RE: Z80 In Circuit Emulation

   Funny... I was reading a bit more about FPGAs and VHDL and was
wondering if it would be possible to take advantage of existing CPU
cores (a'la OpenCores) and build a system that can emulate a CPU in
hardware, as well as give you additional control over the system and/or
features to aid troubleshooting. Kinda like a Fluke 9010 on steroids,
but with just about any CPU that you could ever need.

   I figured that having control of the emulated CPU would give you the
ability to do things that the 9010 could not, such as pause/resume,
watchdog handling (i.e. while paused, keep writing to memory location
xyz), patch RAM, ROM or I/Os by redirecting read requests, real-time
register and/or memory viewer and dumper.

   You could even read video memory and render it in some way so that
you can "see" a board running without a monitor handy.

   Of course, you could also implement better memory diagnostics and ROM
checksumming/hashing.

   Just the ability to redirect read requests would be great --
something like being able to verify bad ROMs just by loading the ROM
files into the host's memory and intercepting its address range. You
would not have to pull a possibly bad ROM and burn a replacement to
confirm diagnosis. By handling reads and writes to certain memory
areas, you could confirm a bad RAM before breaking out the soldering
iron.

   I see a few FPGA boards that have on-board USB connectivity and
enough (5v TTL-compatible) I/Os on them -- could they be used for
something like this?

   Of course, I know so little about FPGAs that I am not sure if this
would even be possible, and if it were, I barely know enough VHDL to
implement a SR Flip-Flop. But it would be a really nice thing to have
around, I would think...

   Anyway - getting late...

   Peace!

-=- James R. Twine, (spam@jrtwine.com)
http://www.jrtwine.com
http://www.deletefxpfiles.com
http://www.checkfavorites.com
> -----Original Message-----
> From: owner-vectorlist@vectorlist.org [mailto:owner-
> vectorlist@vectorlist.org] On Behalf Of Mark Jenison
> Sent: Wednesday, February 04, 2009 7:24 PM
> To: vectorlist@vectorlist.org
> Subject: VECTOR: Z80 In Circuit Emulation
>
> Hi all,
>
> I've been thinking about creating a setup similar to this:
>
> http://gls1electronics.com/galaga/index.htm
>
> but for debugging Sega XY boards.
>
> Most Z80 in circuit emulators (ICE) are $$$, but I found this one
> which
> looks reasonably priced:
>
> http://tauntek.com/Z80-In-Circuit-Emulator.htm
>
> I'd need to write my own custom software/GUI to simplify testing.
>
> Anyone else try a set up like this or have any advice/opinions
> about in
> circuit emulators?
>
> --
> Mark Jenison
>
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Received on Wed Feb 4 22:55:31 2009