October 16, 2019, 10:04:57 pm

Daydream ROM box kit

Started by pentium, September 15, 2008, 11:26:02 pm

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mikeboss

I also was in touch with one of the develpers about two and a half years ago. I live not too far away from their headquarters and one of the NeXT tagged cubes that was used to develop DayDream ended up being in my collection... just let me know if I can be of any help.
October 12, 1988 Computing Advances To The NeXT Level

barcher174

I'm waiting for some 15 pin connectors to arrive so I can make a passthrough and probe the I/O. I notice that you can only allocate 1MB less than the total system memory. My hope is that this accounts for both kernel and ROM overhead, meaning that everything is dumped to system memory before the mac OS boots. I think trying to make a 1-1 copy of the board is probably more effort than just emulating the hardware response. If I was designing something like this I would probably do the bare minimum to keep Apple happy about the licensing. With that in mind I think we've got a real shot at cloning this.

pentium

This is VERY promising. The chips add another piece to the puzzle. At this point the last major variable is the contents of the GAL.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

korneluk

Quote from: "barcher174"Good news, I've managed to get a part number off one of the remaining chips.




barcher174,
based on the pictures, here is a basic description of the circuit:
* two 74HC4040 ICs are counters used to generate the addresses.
* GAL16V8 and the 74HC151 are used for address decoding and chip select.
* the 8-pin IC is probably a timer used to generate the clock for the address counters.

I suspect all this circuit is doing is reading the ROMs into memory at power up.

I have access to a GAL programmer at work. If you send me the board, I can read the GAL, or, if it is protected, put a logic analyzer on the bus to finish reverse engineering the Daydream PCB.

regards,

-- jose k.

pentium

To help push this project along, I'll offer to pay shipping both ways between you and korneluk.

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

barcher174

Hi all

I have some more debug I want to do on my side, but if I'm unsuccessful I'll pass the ball along.

--
Brian

korneluk

Quote from: "barcher174"Hi all

I have some more debug I want to do on my side, but if I'm unsuccessful I'll pass the ball along.

--
Brian


Brian,
here's a little incentive: I have one of the DSP memory expansion boards for the Cube (the only one I have ever seen). Obviously another project that deserves a thread of its own, however, I am willing to loan it to anyone who can provide a Daydream board in exchange :)

-- jose k.

gtnicol

There are multiple versions of the DayDream... I assume they're all pretty much the same. I have another one or two here...

korneluk

Quote from: "gtnicol"There are multiple versions of the DayDream... I assume they're all pretty much the same. I have another one or two here...


gtnicol,
can you open the box and see if there are any identifying marking/part numbers on the 8-pin IC? I suspect it is a timer to provide a clock signal to the 74HC4040 counters, which in turn, output an address to the ROMs.
TYVM,
-- josé k.

gtnicol

My one is rev 1.34 and both those chips have been sanded to remove the identifier.

korneluk

Quote from: "gtnicol"My one is rev 1.34 and both those chips have been sanded to remove the identifier.


I have a basic schematic and I am in the process of wire-wrapping a prototype. I have a set of Mac ROMs, but need a DayDream board and cable to ohm out the the 15-pin cable to the 26-pin pin connector on the PCB.

Could I borrow one of yours?

-- josé k.

gtnicol

Should be able to able to do that. If you tell me what you need, I can throw an ohmeter on there too...

barcher174

As long as there are multiple people working on this, let me share what I know. The daydream is using the UART on the DSP port to communicate. I think the only reason the DSP port is used is the addition of 12V to power the device. Otherwise they probably would have just used a standard serial port. The pinout is as follows:

     Pin 1   SCK             Pin  9  GND
     Pin 2   SRD             Pin 10  GND
     Pin 3   STD             Pin 11  GND
     Pin 4   SCLK           Pin 12  SC2
--> Pin 5   RxD             Pin 13  SC1
--> Pin 6   TxD             Pin 14  SC0
--> Pin 7   +12V, .5A    Pin 15  GND
     Pin 8   -12V, .1A

