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6303Re: 1802 Emulations

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  • cwardell2000
    Jan 2, 2010

      The propeller is a very novel device, I'm not sure how well that will translate into any commercial success, but it does seem suited to emulating an 1802 based system. The 8 cogs running at 20Mips each seems really powerful at first glance, but the latency in communicating between the cogs and the need to bit-bang serial, spi, and i2c protocols takes some of the shine off really fast for many possible applications. An immediate example is that I'd like to allow for expanding the memory available for the 1802 emulator using SPI 32kb rams, but the need to bit-bang the SPI protocol makes it too slow to support emulating the elf at speeds high enough to support 1861 video emulation. The most pragmatic way to add RAM would be to use parallel interface SRAMS and a set of address latches which would use at least 12 of the 28 available I/O pins. I suppose I could create an SPI interface with an external shift register and a little support logic, but that will likely use just as many pins.

      Those things being said, I'm not aware of any other MCU or FPGA solution that has the potential to emulate and 1802 with 1861/1862 video and somewhere between 16 to 32kb of available ram in a two chip (counting the eeprom used by the prop) solution for a chipset price of around $10.00. Of course the world isn't waiting to buy thousands of 1802 emulators, so this isn't going to drive commercial success for the prop.

      As far as the the Propeller Education Kit, I think it's a really good value, but if you hava a nice breadboard and a nicely stocked part drawer you may opt for just buying the prop chip, crystal, eeprom, and a "prop plug" programming tool as the book is downloadable as a pdf.

      Chris Wardell

      --- In cosmacelf@yahoogroups.com, "J.C. Wren" <jcwren@...> wrote:
      > Brian,
      > That sounds interesting. I also saw those references to the other
      > emulations.
      > I've been writing firmware for 2^5 years, and seen a lot of processors come
      > and go. I looked at the Propellor when it first came out, but I couldn't
      > get myself interested in it. Maybe something like the Propellor Starter Kit
      > that cwardell2000 mentioned might be a way. It's probably that I couldn't
      > find a use for it, and as a viable processor for a mass-market product, I
      > have a hard time seeing a Propellor gaining traction. Maybe it will, or
      > has, like the PSoC has. Problem we find with parts like the PSoC is they're
      > waaaay too expensive for many applications. Paying for unused silicon isn't
      > cost effective when you can use a cheaper part. And it's my unresearched
      > belief that Parallax hasn't been around long enough to guarantee it's
      > continued existence. Cypress (PSoC), TI (MSP430), Atmel (AVR), Microchip
      > (PIC) and NXP (ARM) have all been around a long time, and I don't get too
      > concerned about them not being there tomorrow.
      > Please feel free to correct me. I'm not disparaging the Propellor
      > architecture, just it's suitability as a processor for a long-term cost
      > effective processor for a mass market product.
      > --jc
      > Eagles may soar, but weasels don't get sucked into jet engines
      > On Tue, Dec 29, 2009 at 6:44 PM, Brian Little <bllittle@...>wrote:
      > >
      > >
      > > I am quite active on the Propeller forum and not only is the ZiCog an
      > > active
      > > project there is also work on a 6502 emulator and possibly a 6800. I've
      > > been
      > > toying with the idea of a 1802 emulator. It should be feasible since the
      > > structure of the 1802 is simpler than the Z80 and 6502. It could run on
      > > just
      > > the Propeller with up to a 16k buffer for memory. It may not run at the
      > > same
      > > cycle speed but with the Propeller having 20 mips, it would be close. If I
      > > do work on one it probably have a hex keypad and a NTSC/PAL output with a
      > > possible version with a VGA output since the Propeller does NTSC, PAL and
      > > VGA quite easily.
      > >
      > [Non-text portions of this message have been removed]
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