Printing from an Apple-1?

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Joined: Mar 6 2013
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Folks,

Do you know whether anyone has modified an Apple-1 computer (or replica) to allow printing?

Sounds to me that at a minimum I would need to extend Wozniak's Monitor to be able to support printing.
And then add support for a parallel port as well.

Just curious to see if it you know whether this has been done.

Thanks,

rookie2013

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Joined: Jun 5 2008
Posts: 380
Re: Printing from an Apple-1?

You'll see a number of original Apple 1's had wires running from the 6820 PIA to the proto area. Often this was to support a printer. Basically, when the printer was on, it would intercept data bound for the terminal section and print it. No need to modify the monitor or BASIC. A common printer of the time was the SWTPC PR-40. Wendell Sander designed a serial board using a clever hack of the Apple 1's VMA line. The serial board could be connected to a serial printer.
http://www.apple1notes.com/old_apple/Peripheral_Boards_files/Apple%201%20Serial%20Board.pdf

regards,
Mike W.

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Re: Printing from an Apple-1?

I read the title and immediately thought of Mike's registry. Scroll down to Unknown Whereabouts. The third one in the list, Fred in Louisiana, shows an example of the addition of a printer interface to the proto area.

http://www.willegal.net/appleii/apple1-originals.htm

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Re: Printing from an Apple-1?

There's also some history on printing from the Apple I in the first chapter of Apple I Replica Creation:

http://www.applefritter.com/replica/chapter1

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Posts: 380
Re: Printing from an Apple-1?

Editorial Comment: Sad to say, but that unit no longer sports the wires required to connect the printer. It was cleaned up and returned to as close to as shipped condition as possible for the Breker auction. I guess the value goes up in that condition, but some of the history of the unit is lost. Maybe, someday, buyers will value systems in as used condition more than as shipped and sellers will start leaving any modifications in place. Given the amount of money received, I can't blame the seller, but it's still a shame.

regards,
Mike W.

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Posts: 1048
Re: Printing from an Apple-1?

What I would suggest is to not modify the board, but use a 40 pin IDC dip socket and cable and make a small daughter board that you can put the 6820 on and the latches and strobe logic for a printer. This way your not messing with the proto-area and you can keep your board clean. The proto-area pads aren't heat-sinked to any traces so it's very easy to lift one if you aren't careful when you solder or desolder it. You see this on most of the Apple-1 which have been returned to original condition that they are missing pads either from back in the day when the proto work was done or when removing stuff.

Cheers,
Corey

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Re: Printing from an Apple-1?

To print you only need to monitor the data being sent to the display which can be done by monitoring the activity on the peripheral connector. So if your printer can stay ahead of the Apple 1 display rate of 60 Char per second (about 480 baud) you can build a printer card without touching the Apple 1 board. You can also provide a handshake from your peripheral with a TTL driver since the 6820 output can easily be overridden by the peripheral although this is not really legit. The USB card I describe operates a little faster than the 480 baud so it will work without a VMA mod although it might be that a character will be occasionally missed I have never seen a problem.

On the subject of board mods, I have an original Apple 1, a clean fairly accurate Mimeo, and an everyday Mimeo. I use the everyday Mimeo for all my experimentation, to evaluate board mods etc. The accurate Mimeo is used to illustrate what an Apple 1 board looked like when it came out of the box. I have the VMA mod on the clean Mimeo because you need a microscope to see the change. By having the VMA mod I can expand the memory and use my Laptop for the display by simply using add-on cards. I never touch the real Apple 1, not even putting on an expansion board because it would mark the connector. The Apple 1 was moded to 32K about 1980 so it will run my large basic programs and that is all I do in a demo of the real Apple 1. I am the original owner, it was purchased at a Byte shop, and I have all of the original parts although parts have been replaced to keep it running the old parts were kept.

I would advise the the only reason to touch an original Apple 1 is to get it running and to make it safe, like add electrical tape to exposed 110V wires. The only reason to get it running is because it is more valuable if you do. The system should be kept original as possible, the Apple 1 we got running at the San Jose History Museum had a completely different transformer set-up and EMI filtering but it still worked so we used it. Since I have the Mimeos I have no reason to touch the Apple 1 board. Any real Apple 1 owners interested in doing Apple 1 hobby work should get a clone and use that.

