Friday, April 30, 2010

RS-232 / Keyboard Interface Assembly - Working!

The image above shows the first sign of life for this PS2 keyboard interface to an Apple-1 Obtronix. It worked the first time, no problems at all. Note that as soon as I powered up the Apple-1, the interface automatically sent a Reset and a Clear Screen, and you can see that we end up at the prompt, ready for input. The keyboard LEDs lit, including Caps-lock. I then tested the Control-sequences:
RESET = Ctrl + Alt + Del
CLR SCREEN = Ctrl + C, Ctrl + L, Ctrl + R
I am back in business with a working keyboard!

Tuesday, April 20, 2010

RS-232 / Keyboard Interface Assembly

PS-2/RS232 to ASCII Keyboard Adapter Assembly
(designed by Mike Willegal)

I spent about an hour assembling the adapter PCB tonite. I took my time, otherwise I suppose you could build this board in about 30 minutes. I started off by cleaning the board with a tissue splashed with a bit of isopropyl alcohol. I soldered all of the jumper wires first, which took about 40 minutes. This was the most challenging part of assembly, the rest was a breeze. The only thing I have left to do is solder the ZIFF socket (when I receive it). Notice that I used a pair of needle nosed vice-grips to crimp the ribbon cable. This worked perfectly, I was amazed at how it snapped right into place!.


1. Use "helping hands" if you can. Otherwise, tape the PCB to your workbench so the PCB doesn't slide around on you.
2. After inserting the .1uF caps, GENTLY pull the leads through with a pair of small pliers.
3. Cut and strip all of your jumper wires beforehand. (See my previous post)
4. Use really thin solder (e.g. .020)
5. Use masking tape on EVERY component you solder including the jumper wires. The only exception is the RS-232 connector (DB-9), which easily snaps into place before soldering.
7. Check your connections with a magnifying glass and multi-meter (set to measure OHMs) to make sure there are no shorts between adjacent soldering points.
8. Solder a BARE wire between pins 16 and 5v. THEN solder a wire from pin 15 to the bare wire (Thus providing 5v to pin 15).

Sunday, April 18, 2010

Saturday, April 17, 2010

PS2/RS-232 to ASCII Keyboard Adapter cont'd

After reading the instruction pamphlet, I measured, cut and stripped the jumper wires. I decided I wanted to solder these first, before soldering the DIP sockets -- mainly because this board is really tight and I wanted the extra space to work. I ordered a few more ZIFF sockets, which I'll be installing on this PCB as I did with the Apple II keyboard interface. Having a "quick disconnect" from the motherboard is a luxury, but it is worth the extra few dollars it costs to install a ZIFF socket. Unfortunately, I won't have them for several weeks due to a backup in the postal system.

Monday, April 12, 2010

PS2/RS-232 to ASCII Keyboard Adapter

Mike Willegal has done it again. I mentioned awhile back, while working on my A-1 BASIC firmware card, that my Apple II keyboard stopped working. I've decided to replace it with a PS/2 keyboard for now, until I can find another affordable ASCII keyboard. To do so, I will need Mike's adapter. These photos show 2 kits that Mike sent to me. You can see the high quality DIP sockets Mike included in these kits. It's also a good thing he included the 16 connector ribbon cable, because I only have 200 feet-- (I bought some extra just in case I "run out") ;D
Mike's kit includes an instruction booklet, and PCB diagrams to aid in assembly. I will post my progress as I build these kits. (The kits also include wire for jumpering, not pictured)

Saturday, April 3, 2010

Wow! New Apple-1 Memory Test Utility...

Can't get into the Monitor? Tired of RAM chip swapping?
Check out Mike Willegal's Apple-1 Memory test utility!

Comparison: Mimeo PCB to Obtronix PCB

Mike Willegal's Mimeo is on the left, underneath Stephen Gabaly's Obtronix board on the right.
The inset is an original Apple-1. Aside from the obvious Apple logo differences, note the trace differences; The Mimeo has thicker traces, and rounded corners, vs. the thinner and more jagged traces found on the Obtronix board.
Also note the stencil differences and the via diameter differences.

Mike Wllegal's Mimeo

2 Mimeo boards end to end, front and back.

Obtronix Apple-1 Reproduction Kit Instructions

These kits came with instruction sheets. My first kit did not, but I was able to find the instructions on the internet. (They were posted on my blog as well sometime in 2009).

Obtronix Apple-1 Active Parts Kit (chips & regulators)

Obtronix Apple-1 Reproduction Kits

2 Obtronix kits crammed into one box (as I received them). One bag of parts omitted in the photo as I put them in another box for obvious reasons. When the kits arrived, the ribbon cable pins were bent, so I straightened them out, placed DIP sockets on each end, then capped the pins with antistatic foam. I put all of the parts back into a large ziploc bag.