Original post: http://8times8.host56.com/?p=334

I started porting the cartreader software to the eZ8 microcontroller. It is already possible to read cartridges.

Because the eZ8 has 29I/O pins I don't have to use latches to expand the address bus. This means I only need two IC's for the entire build: A max232 for serial communication and the microcontroller! This greatly reduces the cost of the entire thing. It also makes it much easier to build than its arduino counterpart.



The cartreader V2 has a renewed communication protocol. Instead of dividing the cartridge address range in pages you can have random access to the cartridge via the pc and do block transfers. Every block has a header like this:

mode = [0x00..0x01] (0x00=read, 0x01=write)
size = [0x00..0xFF] (0x00=1byte, 0xFF=256bytes)
addrH = [0x00..0x0F](12 bit start address)
addrL = [0x00..0xFF]
If write mode was selected [size] bytes will follow. These are buffered and then written to the cartridge starting at the 12 bit start address.

In the next couple of days I will modify the romclient.exe pc software so it works with the eZ8 version. I will rename it to romclient2.exe to avoid confusion.

indeed that pretty interesting. Block transfer is really cool 

I just succesfully modified the romclient.exe to work with the new block transfers. It works even better than before. I tested it with these games so far:
Demon Attack
Yar's Revenge
Video Pinball

The next thing I am going to implement is bankswitching. I am not sure how I want to do this yet though. I might create a simple interpreter for it. Example for an 8KB cartridge with 2 4k banks:
000[4k],sw[FF9],000[4k]Result:
Read 4Kbytes starting at 0x000
Bankswitch by putting address 0FF9 on the address bus
Read 4Kbytes starting at 0x000
This results in an 8KB file on the computer.

Oh also: my code assembles to 218 bytes.

I just uploaded an old video of the arduino version in action. I want to get one type of bankswitching to work today: F8. I described that method in my previous post. The cool thing about the new block transfer communication is that it allows for bankswitching to be controlled by the pc. No need to change any of the microcontroller's firmware.

I am also going to draw the schematics for the new cartreader.


Edit: I almost got the first bankswitching method to work. There is a little bit of glitching going on though. I might have to add some delay.
Edit2: After I modified the rom dump with a hex editor I got it to work. I fixed the bug that caused the dump file to have a 1 byte offset on every bank. This was because I did not read the byte returned from the bankswitching!

I managed to dump Asteroids which is an atari 8k game that uses F8 bankswitching!


Edit: I do not own any more F8 bankswitching games sadly, but I tested some other games now too:
Slot Racers
Combat
Pac-Man
Outlaw
Chopper Command
Megamania

Wow that's pretty awesome, great job !

Working on a better multicartridge as well. This one will support F8 bankswitching! There are three IC's in the cartridge that take care of the bankswitching. The cartridge will also feature a much larger RAM chip than the last one. This one has 128KB ram which can hold up to 16 8k games!

Cool stuff Keoni! I can't watch the video atm cause youtube is acting up. I'll check it again later.