Making mods on clone boards that are reversible (particularly if you need a microscope to see them) is fair game in my opinion.

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Joined: Aug 25 2014
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Re: Printing from an Apple-1?

Wow, I got really, really lucky today and scored a SWTPC PR-40 printer on ebay: http://www.ebay.com/itm/SWTPC-PR-40-Printer-Rare-dot-matrix-Vintage-approx-1976-/321642241684?nma=true&si=ib0PqPlpQXQ60iiZK2MFLPNCtEc%253D&orig_cvip=true&rt=nc&_trksid=p2047675.l2557

These do not come up often.

I cannot wait to restore it and mate my it to my Mimeo!

I have a big decision though...should I do an accurate replication of the Interface Age Steve Jobs Apple 1 mod article ( http://cameronscloset.com/category/interface-age/#jp-carousel-258 ), a daughter board at the 6820 socket or a plug in board at the expansion connector ?

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Re: Printing from an Apple-1?

I saw that up in ebay and debated if I should bid. I'm glad now I didn't as I wouldn't have had the time to make an interface for a long while, so I'm glad it's going to someone who does.

I'd make the modification to the Mimeo board just like the Jobs described. Otherwise what's the point of the correct vintage printer to match the article.

Cheers,
Corey

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Joined: Aug 25 2014
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Re: Printing from an Apple-1?

Thanks Corey, I really appreciate your advice. I was definitely leaning toward doing a very neat implementation of the modification, per the article. Once I get to it, I'll post pictures, and a video when it is all up and running.

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Joined: Aug 25 2014
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Re: Printing from an Apple-1?

Well, some of you may have noticed that there was a second SWTPC PR-40 that came up on eBay last month. Since I had learned so much about these machines, and put so much effort into restoring the first one to perfect operation, I figured I might as well use what I learned and restore a second one and offer it to another Apple 1 enthusiast.

I still will post pics and a video shortly. I will be selling this one complete with a dark-printing newly manufactured black ribbon, 10 rolls of NOS paper (ribbon and paper are very scarce), a pre-terminated dip-plug on 4 feet of rainbow period ribbon cable (just as Steve Jobs suggests in his Interface Age article on interfacing the SWTPC PR-40 with the Apple 1 http://cameronscloset.com/category/interface-age/#jp-carousel-258 ), and a period Grayhill DPDT DIP-switch that will mount nicely in the breadboard area of the Apple 1. Sockets and sufficient 28 AWG green Kynar insulated wire will be included to round out a complete kit to perform the printer mod-interface.

Other than a few cosmetic scratches, and a few isolated spots of corrosion, the unit for sale unit is now clean, lubricated, tested and in very good operating condition. All worn or broken mechanical parts were replaced with NOS. The electronics has been repaired and other than three 1/8" holes drilled in the PCB for some misguided repairs that have been removed, the PCB has been brought back to it's original state. It is serial number 0357 on the print mechanism, with an 18-76 date on the motor, so it is a quite early unit.

I prefer to do a direct transaction via PayPal, so make me an offer via PM if you are interested. This is a really nice original working printer kitted with everything you need to get and stay up and running on any of the Apple 1 reproductions. It is certainly a significant piece of early personal computer history and should be along side an Apple 1. If it does not sell fairly quickly, it will go on eBay.

-Steve

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Joined: Aug 25 2014
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Re: Printing from an Apple-1?

Some stills:


NOS mechanical parts include new platen, new rubber paper roller, new motor drive pulley, new pressure plate, new microswitch, and new line feed spring. Printhead on this unit is still in very good condition (slight surface corrosion on housing of solenoid at 10 o'clock does not affect performance).


Main board. White/gold chip is Fairchild shift register. Other large DIP is character generator. Replaced critical printhead pulse timing potentiomter with cermet pot, replaced broken printhead connector with NOS unit and reinforced plated through holes with eyelets, fixed interface timing tolerance problem with resistor adjustment, cleaned excess flux from solder side, re-soldered questionable solder joints.


Power supply board.


Actual printout from this unit after restoration.


Typical Apple 1 location for interface plug and DPDT switch