Possible to add more features via propeller alone?

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Possible to add more features via propeller alone?

Postby jasonrp7743 » Jun Mon 06, 2016 7:04 pm

Hi All,
I'm still learning the coding part- and I need to do my homework on the propeller. I figured I'd ask here, as I bet some of you gents will know the answer to this question 'off the cuff':

Is it possible to add more features to the Replica 1 using the propeller alone?

For example, if you weren't concerned with maintaining Apple 1 authenticity, could you add color/graphics and maybe even sprite capability to the propeller code in the Replica 1, and then use those features with the way the propeller is connected as-is? What about adding a screen-clear/screen home feature?

Jason
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Re: Possible to add more features via propeller alone?

Postby jac_goudsmit » Jun Tue 07, 2016 6:12 pm

The examples you name are definitely possible and not too hard.

Keep in mind that the Apple 1 was designed as a minimal 6502 computer (CPU, ROM, RAM, PIA) connected to what's really a video terminal. The original was of course black and white, and supported only scrolling and line feed, but since all that video hardware was replaced by the Propeller, you can certainly replace it by something else.

The simplest way to add features is to change the AiGeneric_Driver in the firmware and find the 'out' subroutine. This checks the output data for special codes and takes action upon them. You can easily expand this for example by uncommenting the line " $00: Cls". Then download the firmware to the Propeller and in your 6502 code you can send a code 00 to the output to clear the screen. You can implement special codes to change the text color or background color, or to change the font. It only takes some programming...

===Jac
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Re: Possible to add more features via propeller alone?

Postby jasonrp7743 » Jun Fri 10, 2016 8:34 am

Good stuff! Thanks again Jac!

I'm going to have to buckle down and learn the propeller. I'd bought the propeller learning lab kit at some point, and it came with a pretty hefty text book for learning the propeller. Here's the kit: https://www.parallax.com/product/32305

For anyone that is interested in learning the propeller too- notice, the link above has a downloads section, where you can download a soft copy of the textbook! More good stuff! :-)

I've been meaning to ask- as I've read up on your propeddle project too Jac; How did you learn the propeller? You seem to have a mastery of this chip! Did you use the text I mention above? Or are there other resources you recommend?

Jason
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Re: Possible to add more features via propeller alone?

Postby jac_goudsmit » Jun Sat 25, 2016 1:17 am

I have one of those too, I bought one when I was on a business trip for two weeks and the L-Star project that I had taken with me, stopped working. If you take the WDC65C02 off the Replica 1, you can build your own L-Star on those breadboards. See https://hackaday.io/project/3620/galler ... 8c7f3663bc for a picture. The version of L-Star in the picture has a video output and a PS/2 keyboard input (Parallax items 28050 and 28060) but those aren't essential; L-Star will also let you use the Apple 1 via the serial port. Besides the breadboard adapters and the 65C02, L-Star can be built with only the components in the Parallax Education Kit.

I don't really remember how I learned about the Propeller but I think I must have found out about it around 2009 or so, probably from some article on Hackaday. Around that time I also found 6502.org and the various websites about retro computing, including brielcomputers.com. I bought a MicroKim and a Pocketerm, and when I found out about Dennis Ferron's Prop-6502 project, I made my own version of it on a breadboard by taking the Propeller out of my Pocketerm and the 6502 out of my MicroKim, that was my first ever video on YouTube.

I learned Spin and Propeller Assembler by doing it. I looked at a lot of existing code and experimented to adapt it to my own needs. The Propeller documentation is pretty good, though the Propeller Manual could have been organized a little better with appendices for things like operators. There also is a GCC port for the Propeller, and it would have made things easier if I could have used it, but when I was programming Propeddle, GCC wasn't stable (I actually found several bugs in the Gnu Assembler and proposed fixes for them too), so after some failed experiments, I decided to get Propeddle running with Spin and PASM, and come back to C/C++ later. That's still on the agenda because it lowers the threshold for people who have never worked with the Propeller before, but I want to do some more programming and perhaps design some more hardware first.

===Jac
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