I have a Rev C Replica I board with Serial daughterboard that I put together a little shy of a year ago and finally got around to finishing it off. I had some broken socket pins which I have since replaced or repair and it seem to power up fine using a recently aquired AT power supply. Two problems:
1. I get this strange character "fade" (for lack of a better term) after the computer is in use for about 10 minutes. I found a thread on a similar problem [characters's dropping in video - help, 4 June 2005] which I will look into further.
2. I am using a generic PC PS/2 keyboard and getting strange character mapping:
keys-> 1 2 3 4 5 6 7 8 9 0 - =
char-> T U ; / 3 * W F
keys->Q W E R T Y U I O P [ ]
char->V M S
keys->A S D F G H J K L ; ' (return)
char-> 9 $ Y
keys->Z X C V B N M , . / (R shift)
char-> G O K [ Q H
Futhermore, with each key press I get two characters displayed i.e. Press Q, get VV, Press 1, get TT...etc.
The problem is persistant and repeatable and does not seem to change by wiggling any connectors.
ideas?
The keys/character list didn't come out right in the above post. There are no characters mapped at the follow keys: 5,6,9,0, E-O, ], A, S, F-;, B thru (,)
The Space Bar = ' and Right shift = H
Clear as mud?
Unable to find problems with my solder joints, I picked up another PS/2 keyboard from a local thrift store and now my replica 1 works.
Both are no name generic keyboards but the only difference I see is the first 'board had keys for both power and 'wake' where the second appears to be just a PS/2 version of the AT keyboard.
Right now I am running the Replica 1 using a 7805 regulator fed from a 9VDC battery while executing a nested loop BASIC program I threw in to see it go. Vince, if you haven't finalized your SE boards yet, regulator has been working great using a multi-voltage DC wall-wart from Radio Shack, perhaps you can incorporate it into the design and eliminate the ATX power supply 'stuff' all together.
Finally, I would like to thank all those Replica 1 builders out there who offered their assistance...
Is that sarcasm?
Actually I did add a 7805 T series voltage regulator to the project but I also have an ATX option. The reason is because if somebody needs the -12V you're not going to get it from a 6V wall wart. It wasn't that difficult to keep the ATX connector on the board for those who need the extra voltage options.
I just received my final prototype boards for the replica 1 SE and I'm testing it now. I think most everybody will like the improvements and the added flexibility of the circuit. I should be able to start taking pre-orders on the first run in about a week or two.
PS, let me know how long it last on 1 9V battery. Also, did you add a heat sink, I'm sure the voltage regulator gets a little warm going from 9 down to 5V.
Vince
My apologies... After I posted I was flipping through your site again and I realized the picture of the Replica 1 SE. I have been having fun with the my rev c (too much for I have a fence to build).
I was considering building a simple 5 and 12 VDC supply using a radio shack 18 VDC wall wart but if the -12 is only for the ASCII keyboard, I'll pass. I need to do something since using the AT power supply is too monsterous to display the computer with the rest of my collection.
I was able to get the Replica 1 to run off a 9V battery through a 7805 regulator for over 2 hours while continously running a program (simple counter). This battery was in a new package but had been sitting in my electronics stuff for a few years. Output was to a Apple II monitor and the picture was relatively sharp and clear. I did step out for about 30 minutes during this time and when I came back the computer was off and the regulator output was zero. Can't tell you how the computer reacted to the gradual loss of power.
The supply has a small heat sink but was cool the the touch. It is my understanding that the package regulator is designed to operate with a Vin 3-4 volts higher than Vout for better feedback. There are many more here that can speak intelligently about this, I have cave man knowledge on the subject . I did some experimenting using different input voltages however and found that the Replica I didn't seem to work too well with Vin voltage below 5 vdc. Vout would come close to 4.5 VDC and I would get hangups, dropped video signal, and poor keyboard response.
Right now I have a Belkin serial adapter that Z-Term will not recognize as a com port so I am unable to download the programs to the computer. I have to say that without a text editor that uses backspace I found it extremely frustrating to enter code on account that my typing is so horrible. Will this feature be available as standard on the SE?
Thanks again for all the time you have but in to making this replica computer (you too Tom). I have been wanting to build something like this for some time now and it has really blossomed into a whole new hobby.
Aaron
I will make backspace available for those who want it as a special request. It requires a mod of basic and the monitor to see backspace as a backspace instead of the underscore. _ is the current backspace and works. Whenever you press underscore in basic or the monitor it prints the underscore but the system see's it as a backspace. It's a mental thing. Visually it doesn't backspace so it can be confusing.
I've heard that Belkin has a problem with Z-term before. The built on serial to USB adapter will be an option on the SE and I've been hearing that it works great with Z term. It does the same thing; creates a virtual comm port. So, drivers will be included with the SE.
4.5V cut off. I programmed the video and keyboard encoder to shut down if the voltage drops below 4.5V as a protection. What you are seeing is normal for the voltage drop. You might want to head over to Radio Shack and pickup a 4 C cell battery tray that they sell for $1.99 and try that option. That gives 6V and will do a great job and should give you hours of run time. I may start test with this option and see how long rechargables last.
The 7805 is designed to run between 6 and 12V but if you drop from 12V the heat is pretty high and you will need a heat sink. 6V stays cool and doesn't require any heat sink.
I should have some add-on devices by the end of summer just in time for those long winter days when you get snowed in. Also, Rich Dreher is working on a compact flash adapter for the apple 1/replica 1. It should be a nice piece of work when finished! Somebody will need to write an OS for it!
Vince