Where to start for old 6502 programmer ...

Discussion in 'Programmer's Corner' started by Paul57, Apr 12, 2011.

  1. Paul57

    Thread Starter New Member

    Apr 12, 2011
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    Can someone suggest a suitable microprocessor/development board for a small project I have in mind? Many years ago I wrote software for the Acorn RiscPC (UK members might remember that) and before that the BBC micro (again, this will mean something in the UK) to send and receive SSTV (slowscan television) for ham radio use. The BBC micro was 6502-based and the RiscPC was 32-bit ARM based. I used assembler on both systems. Most modern SSTV systems are PC-based and use the sound card to decode and encode the audio signals that comprise SSTV. I would prefer not to use that method but to try the techniques I used 20 years ago but now on a modern microprocessor. The heart of the system would be to accurately measure the width of every half-cycle of incoming audio (suitably amplified, clipped and applied to a 1-bit input port) in the range 1200 to 2300Hz. Accuracy would need to be around 1 microsecond - a bit better than that would be useful. At the same time, a "pixel clock" would need to run in another timer providing timing points every few hundred microseconds. The accuracy of this clock needs to be about 200 microseconds in about 2 minutes. I can provide a more detailed explanation if anyone would find it useful.
    I guess I am looking for a modern equivalent of the 6502 microprocessor combined with a 6522 VIA. The timers in the 6522 were ideal for this application; you could write a new timeout value into a latch which would then be transferred to the timer on the next timeout. This kind of functionallity would be essential.
    Programming-wise, as mentioned before I can cope with 6502 assembler and ARM assembler. A similar "RISC" assembler should not be too hard to learn. I have not used C, although I don't think it would a major drama to learn enough to get by. I also program in VB6, a bit of VB.Net and Javascript.
    So, any suggestions for a suitable development platform? I know nothing of PICs and other modern CPUs. Where should I start?
    Many thanks,
    Paul.

    EDIT: Not sure if this post should have gone in the "Embedded Systems and Microcontrollers" forum? I guess it's a bit of both really.
     
    Last edited: Apr 12, 2011
  2. beenthere

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  3. t06afre

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  4. Paul57

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    Apr 12, 2011
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  5. GetDeviceInfo

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    Jun 7, 2009
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    6502, wow, where have you been?

    Actually, if I go to the very back of the garage, I know there are several boxes full of hand wired 6502 systems that really should be cleaned out. It's not that bad though, as another early processor, the 8051/2 is very prominent. I can't speak for the 6800/0 though, anyone? Loved the linear addressing.

    You'll be real happy to see where the industry has gone. Basic Risc cores are supplemented with onboard peripherals including timers/counter, comm ports, I/O ports, static and flash rams. Add to that an exhaustive offering of combination and specific task devices.

    I'd suggest going to Microchip and Atmel sites and doing a parametric search for comparison.
     
  6. GetDeviceInfo

    Senior Member

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    I hear what your saying, but I have to add that the 6502, even in it's earliest form, was instrumental in moving the industry forward. There was no bad 6502.
     
  7. qlue

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    Apr 15, 2011
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    Anything a 6502 with it's VIA/CIA chip can do can be done similarly with an Arduino board if you don't mind trying your hand at C :p
     
  8. RiJoRI

    Well-Known Member

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    Yeah, the Arduino with its C-Lite is probably easier for knocking out a QAD (Quick-and-Dirty, kiddies!) system, but for some there is a romance with the old 8-bitters: 6502, 8085, 6809, 6805, Z-80. I still fool around with my 6502-based AIM-65, as well as my 8085-based R/S Model 100. Can I go online with them? No, but then again, who enters a Model A Ford in the Indy 500? And who tries to drive a Formula 1 car down dirt roads? :D

    --Rich
     
  9. hgmjr

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    Jan 28, 2005
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    If you want to get started with ready-made hardware without having to invest in a programmer or software development IDE then I would also recommend you look into the Arduino UNO or Arduino Mega at www.arduino.cc. If you want to see some interesting projects then go to youtube and type in arduino as the search keyword.

    hgmjr
     
  10. Paul57

    Thread Starter New Member

    Apr 12, 2011
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    Thanks for the Arduino info guys. Looks very interesting.
     
  11. DumboFixer

    Active Member

    Feb 10, 2009
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    If you are after an old 6502 programmer - look no further, I'm here :)
     
  12. Paul57

    Thread Starter New Member

    Apr 12, 2011
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    As this thread has been nicely revived I'll ask another question: Both the Arduino and "Microstick" (from Microchip) boards look very interesting. One thing I'll need to do is to transfer data via USB to a VB.Net "front-end" program running on a PC. Can either of those boards cope with that? I will need to transfer about 1KB of data every 400mS or so. I will only have about 3mS of "spare" processing time (on the PIC board) to initiate the transfer, so hopefully it will just be a case of quickly writing the data into a buffer. I may be being optimistic about how simple this will be ;-)

    Thanks for any further information.
     
  13. Paul57

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    Apr 12, 2011
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    It must be at least 20 years since I did any 6502 programming (on the BBC micro) but those wonderfully simple instructions are still as fresh in my mind as the day I learned them; LDA, LDY, LDX, TXA, TAY, BNE, BEQ ... what more could you want? :)
     
  14. beenthere

    Retired Moderator

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    A microprocessor that uses that same instruction set. I even had an assembler written in Applesoft Basic.
     
  15. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    and I was foolish enough to spend the better part of a year writing a multipass dissassembler in MSBasic.

    I'm not familiar with the Arduino boards (I etch/mount device specific layouts), but do know that both Microchip and Atmel lineup have USB device/OTG offerings. I personally employ the 89AT5131 in several of my USB devices, and have a couple of AVR USB devices nearing completion.

    Once configured, it's as simple as writing to the buffer.
     
  16. Paul57

    Thread Starter New Member

    Apr 12, 2011
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    Many thanks for the info.
     
  17. cowasaki

    New Member

    Apr 3, 2011
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    You could always pick up an old BBC model B off ebay for a play. I have a couple in the attic :) That evocative double beep when they switch on takes me back years.....
     
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