Replica 1 SE improvements

Talk about your replica, what you have done and what you use it for

Replica 1 SE improvements

Postby vbriel » Mar Fri 17, 2006 8:45 am

One of the reasons I decided to hold off on replica orders is so I could redesign the board. I'm making changes I've always wanted to do but never had time. I've also taken input from replica 1 owners and incorporated their ideas into the design. Then a few things I've just wanted to do.

Here is a list of changes/improvements I've made so far:

1. Serial I/O is now part of the main board.
2. Changing large ATMEGA8515 keyboard controller to ATMEGA8
3. ATX power supply instead of AT
3. Added power LED
4. Added Wall-Wart style power supply option
5. Added on/off switch (previously on AT power supply)
6. Switched serial I/O over to USB
7. Dropped unused prototyping area
8. Dropped unused ASCII keyboard connector
9. Added extra 40 pin DIP with expansion connectors for breadboarding.

I'm considering changing BASIC and the firmware and Woz monitor to have a full BACKSPACE function. I have a replica 1 now that is modified like that and to tell you the truth, it is much better. This really takes away from the apple 1 functionality.

What does everybody think about the changes. Anything I'm missing before I goto a proto board?

Vince
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Postby Kallikak » Mar Mon 20, 2006 8:03 pm

They all sound pretty good to me. I'll be jealous of the new owners! :-)

I've got a power switch and LED, a wall-wart power supply, and a serial I/O board on mine, and they are all well worth having. USB sounds great as well.

I'm not sure about the backspace though - there are lots of improvements to the system that could be made, but you don't want to end up with an Apple II... :-)

Ken
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Postby cheese1113 » Mar Tue 21, 2006 12:43 pm

I think you should keep the ASCII socket. Even though they are hard to find, they really add a nice vintage feel to the computer.
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Postby vbriel » Mar Tue 21, 2006 1:39 pm

Kallikak wrote:They all sound pretty good to me. I'll be jealous of the new owners! :-)


Don't be, there are serial to usb converters out there and the usb chip I'm going to use is just a port converter. It creates a virtual comm port on your machine. Some PC's don't have serial any more and modern Macs don't either. The other changes are very very trivial.

I may keep the keyboard port, maybe make the ATX an optional usage with the wall type power supply as the standard.

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Postby mrbill » Mar Wed 22, 2006 10:42 pm

Sounds good to me - I'll buy one! Look forward to being able to communicate over serial without strange timing adjustments...
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Postby vbriel » Mar Wed 22, 2006 11:59 pm

Timing adjustments.... Well, I never really discussed this in any detail but I'm sure some of you are wondering why you have to add the delays. Well the long answer is because of the apple 1. In my attempt to replicate the apple 1 I kept the I/O identical so software would be 100% compatible. When I came up with the idea of intercepting the I/O data to the serial port, I was stuck with the speed that the video outputs, 60cps. Also, I had to deal with the serial in to the replica simulating an ASCII keyboard which has a slow data rate. So, in my attempt to make the serial I/O board compatible with an Apple 1 I made it attach right at the 6820/21 PIA making it all possible but the speed had to be just right or data would get lost.

The new replica SE won't be a huge difference. The serial port will be there in spirit. I'm just going to convert the signal to USB and the PC or Mac drivers will create a virtual comm port on your PC. So, still the same screwy settings I'm afraid. I may run some experiments to see if there is anything that can be done about that issue. My biggest reason for the redesign is just to clean up a few loose things. Why change what works? Some people suggested ATX instead of AT. I agree with that but 2 years ago AT power supplies were easy to find and you could get one for $5. Now it is a little more difficult and more people are probably going to have an ATX power supply laying around. This change means adding a switch onboard since it was built into the AT power supply. I'm also adding an LED for a power indicator, Ohhh.... LEDs! On a technical side, I've switched software and the new software I'm using allows for power polygone planes to be added. This improves the power flow over the entire board.

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Postby vbriel » Mar Sat 25, 2006 11:21 am

Ok, I added the ASCII socket to the SE for that authentic look and feel. I also changed the socket pads. Instead of round thru holes for the sockets I changed to oval. This will make it easier for people learning to solder because the pads are slightly larger. The last thing I have to do is create a connector for a wall brick power supply. This now also means adding a 7805 voltage regulator but it will make the replica 1 more compact with a wall brick I think. It will also have the ATX option for those needing the -12V and 12V lines.
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Postby fynch » Mar Sat 25, 2006 4:47 pm

All these are great ideas but the name... eh...

What about the Replica Plus?
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Postby vbriel » Mar Sun 26, 2006 7:14 pm

fynch wrote:All these are great ideas but the name... eh...

What about the Replica Plus?


Really, that bad? Ok, let's open up the forum to a name contest. Name the replica 1. Who has the best name for the revised replica 1? :)

Fynch says Replica Plus. What sounds good to you?

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Postby mrbill » Mar Sun 26, 2006 8:51 pm

The more LEDs, the better! I love blinkylights. Too bad you can't put a bank of them in to indicate CPU activity, etc. 8-)

One suggestion - the holes on the four corners of the PCB on Rev1 were tiny - any chance of making them a little larger on the SE? I had a bunch of PC motherboard standoffs/screws and was dismayed to find out I couldnt use them on the R1 to mount it to a board or enclosure.
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Postby fynch » Mar Mon 27, 2006 2:24 pm

Oh I forgot a suggestion... What about a flash chip or NVRAM for on-board storage rather than storing programs only on a different computer?
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Postby vbriel » Mar Mon 27, 2006 5:35 pm

fynch wrote:Oh I forgot a suggestion... What about a flash chip or NVRAM for on-board storage rather than storing programs only on a different computer?

You can do that now. There is an NVRAM for $10 that replaces the 62256 32K onboard RAM with NVRAM. Your memory will be intact when powered up. To enter basic E2B3R keeps your program when re-entering basic.

mrbill: I thought about a set of latches (3 of them) to 24 LED's for Data and Address status. That would be easy. Unfortunately that would really crank up things in a build so I won't do it onboard. When I get a few minutes free time I'll draw up schematics.

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Postby fynch » Mar Mon 27, 2006 5:55 pm

Why shouldn't the NVRAM be in there by default in the next version?
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Postby cheese1113 » Mar Tue 28, 2006 10:37 pm

I thought about a set of latches (3 of them) to 24 LED's for Data and Address status. That would be easy. Unfortunately that would really crank up things in a build so I won't do it onboard. When I get a few minutes free time I'll draw up schematics.

When you get a chance, please do, I'd love to make that.
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Postby programsynthesiser » Mar Wed 29, 2006 9:46 pm

Hah, the ironic part about all this is that the Apple I was advertised as "no more blinking lights" :P

I bet I could find a way to make that "unused" prototyping area do something really useful...but I guess the extra 40 pin can make up for it.

Also, what about having an eeprom socket on the board? That way, the chip could still be optional, but would let us all expand much easier.

Oh well, it does not look like I will ever have the privelage of upgrading anyways. When I get the money, I will be either building a case or going off onto another project.

Built-in serial is ok, but the eeprom socket would make up for no serial, for me at least.

Backspace sounds fine, especially for people learning on these machines. How do you backspace again? :P Anyways, anyone who wants the old monitor could reflash their ROM, right?

Will the voltage regulator on the board make it capable of handling a 6 volt battery?

SE reminds me of the Macintosh SE. Not like that is a bad thing...

The Replica 1.5? :P
It works!
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