Dear friends,
before the summer heat makes it uncomfortable to use the soldering iron, I would like to share my latest project: Apple-1 2513 CHAR ROM Replacement.
There are already a few around, I know, but this version takes into account the unique conditions of the Apple-1, meaning the presence of negative voltages on certain address lines of the ROM.
That' s not unusual, it's that way "by design" and as long as you're using 2513 ROMs there are no problems.
Troubles can come when using traditional EPROMs (2716) or EEPROMs (2816), which do not like the negative voltage input at all.
And since signal conditioning is always a good thing, I decided to add a bunch of Schottky diodes that I had in my drawer: problems solved.
You can find all you need for the realization, including diagram and PCB, at the address:
You can find also a small video with the prototype in use.
Enjoy! :-)
thank you very much for your commitment.Most people will surely have tried to get an original IC to make it look like the original.But it is good when there are technical replacements.thanks Mikel
Hi everyone,
I decided to make a replica of apple-1.And here is a question, I have a possibility to buy a character generator with mark 2513-005. Is this IC suitable for replica Apple-1 ?
There may be more suitable threads for this question...
I believe the 2513-005 contains lower case characters. It should work, but an all-lower-case display will look "footloose and fancy free" as the saying goes.
Scratch that, it has a completely different character placement. So it will not give legible text.