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DCXfer
We created the "Xfer" 1.56MBPS card. The card was extremely popular, many "famous" names in the DC scene bought them - we even sold a couple to Sega themselves!
PLEASE NOTE:
We do NOT have either the Katana or WindowsCE devkits for the DC,
ALL the software that will appear on this site will NOT require them.
All information is being gathered through reverse-engineering the console.
Any disc images or programs on this website will NOT require you to have any official devkit or the Utopia Boot CD.
The card:
Two different types of card were made:
DCXfer card, this actual card was bought by "Thomas Franz". |
DCXferPro card, this actual card was bought by "Brian Peek". |
Features:
* There are no complicated MAXIM chips to find or connect to!
* You do NOT have to modify your dreamcast in order for this devcard to work.
* This card can TX and RX at the fastest speed the DC serial ports can go.
* Uses normally unused PC memory locations (com port 8)
* ISA card
* NOT automatically detected and messed with by Windoze! ;)
* Uses NO interrupt or DMA resources on the PC!!!
* Concurrent transfer at full speed possible!
* Pro card has two 1/56MBPS ports for developing on two machines at the same time!
With this card Dan's 'Stars' demo in original 750kbyte+ SREC format transfers in about 5 seconds or less!
(Using the normal serial devkit this takes 2 mins 20 seconds!)
Make your own card:
Important notice: We will not be responsible for any damage to you, your PC, or your Dreamcast!
You need to:
Buy a serial card that has a real 16C650 on it (not a compatible).
The card also needs to have a GD75232 or compatible (near the serial port).
To be fully compatible it also needs to be able to allow you to select Com8/$268, interrupts are not used.
We found cards that are marked "4022 Ultra RS-232" the easiest to modify.
Instructions:
16C650 cards have a 7.3728Mhz crystal on them (its a square silver thing with 4 pins on the bottom), remove this and replace it with a 25Mhz crystal.
Be careful not to damage the board. The GD75232 needs to be removed (its a chip thats near the serial port, it has 20 pins).
You will not need the GD75232 again, so don't worry about damaging it, your main concern is the board.
After GD75232 has been removed you need to connect some wires where the chip was, connect:
2 to 19, 3 to 18, 4 to 17, 5 to 16, 6 to 15, 7 to 14, 8 to 13, 9 to 12
Whatever you do, do NOT connect 1 to 20 and/or 10 to 11!!!
Disconnect any jumpers for interrupts, they are not used.
Make sure that the clock divider on the board is set so the crystal goes straight to the 16C650 (just make it so the board is in its fastest configuration).
Configure the port address jumpers to COM8 which is address $268...
CHECK ALL YOUR WORK TWICE BEFORE PLUGGING IN AND SWITCHING ON!!!
The 16C650 is only supposed to be driven a max rate of 24Mhz, we are driving it at 25Mhz (its being overclocked).
After its been on for a while check that the 16C650 isn't getting too hot.
If it is then fit some kind of heatsink.
DO NOT USE THE CARD FOR ANYTHING OTHER SERIAL COMMS AFTER THE MODIFICATION!!!
Transfer lead:
To us the card you first have to make a transfer lead (a "soopadoopa" lead!) using an original NEOGEO to Dreamcast lead.
The circuit:
James Dexter's Smokin' "Do It Yourself" lead tutorial:
We recommend that you follow James' pictures as it looks like the best way to build the cable...
Introduction:This is me, James Dexter... *NOT* smokin' after making my lead and getting my "Xfer" card! :) And yes - I am getting sponsored by a "leading" fabric conditioning manufacturer!  DIY tutorial, part 1/3These are the 110 ohm resistors (from pins con1-5 and con1-3) that go to 5v (con2-1)...  DIY tutorial, part 2/3This is the addition of the 1k resistors (from pins con1-2 and con1-6) that go to ground (con1-4)...  DIY tutorial, part 3/3This is the inline pair of diodes that use the black and green wires (pins con1-2 and con1-6)! The hard bit has been done, the rest is up to you! ;)  Anthony's prototype DC lead!!!He always builds things like this and they tend to work!!! :( Look at the old maxim chip he keeps there "just in case"!!! 
Note: You know the cable works when dcexe makes the borders go green.
Although all cards are tested at 1.562MBPS before shipping, some batches of DC in combination with some of the chips on the card and DC->NEO boxes may have problems in the fastest speed.
This occurs when transfering data from DC to PC, if you have problems use the dcexe /n1 switch to slow the card down to 781kbps.
Experimenting with changing the resistance of the 110 ohm resistors can usually resolve the problem...
If you have the pro card then you may experience one set of resistor values working with one port, but not the other.
