards
** double width vector board

Briefcase Apple 1 Sighting

Wednesday, August 13th, 2014

There are a couple of original Apple 1′s that were put in briefcases.

One is owned by the “Main Personal Comptuer Museum” and is depicted on my registry page.

The one of interest for purposes of this blog entry is shown in an image shown on a webpage put up by the Silicium Museum organization. I don’t believe that the briefcase unit is the actual Apple 1 owned by the silicium organization. In fact, since I don’t have good documented images of their unit, I am just a bit skeptical about whether Silicium actually has an Apple 1. My standards for posting original Apple 1 information has risen since I added the Silicium unit, and if I recieved a similar report today, I might not have added their unit to the registry, at least until I recieved a good image.

However, it is interesting that I just got another historic look at this same briefcase Apple 1. It was shown on the program Computer Chronicles, which has it’s shows archived at the site archive.org. It can be seen at the beginning of a show entitled“Apple II Forever”.

I may have to add this unit to the registry, as a missing historic unit. There is a reference in the show to it being a museum piece. Since the show might have been taped in California, maybe it’s still sitting in some museum vault in the Bay Area.

By the way, there is no better way to understand the history of personal computers than to read vintage publications and view vintage videos. The archive of “Computer Chronicles” show is priceless. Check out Bill Gates participating in the Computer Bowl II.

SCELBI 8B update

Monday, August 11th, 2014

Hi SCELBI fans,

Based on scarcity of reports, it may not seem like it, but I am still actively working on the SCELBI 8B card set. It is pretty tedious work, and reporting every new set of tweaks to the layout is not very exciting, so I haven’t been reporting ongoing progress.

To be honest, I prefer exploring new projects, rather than revisiting old ones. Though the SCELBI 8B is “new”, it leverages so much of the 8H design, that it really seems more like revisiting the 8H, than doing something new.

At this moment, I am going through final design checks of the SCELBI 8B backplane, memory expansion, and 4K SRAM PCB layouts. I already have quotes and have done DFM checks with my PCB supplier. I think I will probably build up an very basic 8B system without I/O in a temporary chassis in order to get these cards checked out. This is so I can offer the PCBs for sale for those of you who can’t wait for the whole package. Based on what I know at the moment, I might be ordering PCBs in as little as a week or two from now.

The chassis sheet metal and the EPROM card will come a little later as follow on efforts.

After that, my next efforts will probably be the SCELBI keyboard and oscilloscope interfaces. Those will be “new” to me, so will be a lot more fun to do than the 8B has been. The O-scope interface poses some interesting challenges, as we don’t have any original software for it. We will have to craft some drivers using only the hardware implementation as a reference.

More Vintage Fonts – The SCELBI Front Panel Logo

Thursday, July 17th, 2014

For a while I’ve had an interest in vintage typefaces. This interest stems from my efforts to reproduce vintage literature and the logos.

When I made my SCELBI front panels, one of the challenges I had, was to match the font for the SCELBI logo. Here is an image of the overall front panel.

SCELBI front panels

SCELBI front panel

and a close up of the logo.

Scelbi logo- close up

Scelbi logo- close up

Even though this is a variant of the omnipresent Helvetica, finding a digital font to match was harder than you think. After searching through dozens of variations of Helvetica and derivative fonts, in the end, I choose to use the very similar Helvetica Black. In some cases in the past, I have used Adobe Illustrator to manually recreate logos and such, but recreating characters accurately is extremely difficult and it is vastly easier to use off the shelf fonts.

Scelbi Logo in Helvetica black font

Scelbi Logo in Helvetica black font

It’s a pretty close match, but in reality the original logo’s characters are just a bit wider, so it’s not perfect.

I’ve known for a while that the single largest source of typefaces for printers and advertising people back in those days was Letraset brand rub on transfers. Back in the day, anyone that had anything to do with the printed word, would have had a Letraset reference manual, which contains hundreds of fonts and other visual goodies. Vintage Letraset manuals are available from used book sellers and even on ebay. Recently I picked up a 1981 edition.

Letraset Reference

Letraset Reference

One the first things I did when I got this guide was to determine if I could find an exact match for the SCELBI front panel logo. Here is what I found on the page with bold type Helvetica fonts.

Letraset Helvetica Bold

Letraset Helvetica Bold

If you ask me, plain old Letraset Helvetica Bold is an exact match and was the source for the lettering on the original panels. Now I’m just going to have to figure out the best way to digitize and scale the example letters found in the Letraset guide for my next batch of front panels.