The daydream appears to be a "dumb" device. As far as I can tell it waits for predetermined sequence from the daydream kernel over serial and then begins dumping the rom row by row to be read into memory. I have been exploring this handshake using a USB serial adapter as I documented in another thread. You can set a boot loop by using 'sd daydream' as your default boot device. When you do this you get a repeating pattern in a serial console. Example at 115200:

xx~x~xxx~xNxpx@x~x>xNxxpx0x@xx~x~~x>x>~xNxN~xx~xpxp~x0x0~x@x@~xxx~x~~x~~x~xx>x>~x>~x>xxNxN~xN~xNxxx~x~xxxpxp~xp~xpxx0x0~x0~x0xx@x@~x@~x@xxx~xxx~x~~x~~x~xx~x~cx~xx~`xx~x~xxxxcx|x`xfxf~xf~xfxxfxfgxf|xf`xx~x~xxxxcx|x`xxxx~xx~xxxxxxxcxxxxx`xx~x~xxxxcx|x`x`x`~x`~x`xx`x`cx`|x``xx~x~xxxxqxx8q8


It of course is not in ASCII, so I've been looking for a serial debugger I can use on the Mac (probably going to need to install windows). After I have the hex sequence to send to the device, I will hook up the device to a serial console and record the output. I'm pretty sure we then just need to feed this back when prompted by the daydream kernel. There is then no need to reverse engineer the actual hardware.

Anyone can replicate what I've done so far without the daydream hardware. If you're able to get the output from the next into a serial debugger, please contact me.


--
Brian

pentium

I double checked the photos of my old board and it seems it too had the 8 pin chip sanded off.



What chip numbers we can see however do match up. You can also see that pins 5, 6, and 7 are tied together on that little chip. I wonder what on earth it's doing...

-NeXT 68040 Cube with NS 3.3 and 64Mb ram

Rob Blessin Black Hole

Quote from: "barcher174"As long as there are multiple people working on this, let me share what I know. The daydream is using the UART on the DSP port to communicate. I think the only reason the DSP port is used is the addition of 12V to power the device. Otherwise they probably would have just used a standard serial port. The pinout is as follows:

     Pin 1   SCK             Pin  9  GND
     Pin 2   SRD             Pin 10  GND
     Pin 3   STD             Pin 11  GND
     Pin 4   SCLK           Pin 12  SC2
--> Pin 5   RxD             Pin 13  SC1
--> Pin 6   TxD             Pin 14  SC0
--> Pin 7   +12V, .5A    Pin 15  GND
     Pin 8   -12V, .1A

The daydream appears to be a "dumb" device. As far as I can tell it waits for predetermined sequence from the daydream kernel over serial and then begins dumping the rom row by row to be read into memory. I have been exploring this handshake using a USB serial adapter as I documented in another thread. You can set a boot loop by using 'sd daydream' as your default boot device. When you do this you get a repeating pattern in a serial console. Example at 115200:

xx~x~xxx~xNxpx@x~x>xNxxpx0x@xx~x~~x>x>~xNxN~xx~xpxp~x0x0~x@x@~xxx~x~~x~~x~xx>x>~x>~x>xxNxN~xN~xNxxx~x~xxxpxp~xp~xpxx0x0~x0~x0xx@x@~x@~x@xxx~xxx~x~~x~~x~xx~x~cx~xx~`xx~x~xxxxcx|x`xfxf~xf~xfxxfxfgxf|xf`xx~x~xxxxcx|x`xxxx~xx~xxxxxxxcxxxxx`xx~x~xxxxcx|x`x`x`~x`~x`xx`x`cx`|x``xx~x~xxxxqxx8q8


It of course is not in ASCII, so I've been looking for a serial debugger I can use on the Mac (probably going to need to install windows). After I have the hex sequence to send to the device, I will hook up the device to a serial console and record the output. I'm pretty sure we then just need to feed this back when prompted by the daydream kernel. There is then no need to reverse engineer the actual hardware.

Anyone can replicate what I've done so far without the daydream hardware. If you're able to get the output from the next into a serial debugger, please contact me.

Would this NeXT dev tool help its in the archives :http://www.nextcomputers.org/NeXTfiles/Software/NEXTSTEP/Developer/Tools/Gtools/HexEditor.README

Best regards Rob Blessin
--
Brian
Rob Blessin President computerpowwow ebay  sales@blackholeinc.com http://www.blackholeinc.com
303-741-9998 Serving the NeXT Community  since 2/9/93