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P2 -- the perfect chip for retro computers? — Parallax Forums

P2 -- the perfect chip for retro computers?

cbmeekscbmeeks Posts: 634
in Propeller 2
I think I'm not alone when I say I believe many people will be using the P2 for some type of retro-inspired computer design. Oh, I'm sure some people will use it for "serious" work...but for nerds like me, I want to "P2-power" my retro computer designs.

I'm reading through the Google docs now but I had a few questions to get me started.

1) Would the P2 be able to act as main memory for a 6502 (or even M68000) based computer? I know the P1 could do a 6502 as main memory but was limited to about 1 MHz. More specifically, do you think the P2 could be main memory for an 8-10 MHz M68000 homebrew? I was thinking of using it as 128K of video RAM for a M68000 computer I am designing.

2) Similar to question #1...do you think the P2 could act as glue logic for an 8-10 MHz computer? I'd rather use the P2 than CPLD's or FPGA's if I can.

3) The P1 is great at VGA. I assume the P2 is astronomical. What kind of VGA resolution/depth are you guys getting with minimal cores?

I'm sure I will have more questions later.

Thanks!

Comments

  • ke4pjwke4pjw Posts: 1,079
    One of my first projects this winter will be to interface it with my Color Computer 3 to emulate hardware such as serial ports, floppy/hard drives, SID sound, etc.
  • Peter JakackiPeter Jakacki Posts: 10,193
    I joined the 6502 forum the other day and decided that I would implement a 6502 on a P2 which would also emulate ACIAs and VIAs as well as support 640x480x8 VGA. Just for fun. The P2 is more than fast enough in this regard so it will probably run faster if needed than a normal 6502 and I will probably end up emulating the 65816 too.
    I'm calling this project the 65P2 :)
  • ke4pjwke4pjw Posts: 1,079
    Peter Jakacki wrote: »
    I joined the 6502 forum the other day and decided that I would implement a 6502 on a P2 which would also emulate ACIAs

    Very cool! The 6551 is going to be my first project :) Something tells me you will beat me to it.

  • PropGuy2PropGuy2 Posts: 358
    Limited and *retro* thinking! Let's shoot for something big like a Tablet format: Big touch screen, Apps, maybe some type of Web communication. All hackable of course. Plus, what a great showpiece for the new P2 chip!
  • Wuerfel_21Wuerfel_21 Posts: 4,492
    I think the P2 will do a good job emulating many 8 bit machines wholesale, thanks to the large-enough memory and XBYTE.
    Graphics wise, graphics data can be streamed from hub ram straight into the DAC channels, so the main bandwidth limit from P1 that prevented you from doing 1600x1200 all the time is mostly gone. Also, it's now format-agnostic, it can convert RGB into YPbPr or NTSC/PAL in hardware. Also there's instructions that can speed up common graphic operations (BLNPIX & friends, RGBSQZ/RGBEXP, WMLONG, RCZR)
  • cbmeekscbmeeks Posts: 634
    Well, to be clear...I'm not so much interested in emulating the CPU's. Maybe some serial chips. But I'm mostly interested in using a real 68K and use the P2 for VGA/video RAM.

  • ke4pjwke4pjw Posts: 1,079
    PropGuy2 wrote: »
    Limited and *retro* thinking! Let's shoot for something big like a Tablet format: Big touch screen, Apps, maybe some type of Web communication. All hackable of course. Plus, what a great showpiece for the new P2 chip!

    If that's your itch, scratch it! My itch is retro computing and light controllers.
  • potatoheadpotatohead Posts: 10,254
    Hey all. I am still pretty deep into a startup. I hope to be back doing more with p2 that I can share.

    I definitely want to make a bench computer with P2. Retro projects are a given, but I feel P2 may just have a place on the bench.

    With a few nice connectors, reasonable battery, some built in display, trak pad, keyboard, etc... it could easily perform quite a lot of useful tasks, many concurrently.

    Some of the projects here are already showing all that off.

    It will be very interesting to see what the retro inclined people do. P2 is a nice step up from P1. Heck, one on a card, for those retro machines that can take one, could do a lot. Maybe too much? Nobody knows.
  • AJLAJL Posts: 515
    cbmeeks wrote: »
    Well, to be clear...I'm not so much interested in emulating the CPU's. Maybe some serial chips. But I'm mostly interested in using a real 68K and use the P2 for VGA/video RAM.

    Direct output of HDMI is also possible from the release P2, so with the right frame buffer structure you could output simultaneous VGA and HDMI. If the code is sufficiently lean you could have almost all of HUB RAM for frame buffer.
    With the smartpins, multi-port serial chip emulation (or multi-serial chip emulation) should be possible in one COG without any interference with the video output. Choosing the right P2 sysclk rate would require some attention to get all of this working together.
  • msrobotsmsrobots Posts: 3,704
    I was able to get two serial driver into one COG with buffers in the COG. Now I am fighting with the streamer, In both cases I tried with different clock settings on top of the usual 180Mhz. It is very interesting how granular the settings are and as far as I could test it, it does work like charm, stable over days with lower and faster settings.

    Quite nice for testing, slow clock or streamer down and you can watch your bits on LEDs for debugging.

    As soon as I have wrangled down the streamer, I will try to understand the whole xbyte and interpreter shebang.

    Like with the P1 one does not just to read and understand the description on how to use the goodies, but has to grook chips thinking why he did things that way. That is for mortals like me the bigger challenge.

    But my guess right now is that emulating other instruction sets will be a breeze to do and as eric shows with his RiscV compiler even very fast.

    Somebody already started a Z80 emulator, but got quiet, so not sure about the state of things. @Cluso99 wants to push the envelope by emulating a P1 on the P2 which then emulates a Z80 and will run CP/M. That's a challenge...

    And using a real 6502 and a P2 for RAM and CLOCK an I/O will be also quite fast using the streamers, each cog has one...

    good times,

    Mike
  • Cluso99Cluso99 Posts: 18,069
    msrobots wrote: »
    I was able to get two serial driver into one COG with buffers in the COG. Now I am fighting with the streamer, In both cases I tried with different clock settings on top of the usual 180Mhz. It is very interesting how granular the settings are and as far as I could test it, it does work like charm, stable over days with lower and faster settings.

    Quite nice for testing, slow clock or streamer down and you can watch your bits on LEDs for debugging.

    As soon as I have wrangled down the streamer, I will try to understand the whole xbyte and interpreter shebang.

    Like with the P1 one does not just to read and understand the description on how to use the goodies, but has to grook chips thinking why he did things that way. That is for mortals like me the bigger challenge.

    But my guess right now is that emulating other instruction sets will be a breeze to do and as eric shows with his RiscV compiler even very fast.

    Somebody already started a Z80 emulator, but got quiet, so not sure about the state of things. @Cluso99 wants to push the envelope by emulating a P1 on the P2 which then emulates a Z80 and will run CP/M. That's a challenge...

    And using a real 6502 and a P2 for RAM and CLOCK an I/O will be also quite fast using the streamers, each cog has one...

    good times,

    Mike
    No. Not quite.

    I want to run spin1 compiled bytecode on P2.
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