Post by NetSamurai on Dec 6, 2004 5:20:13 GMT -5
OK, as of now, I have located all vias for:
Data bus
Address Bus
Vcc
Vdd
CE
The WE can be taken from the RAM (Actually, I think it is going into the ROM too...odd. Will have to verify this tomorrow)
Some of the vias were under the blob, but accessible from the bottom of the board.
I will adjust my labeled photo to work from the bottom of the board for clarity.
Almost there. I need to buy some more 30 AWG wire tomorrow so that I can wire it up to a header that will allow me to plug it into a programmer. I think I will probably build this: www.zws.com/products/epromr2/epromr_stage1.html since I do not have a programmer at the moment.
If the Kernel, Basic, and Character roms are located in this blob in a contiguous manner, we may be able to create a simple address decoder to allow accesses into the ROM for those, but all other accesses go to our flash rom.
Here's what's left:
1. Verify my via locations
2. Build a header
3. Check active levels of the CE and WE
(and other control pins if I locate more)
4. Read the ROM out
5. Determine the filesystem/layout
6. Locate the Kernel, Basic, Char ROM, or other
firmware in the dump
7. Build an address decoder and flash ROM board
8. Test it out
9. Having Fun!
Did I leave anything out? Anybody planning to help? I could use somebody that has more experience with decoding the binary dump, figuring out the filesystem,
and/or someone with a programmer already.
If everything goes according to plan, we should be able to use a compactflash in 8 bit memory mapped mode. It may require that we use an image generating program to burn the compactflash each time, but I'll cross that bridge when I come to it.
Finally, I have been eyeing the video and audio portions of the circuit (just a quick look really) and it looks like we *might* have S-Video there, or at least be able to
derive it from what's there. Again, just a quick visual trace of the circuit, so I could be completely wrong, but it looks like a ladder DAC (typical digital video interface.)
I have an oscilloscope, so I will likely be able to verify this once it takes priority.
Scott McDonnell
Data bus
Address Bus
Vcc
Vdd
CE
The WE can be taken from the RAM (Actually, I think it is going into the ROM too...odd. Will have to verify this tomorrow)
Some of the vias were under the blob, but accessible from the bottom of the board.
I will adjust my labeled photo to work from the bottom of the board for clarity.
Almost there. I need to buy some more 30 AWG wire tomorrow so that I can wire it up to a header that will allow me to plug it into a programmer. I think I will probably build this: www.zws.com/products/epromr2/epromr_stage1.html since I do not have a programmer at the moment.
If the Kernel, Basic, and Character roms are located in this blob in a contiguous manner, we may be able to create a simple address decoder to allow accesses into the ROM for those, but all other accesses go to our flash rom.
Here's what's left:
1. Verify my via locations
2. Build a header
3. Check active levels of the CE and WE
(and other control pins if I locate more)
4. Read the ROM out
5. Determine the filesystem/layout
6. Locate the Kernel, Basic, Char ROM, or other
firmware in the dump
7. Build an address decoder and flash ROM board
8. Test it out
9. Having Fun!
Did I leave anything out? Anybody planning to help? I could use somebody that has more experience with decoding the binary dump, figuring out the filesystem,
and/or someone with a programmer already.
If everything goes according to plan, we should be able to use a compactflash in 8 bit memory mapped mode. It may require that we use an image generating program to burn the compactflash each time, but I'll cross that bridge when I come to it.
Finally, I have been eyeing the video and audio portions of the circuit (just a quick look really) and it looks like we *might* have S-Video there, or at least be able to
derive it from what's there. Again, just a quick visual trace of the circuit, so I could be completely wrong, but it looks like a ladder DAC (typical digital video interface.)
I have an oscilloscope, so I will likely be able to verify this once it takes priority.
Scott McDonnell