Bootloader PC Side

For hardware talk only (please avoid ROM dumper stuff)
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Munkyears
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Bootloader PC Side

Post by Munkyears » Tue Feb 02, 2010 3:28 pm

Anyone have a copy of the bootloader written for Rs-232 connection to the d-sub on the back of the megadrive from what i remember, you can launch roms straight to it. I know there are talk of flash carts but i want to do it the old fashioned way

Many thanks
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Munkyears
Very interested
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Joined: Sat Mar 21, 2009 4:24 pm
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Post by Munkyears » Tue Feb 02, 2010 3:30 pm

I also have the pin out for it, if its any use. i just need to burn this bootloader onto an eprom soldering it to a cart.

Many thanks. P.s yeah i know how slow it is at sending it but will save me the hassle and money of a flash cart
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TmEE co.(TM)
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Post by TmEE co.(TM) » Tue Feb 02, 2010 3:41 pm

The port on the back is a 3rd contorller port with reversed gender.... unless you have a bootloader running on MD side, you will not get any kind of ROMs running... you can only run special ROMs that are less than 64KB in size, since there's not more RAM in MD.
And those ROMs you write yourself...
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Mask of Destiny
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Post by Mask of Destiny » Tue Feb 02, 2010 4:35 pm

TmEE co.(TM) wrote:The port on the back is a 3rd contorller port with reversed gender.... unless you have a bootloader running on MD side, you will not get any kind of ROMs running... you can only run special ROMs that are less than 64KB in size, since there's not more RAM in MD.
And those ROMs you write yourself...
Sounds like he is planning on wiring up a simple EPROM cart to boot the MD. He probably doesn't feel like erasing and burning the EPROM every time he wants to test something.

I don't have any code to use the serial mode, but I do have code that transfers data using a 4-bit parallel protocol. It's a lot faster than using the serial mode, but has the disadvantage of requiring the CPU to poll a register during transfers rather than using interrupts.

None of the code was directly published, but if you download the ZIP from here: http://www.retrodev.com/transfer.html and peek at the files inside the ISO image you'll find the source to the Megadrive side. The source to the PC side is lost unfortunately.

I started rewriting this software a while back with a modified version of the protocol. I can send you or post the source to that if you like for both sides.

In both cases, the code is setup to use controller port 2 rather than the 3rd rear port (my Genesis doesn't have one) and is intended to be run from RAM on the Sega CD, but changing those for your purposes should be relatively minor.

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