Keyboard Gizmos

Tuesday, July 15th, 2014
parallel keyboard gizmos

parallel keyboard gizmos

Here is a popouri of parallel keyboard projects that I have been involved with designing.

Not shown

  • A simple single chip AVR PS/2 to parallel keyboard adapter that I forgot about when I assembled the items for this picture.
  • At top is:

  • A reproduction Datanetics keyboard
  • At bottom, from left to right…

  • Home etched/prototype PS/2 to parallel keyboard adapter
  • Production PS/2 parallel keyboard adapter configured for Apple 1/Mimeo
  • Production PS/2 parallel keyboard adapter configured for Apple ][. The latest version firmware can also be used with other vintage computers
  • Home made Apple ][ keyboard to Apple 1/Mimeo motherboard dongle with clear switch - based on schematic at Wendel Sander's Apple 1 site
  • Production Vintage Micros Apple ][ keyboard to Apple 1/Mimeo motherboard dongle with clear switch. Similar to home made one
  • Corey Cohen’s parallel keyboard multiplexor. Automatically accepts and switches input from two different parallel keyboards to a single destination motherboard.
  • Not shown are a number of projects that I have started, but not completed (yet)

  • Datanetics replacement using modern components
  • MM5740 replacement using modern micro controller
  • And then there are the projects that never got past investigation stage.

  • ADB bus to parallel adapter
  • PS/2 Apple IIe keyboard adapter
  • It’s really hard to imagine that I have spent so much time mucking with simple parallel ASCII keyboard technology.

    Vintage Micros has Apple 1 motherboard to Apple 2 keyboard dongles available.

    Sunday, July 13th, 2014

    I helped with the PCB layout for this cute little dongle. It has a clear screen switch, which isn’t normally available on an Apple II keyboard and does the rewiring necessary to connect a stock Apple II keyboard to an Apple 1, Mimeo or other clone. These are not needed for replica 1s, which has the keyboard pinout necessary to work with Apple II keyboards.

    Here is one in action, hooked up between the keyboard and the Mimeo.

    Keyboard Dongle

    Keyboard Dongle

    They are being sold by seller vintagemicros on eBay: ebay listing

    One word of caution – be sure to connect pin 1 of cables to pin 1 on PCBs. If you reverse them, you will probably blow the 7404 on the keyboard’s encoder board.

    One last thing, I connected pin 4 of the keyboard socket to the clear screen input on the Apple 1. Pin 4 is normally not connected on an Apple II keyboard, but if you make the keyboard encoder mod to use the repeat switch as clear screen input as described on Wendell Sander’s site, it will work without any further wiring changes.

    SCELBI 8B update

    Friday, July 4th, 2014

    Here is a composite image showing the great progress that has been made on the 4 boards that need to be done for the SCELBI 8B.

    Composite Image of 8B Boards

    Composite Image of 8B Boards

    Still a ton of tweaking and fine tuning needs to happen, but you can almost see the light at the end of the tunnel. I also need to find some time to figure out what I’m going to do for the custom chassis.

    The backplane layout is for all intents and purposes done. The memory expansion card is next closest to complete. I haven’t done much with the PROM card, but I’ll do a complete review of it. The curved traces promise to require a lot of effort to match up to the original. The 4KSRAM cards need a lot of work and since the original has curved traces, it will take an extra effort to finish.

    I’ll be at the MakerFaire in Dover, NH Aug, 23rd

    Tuesday, July 1st, 2014

    I’ll have a Mimeo (Apple 1 clone) and a SCELBI 8H clone up and running and if you come, you’ll be able to see and operate them.

    MakerFaire Dover Flyer

    I hope to see you there.

    Brain Board Manual Errata

    Tuesday, July 1st, 2014

    I have a mistake in my Brain Board Manual versions 5.3 (current version) and lower. On page BB:12, the last switch settings are incorrect.

    Dual Bank Mode – Either high bank of Brain Board or low bank of Brain Board is selected

    should be:

    1-ON
    3-OFF
    4-ON

    5-ON
    6-OFF
    7-ON
    8-OFF

    Switch 3 and 4 settings are backwards in the manual. When I get a chance I’ll update the PDF that is on my Brain Board web page. I already printed manuals for the remaining inventory of Brain Boards, so will hand edit those manuals.