Any interest in custom 6502-like CPU chips?

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ChuckT
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Joined: 20 May 2009

Re: Any interest in custom 6502-like CPU chips?

Post by ChuckT »

BigEd wrote:
Garth, Chuck:
It sounds positive to me, that Garth (for example) could design a board around an FPGA, publish the design files, and then Chuck (for example) could take that design, and build it either modified or unmodified. In the course of Garth's design process, we would converge on an FPGA netlist and pinout which suits that design: we are hopefully wise enough to make it general enough that modified designs would be possible and attractive (*). If anyone at any stage wanted to build and sell a handful or a truckfull of boards, that would be a good result.

I agree that for confident use, the FPGA design files would all need to be published, with an open enough license that anyone undertaking a design could take a safe copy. All the cores discussed already have an open enough license to allow us to work that way: all the HDL I mention as available is available under redistributable terms. Ideally, as mentioned above, at least one board design would be made similarly available. That doesn't preclude someone from making a proprietary board design and even a proprietary ROM, if they are so inclined, but of course an open sourced ROM would always be my preference.
I would like you to please, please, please consider some of these audio chips for a Single Board Computer using the Spartan or Xilinx FPGA chip with the 6502 Core:

Wolfson ADC WM8782 and a Wolfson DAC WM8523

See:
http://dangerousprototypes.com/2012/11/ ... -breakout/

LA2610 analog surround sound processor
http://www.datasheetcatalog.org/datashe ... LA2610.pdf

I also saw this Gameduino used with the MSP430 Launchpad as a gaming platform and I wouldn't mind interfacing it with an ARM or 6502 board:

http://dangerousprototypes.com/2012/07/ ... amingpack/

I already have several ARM boards, several ARM chips, a Jtag connector and I'm going to order a ST Link after the holidays because it is my goal to build a single board computer. I've already ordered a PS/2 to breadboard connector, an SD card to breadboard component and I have several LCDs to work with. I have been planning and wish to make this a reality. I'm also looking at that VGA board for the 6502 and other chips.

Microchip also has some serial SRAMS:

http://www.microchip.com/wwwproducts/De ... e=en559066

I'm willing to promote the 6502 but these are some of the components I wish to work with so I am constantly working at choosing components and Microchip will also give you information on how to use them if you give them a project idea because they've already given one user information for using it with video.

If you or anyone know of any better or comparible components, please let me hear from you.
ElEctric_EyE
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Joined: 02 Mar 2009
Location: OH, USA

Re: Any interest in custom 6502-like CPU chips?

Post by ElEctric_EyE »

ChuckT wrote:
... please, please, please consider some of these audio chips for a Single Board Computer using the Spartan or Xilinx FPGA chip with the 6502 Core:

Wolfson ADC WM8782 and a Wolfson DAC WM8523

See:
http://dangerousprototypes.com/2012/11/ ... -breakout/

LA2610 analog surround sound processor
http://www.datasheetcatalog.org/datashe ... LA2610.pdf

I also saw this Gameduino used with the MSP430 Launchpad as a gaming platform and I wouldn't mind interfacing it with an ARM or 6502 board:

http://dangerousprototypes.com/2012/07/ ... amingpack/

I already have several ARM boards, several ARM chips, a Jtag connector and I'm going to order a ST Link after the holidays because it is my goal to build a single board computer. I've already ordered a PS/2 to breadboard connector, an SD card to breadboard component and I have several LCDs to work with. I have been planning and wish to make this a reality. I'm also looking at that VGA board for the 6502 and other chips.

Microchip also has some serial SRAMS:

http://www.microchip.com/wwwproducts/De ... e=en559066

I'm willing to promote the 6502 but these are some of the components I wish to work with so I am constantly working at choosing components and Microchip will also give you information on how to use them if you give them a project idea because they've already given one user information for using it with video.

If you or anyone know of any better or comparible components, please let me hear from you.
I'm putting this in my DSS thread for my future reference. Thank you Chuck.
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GARTHWILSON
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Re: Any interest in custom 6502-like CPU chips?

Post by GARTHWILSON »

ChuckT wrote:
I would like you to please, please, please consider some of these audio chips for a Single Board Computer using the Spartan or Xilinx FPGA chip with the 6502 Core:

Wolfson ADC WM8782 and a Wolfson DAC WM8523

See:
http://dangerousprototypes.com/2012/11/ ... -breakout/
These are high-end audio parts, so the number of users who would be interested in having them on an SBC would probably be very limited. They have SPI though, so they could be put on a separate board connected via 65SIB, an interface which is easy to put on the SBC. Seven devices at once can be put on the same 65SIB without adding hubs. It's very hobbyist-friendly too, which was one of the design goals.

You definitely don't need 16-24 bits to get good audio for gaming though. Even 8 bits can give 50dB SNR which is all the high-end cassettes gave on good music tapes not many years back, and 8-bit sampling can give much, much better frequency response and distortion figures than the cassette at high record levels. My separate computer speakers on my desk which are about 7" high are hardly good enough for 8-bit.
http://WilsonMinesCo.com/ lots of 6502 resources
The "second front page" is http://wilsonminesco.com/links.html .
What's an additional VIA among friends, anyhow?
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BigEd
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Re: Any interest in custom 6502-like CPU chips?

Post by BigEd »

I don't think we're talking about an SBC in this thread: we're trying to find a way to get variant 6502-like CPUs into people's hands. We may need a reference design for something minimal, if only to test that our designs and pinouts are OK, but I don't think it makes sense to pile features onto such a reference design. Enough to boot, show that external RAM works, and (optionally) some minimal peripheral. Better than a peripheral would be an expansion connector. The reason the peripheral is optional is that we could integrate a VIA or ACIA onto the FPGA, if we wished. Even if we don't, we can load a ROM which exercises the CPU without any peripheral: we need nothing more than an 'OK' output pin.

Back to the subject: I'll probably edit the head post, but note that it initially put forward the idea that someone with FPGA expertise could ship a programmed FPGA to someone without, for money. The second idea was to use conventional (volatile) FPGAs and to ship only a programmed EEPROM containing the bitstream. The third idea, by Arlet, was to suppose that programming a serial EEPROM over SPI is easy enough that we only need to produce instructions.

If using SPI is significantly easier than JTAG, we should use that route. We don't want the end-user to have to use any Xilinx tools or any commercial JTAG adaptor: we want the simplest setup assuming only that they have a PC running Windows or Linux, and the ability to breadboard electronics.

There's a USB-SPI adaptor from robotelectronics for about £20 http://www.robot-electronics.co.uk/acat ... B_I2C.html, and hobbytronics do the Bus Pirate for about the same price: http://www.hobbytronics.co.uk/bus-pirate - do have cheaper or simpler ways to program and verify a serial EEPROM? Almost certainly we can bitbang from a parallel port - maybe even use the control signals of a serial port - I think SPI can be run as slow as necessary. We don't expect our end-users to program very many times.

Garth: you asked how big a bitstream file is. It's about 2.6Mbit, apparently. That's 330kByte.

Cheers
Ed
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