USB MegaDrive DevKit

For hardware talk only (please avoid ROM dumper stuff)
prophet36
Very interested
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Location: London, UK
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Post by prophet36 » Thu Dec 19, 2013 12:49 am

Hi Kaneda,

The UMDKv2 software itself will run nicely on Linux, Windows and MacOSX, but it requires a build of GDB with some modifications so that the disassembly appears in a sane format - that may be tricky to build on Windows but once I've got it working OK on Linux I'll give it a try.

Chris

KanedaFr
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Post by KanedaFr » Thu Dec 19, 2013 1:42 am

so it's just awesome !!!!!!! ;)

Teancum
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Post by Teancum » Tue Jun 24, 2014 9:22 pm

EDIT: Whoops announcement thread here
viewtopic.php?t=1777&postdays=0&postord ... 9608933551

Not sure if Prophet36 just missed this thread but he's had an update.

"Some of you may find this of interest, it's a project I've been working on intermittently for several years, to build a 100% open-source (hardware & software) development cartridge for the MegaDrive/Genesis, and it's now pretty much finished. The code and VHDL is all LGPLv3, and the PCB is CERN OHLv1.2. With a bit of patience and a decent soldering iron you can make one for about $40.

Here are some videos I made about it:

https://www.youtube.com/watch?v=mEH7a-a8dvQ
https://www.youtube.com/watch?v=JxBzxhMhANI
https://www.youtube.com/watch?v=dLoudQc8L08

...and the Hackaday write-up:

http://hackaday.com/2014/06/18/the-s...omment-1579271
http://hackaday.io/project/1507-USB-MegaDrive-DevKit

The cartridge has an FPGA, an SDRAM chip, an SD-card slot and a fast USB interface. It's able to setup a proxy for the GDB remote serial protocol, so you can build code using GCC, and source-level debug it using GDB just as you would with code running locally: set breakpoints, single-step through the code, examine memory and registers, etc.

The GDB link makes use of the fact that the SDRAM is fast enough to interleave accesses by the MegaDrive with access by the PC: a small machine-code monitor runs on the MegaDrive and uses a reserved area of the SDRAM to implement an arbitrary RPC mechanism using a semaphore to orchestrate message-passing.

The USB link is fast enough to implement a 100% nonintrusive bus-cycle tracer, so details of every memory read or write that the machine executes along with a 20ns-resolution timestamp is sent back over USB and written direct to disk. The length of the trace-log is limited only by your hard disk; a typical 2TB drive will allow you to trace execution for more than 24 hours! Perfect for finding out what was happening just before that intermittent bug in your latest blockbuster MegaDrive game! :-)

The cart can also be used standalone (i.e no USB connection to a PC), whereupon it boots into a menu program that displays a list of all the games on the SD-card and allows you to select one using the control-pad.

Unfortunately I don't have any of them to sell, but the designs are all open-source so you can make one yourself if you wish. If you're not too good with a soldering-iron you could pay someone else to do it for you. I'd also be very happy if someone decided to make a few of them and sell them (no royalties required!). "

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