Re: has anybody tried to replace a vic or vic II chip with a board containing a propeller ?

Jim Brain <brain@jbrain.com> writes:

>   * Finding 5V CPLDs is getting harder (Xilinx has EOLed their XC9500
>     series, and the 9500XL is 3V3, for example).  Of the parts that
>     remain (and NOS XC9500 stuff), the prices are significant for the
>     paltry number of effective gates you get)
>   * Assuming you continue with a 3V3 part, you need to add voltage
>     translators.  They're not all that expensive, but sometimes board
>     real estate on a small DIP-sized board can be a problem.

The 9500XL series CPLDs are 3.3V devices, but their inputs are
5V-tolerant. The EasyFlash 3 uses a 95144XL with no additional voltage
translators, the Chameleon actually uses a 9572XL (I think - it's from
that series, but the exact device may differ) mostly as voltage
translator for its non-5V-tolerant FPGA.

> Another option that I have not looked at is a small fab run. If someone
> had a synthesizable CIA, 6502, or VIC-II netlist, I'd be willing to
> explore a small CMOS run.

The netlist that was reverse-engineered by the visual6502 project has
been successfully synthesized into an FPGA, see

https://github.com/pmonta/FPGA-netlist-tools

It may not be the best option for creating a new chip though - the
original netlist probably won't work on anything but an NMOS process and
the FPGA version is basically a parallel mixed-level (gate/switch)
simulation of that netlist which needs a fast auxiliary clock (50+MHz)
to run and uses a lot of space compared to a manually-implemented 6502
core in Verilog or VHDL.

> It would no doubt cost many thousands (maybe too many to even
> consider), but might be worth it for a community effort on high
> value/high interest ICs if the price could be amortized over the
> number of ICs produced.

I think you're off by an order of magnitude or two. MOSIS has an online
automated quote generator - 30 chips (minimum) in the ON Semi I2T30
process (0.7um CMOS, the largest in the list; no idea if it would be
suitable) with 1mm^2 die size (random guess): 158160 USD (including
overnight shipping)

-ik

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