Archive for the ‘8008’ Category

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.


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

    RRC ; shift to get next bit
    LDI 3
    LAA ; nop to delay 5 states to make timing work
    LDI 0 ; delay 8 states

    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.

    SCELBAL Page Update

    Friday, December 27th, 2013

    Mark Arnold sent me a paragraph with the story behind SCELBAL. My original explanation was incorrect and has been replaced by Mark’s story. Check out the update.

    SCELBI/8008 Web Pages Get Update

    Wednesday, December 25th, 2013

    I still need to add a few 8008 applications I have working to the applications page.

    Rev 0 Repro Progress and Retro Workshop Update

    Saturday, November 30th, 2013

    Apple II rev 0 Progress
    My revision of my original reproduction, the Apple rev 0, is coming along. This morning, I did an extensive design review of the 35th revision, and only found 3 things that needed “fixing”. I’ll probably repeat the effort tomorrow on revision 36. Hopefully that review passes cleanly. If so, I’ll get quotes, pick a vendor and kick off board fabrication next week.

    Projects in the Lab
    Like usual I have a lot of other projects in progress. Some have been in progress for while, others not. Here is a snapshot of my workshop. It keeps getting more crowded as time goes on.

    My Retro Workshop

    My Retro Workshop

    My “LAB” is currently setup for checking out the SCELBI TTY card, which is interfaced to an Apple II serial card, which also supports 110 baud current loop. The hardware is working, but I have to do some software work on the Apple II side of the serial current loop connection in order to make it usable. The standard Apple drivers seem just a bit quirky,as they are tied into Apple II monitor functionality. I was hoping to get by with Apple’s standard PROM drivers, but it looks like I’m going to have write a custom driver for interfacing to the SCELBI. I’m hoping to get the IIe running such that it works just like a real TTY, perhaps eventually including emulating paper tape using floppy discs. I decided to use the IIe instead of a II or IIplus because it supports 80 column output without extra plug in cards.

    SCELBI Galaxy
    I was hoping to make a video of the SCELBI running tiny SCELBAL basic and the SCELBI Galaxy program, which I recently got running. The Galaxy program is SCELBI’s version of the Star Trek game. It was published as documented source code in the SCELBI book “Galaxy”. I had to OCR a scan of the book and then covert it to the AS8 assembler format that I prefer. This took a considerable effort, but I was able to exactly reproduce the original program. When I first went to download it into a physical reproduction 4K SCELBI 8H, I discovered that there wasn’t enough room in memory for a boot loader and the game. I had to spend a lot of time creating a second version the source code to make it fit into 4K with room for a boot loader, without altering the play of the game. This was particularly difficult as the originally published source, didn’t have labels attached to any of the messages, just hard coded addresses pointing into a huge block of characters. In order to move anything in memory, I had to convert the hard coded addresses to labels and add the label to original block of bytes. Oh yeh, there were some page boundary assumptions that I also had to deal with. It wasn’t easy. Once I get the Apple IIe TTY emulation going, I’ll definitely make the video of both the Galaxy game and tiny SCELBAL running on the 8H.

    SCELBI Webpage Update Coming
    I have an update to my 8008/SCELBI web pages coming. Right now, there is too much on my 8008/SCELBI page and I’ll break it down to a few smaller pages. One page that needs a lot of work is the SCELBI/8008 software page. I have managed to get a number of 8008 programs running, some new and others, like Galaxy, old programs that I believe haven’t been run in decades. I need to set up a dedicated software page in order to share them all, plus the cross development tools that I have used to develop them. Most 8008 software from the era will need to have I/O drivers tweaked in order to run in a particular environment, so I will need to publish source and tools. Some of the software, I didn’t develop, so I need to get permission from creators. I would also like to find time to covert my SCELBI blog posts, along with original documention into some kind of book form, as information about building a SCELBI is rather scattered around. I don’t know when or if I will get around to this, but I am motivated, as I think better documentation might help me to sell more SCELBI board sets.

    Apple IIplus

    Apple IIplus

    Apple IIplus

    At top of the first picture you can see the keyboard for an Apple II plus that I recently picked up as part of a Craig’s list transaction. My intention is to clean up and repair this Apple IIplus for resale. I think it will make a good first II plus system for someone, since it has a pretty late serial number along with an RFI board. My experience with those later systems with RFI boards is that they tend to be more reliable than earlier systems. In fact, except for some keyboard issues, this system came in working condition. As you can see by comparing the inside of the top with the rest of the case, the plastic hasn’t yellowed much, if at all, so it should clean up real nicely.




    Along with the IIplus, I picked up a TRS-80 system, with expansion chassis and floppy drive, along with documentation. It doesn’t work, but it should be a fun project to fix up. I can’t decide whether I will keep or flip it. Initially I was going to add it to my collection, but the engineering isn’t what I’m used to, so I’ve already somewhat soured on it. A friend of mine had a TRS-80 briefly, back in the 70′s, but took it back and got an Apple II. Having played with his TRS-80 briefly in the 70s, is what spurred my interest in having one, now. If I keep it, I’ll need to get a Commodore Pet in order to have one of each of the first machines of the “big three” computer manufacturers of the 70′s.

    I keep telling people that I’m not a serious collector, as I like to work on, learn about and operate these old machines. I don’t usually acquire vintage computers, just to own, which is a sign of a serious collector. However, as you can see from this blog post, I seem to continually find ways to increase my “backlog” of projects.