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Hello,
This is my first forum post. I wanted to say hi and introduce myself. My name is Mateusz and I am from Poland.
Recently I have wanted to build my own versions of "replicas" Apple 1.
PCB board made of publicly available gerberas. Most TTL ICs from my own old stock. Instead of DS0025, I used DS0026 from my local store. Capacitors C5 and C6 according to the scheme - 1uF.
I built two versions. One on the AM1404APC in DIP, the other on MM1404AH in TO99. Both versions work fine. RAM chips are MK4027. In one version there is a MOS 6502A processor, in the other one, a counterfeit MOS 6502 bought in China (which also works!). Oneshot from 74123 is 480ns. (47pF mica and 19KOhm).
Unfortunately, I do not have a working 2519 chip, so I used a "prosthesis" 6x4557 (SMD and DIP versions). Works flawlessly. "Prosthesis" is also used in the second copy. Instead of PROM, there is EPROM on a small PCB, similar for the 2513. It is quite convenient, because you can easily and cheaply test various modifications without wasting the precious 82S129 (etc).
The computers started up without any major problems, but I read a lot of valuable advice from this forum before getting them started. Thank you very much for that.
I invite you to view photos and a short film.
Best regards,
Mateusz / SQ9PXB
IMG_20220623_142612.jpg
IMG_20220624_100954.jpg
Hi,
Your workmanship looks beautiful.
I also do not want to build a computer that is identical to the original, although I try to reproduce it as faithfully as possible. Regarding the character generator chip, this is the "counterpart" of Tesla and RFT (unfortunately I don't remember their symbols), they have a different pinout, but they work.
As for the power supply - instead of the "original" ~ 12V transformer for the LM323K stabilizer, I used a ~7.5V transformer, so my stabilizer practically does not heat up. I don't have to worry about damaging it (and thus practically the entire computer). I recommend this solution instead of using ugly and noisy fans.
I saw Uncle Bernie's "reliability mod", and it is applied, but the computer works without it, too. I know from my electronic experience that these capacitors are necessary and I would use them that way. I see you have a slightly different version of the 6x4557 than mine - I like yours better.
On Aliexpress I was buying:
2513 - works
6502 - works (5 pcs), although it looks like a fake
MK4027 - does not work
AM1404APC from IC BOOM Store - from 10 pcs 8 works. (But immediately after my purchase, they increased the price 5 times)
MM1404 from another seller - did not work (the price was very low)
I bought a few AM1404APC (20 pcs) at https://www.yoycart.com/ at a sensational price of $ 2.4 apiece. They had several hundred pieces, but everything changes dramatically there, you have to search and ask.
Regards,
Mateusz / SQ9PXB
Hi there,
IZ2FER here.
Excellent work, my congratulations!
Enjoy with it!
73, Claudio - P-LAB
PS If you wish, take a look at my projects ( https://p-l4b.github.io/ ), maybe you will find something you need! :-)
Hello Claudio,
Of course, I know your website and admire your projects. They're awesome.
Thanks for this! Great work!
73!
Mateusz / SQ9PXB
Well now I make it 3!
K9BUB here :)
73
Bill