Archive for the ‘8008’ 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

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.

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.

SCELBI 8B Backplane Progress Being Made

Tuesday, June 10th, 2014

Lately. I’ve been making some good progress on the 8B backplane. Hopefully in a few more weeks and I’ll have it in good enough shape in order to declare it finished. I’ll probably just go ahead and get it made when it’s ready, even though I have a lot of work to do on the other 8B specific cards.

There is quite a bit involved in building an 8B chassis and 8B builders can start on the chassis while I finish the rest of the cards. Anyway the CPU can be checked out by jamming in instructions, without memory being present. The front panel, CPU, DBB, and input boards are completely identical to the 8H design and I still have some of those PCBs in stock.

One thing I’m going to have to think about a bit, is whether to make a batch of SCELBI custom sized chassis or not. A BUD AC413 can be made to work, as it is nearly the correct size, just a 1/2″ short, other dimensions being right on.

Status of the other 8B specific cards are:

  • memory expansion – I haven’t started on this one, but it is the most basic of the 8B specific cards, so should take the least amount of time to do
  • 4K SRAM- designed to accept 2102 static ram – this card is pretty far along, maybe half done.
  • EPROM – designed to accept 1702 EPROMs – I have a tested, working layout for this card done by someone else. The original layout artist did a good job, but there are a few things I want to change. I will completely go through it to make the layout details match the original as much as possible.
  • Problems with 8008 serial routines that posted

    Saturday, March 22nd, 2014

    Just a heads up – the serial transmit routines that I have posted with the 8008 applications have serious issues. Though it was working for me, other were using serial ports that weren’t so forgiving and had problems with transmit. Finally Corey Cohen tracked down problems with start and stops bits used with the transmited data. As soon as I get a chance to check out the fixed routines, I’ll be updating all the applications on my 8008 application and BASIC pages. For those of you that can’t wait here is the code for a version that I think will probably work. This version is timed for 2400 baud.

    My OS/X emulator was also broken and needs an update, as well.

    OUTCHAR:

    NDI 177 ; mask MSbit
    CAL BITOUT ; STARTBIT
    CAL BITOUT ; LSB
    CAL BITOUT ; 1
    CAL BITOUT ; 2
    CAL BITOUT ; 3
    CAL BITOUT ; 4
    CAL BITOUT ; 5
    CAL BITOUT ; 6
    CAL BITOUT ; MSB
    LDA ; timing delay
    LAI 200
    OUT OUTPORT ; stop bit
    LDI 100 ; and extra for inter character spacing
    JMP MORE2

    BITOUT:
    OUT OUTPORT
    RRC ; shift to get next bit
    LDI 3
    MORE2:
    LAA ; nop to delay 5 states to make timing work
    DCD
    JFZ MORE2
    LDI 0 ; delay 8 states
    RET

    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?

    SCELBI/8008 Page Update Complete, What’s Next

    Sunday, December 29th, 2013

    Finished the update of my SCELBI/8008 pages with a bunch of work on my new 8008/SCELBI applications page.

    I’m glad I have completed this SCELBI web site update, as it is something I wanted to do for a long time. Now, if I only had time to write a complete guide to building and operating the SCELBI.

    Next up… I have new Apple II rev 0 PCB‘s on hand. The PCBs look good, but I need to build one up to test, before offering the PCBs for sale. I’ve also been cleaning up and repairing a craig’s list Apple II plus purchase. Tomorrow, I hope to have the IIplus done, and perhaps start on the rev 0 soldering.