In practice, port one is better linked to the dc with the 110 ohm resistors, but port 2 usually may need different values for full speed from the dc to the pc.
For Example: Thomas Franz was one of the people who had problems with the 110 ohm resistance, he achieved full speed by using variable resistors; setting 125 ohm on the white wire and 118 ohms on the blue...
The DCExe utility:
This really consists of two programs one for the PC and one for the DreamCast! But you don't notice, because the latest DC program is "built-in" to the PC program and uploaded if needed.
Download V1.010 of DCExe here.
Features:
* Written in PC assembly language for size and speed
* Works with the "Pro" card
* Sends new loader to the now 'standard' marcus serial slave, then maxi's to 1.56mbps!
* Contains latest 'DC side' loader written in SH4 assembly language for size and speed!
* New 'Console' mode with more functions than standard Serial Slave software (memory dump, etc)
* Can transfer either SRECords or Binary files
* SRECord transfer acceleration
* Initial negotiation speed is 781kbaud, this allows easier testing of the resistor values
* Now supports Win95+ long filenames in the parameter!
When downloaded, the DCExe "console mode" normally has a green border, transfering to or from the DC will result in border colour changes (like an old Sinclair Spectrum loading!), this is normal! :)
PC side parameters:
Usage: DCEXE [/?] [/n#] [/c] [/b[#]] [/g[#]] [/2] [/3] [/s] [filename]
/?- Display usage
/n# - Set DC's 'N' to # (#=0 to 255)
/b[#] - file is binary, download to $# (default is 8c010000)
/g[#] - run at address $# (default is 8c010000 or /b address)
/c - Enter console mode at end of transfer
/f - Enter FileServer mode at end of transfer (experimental)
/2 - Use port 2 (pro only)
/3 - Use Doomed's special edition card! ;)
/s - Slow mode (turn off SREC acceleration)
Files are normally sent as SRECords, unless the /b switch is used!!!
DC side console commands:
?- Display version
B@@ - Binary transfer to @, size@ (@=4 bytes)
G@ - Go address @
H - Help
M[#] - Memory dump (#=8 digit hex number)
R - Reset DC
Sx... - SRECord (only types 0, 3 and 7 are valid)
Windows NT and above
Because of the way that WinNT and above protect your PC from "bogus" memory accesses, you will have problems on these OS's unless you run this device driver sent to us by Brian Peek - Thanks Brian! :)
How to use FileServer Mode:
The FileServer is experimental, you may obtain strange results (if any results at all!).
The fileserver allows you to access PC facilities from the DC.
With the fileserver you can save and load data both to and from the PC at high speed!
You can also print to the PC keyboard and get keys from the keyboard.
To use the FileServer, first Tx the command byte from the DC - then invert it and Tx it again...
Parameters follow as below...
| Command # | Description | Parameters |
| 0 | No operation, is ignored! | None! |
| 1 | PutChar | Tx a byte to display. |
| 2 | GetChar | Rx a byte from pc (the pc waits for a keypress). |
| 3 | Open | Tx a string for the filename, then Tx a byte for the open mode. Rx two bytes for the file handle. |
| 4 | Create | Tx a string for the filename, then Tx two bytes for the create mode. Rx two bytes for the file handle. |
| 5 | Read | Tx two bytes for the handle, Tx four bytes for the length. Rx four bytes for a length, and then Rx "length" bytes, repeat until Rx "length" is zero. |
| 6 | Write | Tx two bytes for the handle, Tx four bytes for the length, and then Tx "length" bytes. |
| 7 | Seek | Tx two bytes for the handle, then Tx four bytes for the offset and finally Tx a byte for the mode. |
| 8 | Close | Tx two bytes for the handle. |
| 9 | Delete | Tx a string for the filename to delete! |
| 10 | Rename | Tx a string for the oldname, then Tx another string for the new name! |
| 11 | Exit | Makes the PC exit DCExe! |
| 12 | Write Blank | Tx two bytes for the handle, Tx four bytes for the length! |
There is *no* error handling within the FileServer.
Information for programmers who want to write new utilities for the DCXfer card:
You can easily write your own utilities for the DCXfer card.
Dreamcast side:
Just write 'N' to the SH4 baud rate divider 'N', if you want to know the exact baudrate it is "156200/(N+1)"
Download complete source code for the DC program here. You need this utility to insert any updates (serial.inc) into the PC side of the program.
PC Side:
You can use the SH4 DCExe (V1.002) SREC for DC as a test file to get your PC code to work.
The first thing it does it set 'N' to one this is 781kbaud, the 2nd fastest rate the DC supports!
It loads below the normal marcus' Serial Slave.
To help you start writing your own utilities you can download the complete source code for the DCExe program here.
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