Search found 27 matches

by Enforcer
Wed May 15, 2019 4:51 am
Forum: Megadrive/Genesis
Topic: I'm officially building a microcode-level 68000 core
Replies: 43
Views: 6160

Re: I'm officially building a microcode-level 68000 core

Looking forward to your work, Nemesis. I’m actually going to be starting on my own 68K HDL project for a personal project. If I find anything I’ll let you know. I’ve tinkered with the idea of taking the schematic you’ve posted and the text description of it and writing an program that searches for l...
by Enforcer
Fri Apr 12, 2019 4:03 pm
Forum: Megadrive/Genesis
Topic: 8BitDo 2.4G controller
Replies: 3
Views: 1234

Re: 8BitDo 2.4G controller

And stay far away from the BT variant unless you really need BT.
by Enforcer
Sat Feb 23, 2019 7:28 am
Forum: Megadrive/Genesis
Topic: Bus Arbiter and IO Chip Access
Replies: 28
Views: 5589

Re: Bus Arbiter and IO Chip Access

You’re welcome. Your site has been immeasurably useful in my reversing efforts. I’m slowly working on the 5309 and 5308 chips as my day job has picked up. I’ve recently come into owning a high powered metallurgical microscope that I’m looking to make capable of scanning ICs. If I manage to get some ...
by Enforcer
Sat Dec 01, 2018 2:21 am
Forum: Exodus
Topic: Genesis 68K bus timing
Replies: 6
Views: 1626

Re: Genesis 68K bus timing

Me too, if it’s not to much trouble.
by Enforcer
Tue Nov 27, 2018 2:07 pm
Forum: Megadrive/Genesis
Topic: Looping access from 68K and Z80
Replies: 25
Views: 4122

Re: Looping access from 68K and Z80

Ordered last week and got them last night. https://www.questcomp.com/part/4/315-5313A-01/432898428
by Enforcer
Tue Nov 27, 2018 4:54 am
Forum: Megadrive/Genesis
Topic: Looping access from 68K and Z80
Replies: 25
Views: 4122

Re: Looping access from 68K and Z80

That’s pretty cool about reversing the 5313. How does one get involved with that? Also, I got all my chips from quest components. They all look to be in perfect shape. I was surprised at how well packaged it all came.
by Enforcer
Tue Nov 20, 2018 3:56 pm
Forum: Megadrive/Genesis
Topic: Looping access from 68K and Z80
Replies: 25
Views: 4122

Re: Looping access from 68K and Z80

https://www.questcomp.com Is who I went through since they didn’t require a quoting process. The other one I’ve seen was New York Semi.
by Enforcer
Tue Nov 20, 2018 6:41 am
Forum: Megadrive/Genesis
Topic: Looping access from 68K and Z80
Replies: 25
Views: 4122

Re: Looping access from 68K and Z80

My breakout boards cam it but sadly the pads for the pins on the chip were just a tad too short. New boards ordered but with the US holiday coming up it’ll be 10-14 days before I get them back. In the meantime, I found a semiconductor seller that had some genesis chips in stock so I picked up a coup...
by Enforcer
Sat Nov 17, 2018 4:56 am
Forum: Megadrive/Genesis
Topic: Looping access from 68K and Z80
Replies: 25
Views: 4122

Re: Looping access from 68K and Z80

I've removed the Bus Arbiter chip from my VA3. I'm waiting on a breakout board I made to show up. It got lost in the mail. I'll post any results I get once its up and running.
by Enforcer
Tue Nov 13, 2018 1:35 am
Forum: Megadrive/Genesis
Topic: Looping access from 68K and Z80
Replies: 25
Views: 4122

Re: Looping access from 68K and Z80

I believe trying that will lock up the system. I currently have some breakout boards on order and will be documenting the behavior of th IO and Bus Arbiter chips in the next few weeks.
by Enforcer
Mon Oct 15, 2018 9:04 pm
Forum: Megadrive/Genesis
Topic: Bus Arbiter and IO Chip Access
Replies: 28
Views: 5589

Re: Bus Arbiter and IO Chip Access

That makes more sense. Thanks! I’m no where near looking into VDP stuff just yet so I’m sure there will be a ton of rediscoveries.
by Enforcer
Mon Oct 15, 2018 6:54 pm
Forum: Megadrive/Genesis
Topic: Bus Arbiter and IO Chip Access
Replies: 28
Views: 5589

Re: Bus Arbiter and IO Chip Access

(that thread was actually one of the first I think where VDP signals behavior was deeply studied, too bad most of the image links are broken now) It's pity, yes. Feel free to ask me to recapture any of it (or any other) with any of this method: oscilloscope with up to 4 channels (up to 100MHz throu...
by Enforcer
Mon Oct 15, 2018 4:55 pm
Forum: Megadrive/Genesis
Topic: Bus Arbiter and IO Chip Access
Replies: 28
Views: 5589

Re: Bus Arbiter and IO Chip Access

I know someone who did a pinout of the VA0 EDCLK circuit. I’m asking them for a copy and will run it through a circuit simulator. If anyone knows of a good free simulator with 74LS series parts, let me know. I’ll have to see if our Cadence package has them.
by Enforcer
Mon Oct 15, 2018 1:03 pm
Forum: Megadrive/Genesis
Topic: Bus Arbiter and IO Chip Access
Replies: 28
Views: 5589

Re: Bus Arbiter and IO Chip Access

I agree most of the interactions I did with regards to !BGACK should be impossible. I was doing them more to see if it would give more info on how the functionality was implemented at a logic level. I did test with the other signals left asserted when !SRES becomes asserted. With a valid clock it al...
by Enforcer
Mon Oct 15, 2018 4:46 am
Forum: Megadrive/Genesis
Topic: Bus Arbiter and IO Chip Access
Replies: 28
Views: 5589

Re: Bus Arbiter and IO Chip Access

After a bunch of trial and error, and going through every single input in a binary fashion, I think I have a description of how the 315-5345 works. 315-5345 Behaviors EDCLK (9), !EOE (10), IA14 (11) and !NOE(12) are outputs. !BGACK (1), !HSYNC (2), !SRES (3), A14 (4), !M3 (5), !OE0 (6) , MCLK (7) , ...