Search found 211 matches

by teaguecl
Sun Aug 21, 2022 6:38 pm
Forum: NES Hardware and Flash Equipment
Topic: NES Repair
Replies: 3
Views: 917

NES Repair

I powered on x-mas '85 NES for the first time in years a few weeks ago and got nothing - not even a light on the power button. I opened it up and started probing voltages and very quickly found the 17805 was not only producing the wrong output - but it was burning hot. I purchased a replacement 7805...
by teaguecl
Mon Sep 04, 2017 10:05 am
Forum: NESemdev
Topic: nestest question - DCP Illegal opcode
Replies: 3
Views: 3840

Re: nestest question - DCP Illegal opcode

Thank you so much for the assistance. To stop nestest when it's done I simply put a breakpoint at C66E which seems to work fine. I am still seeing behavior that I can't understand - maybe I'm not using the test rom correctly? My emulator currently does not support opcode 0xE7 (ISB/ISC) and it will c...
by teaguecl
Sun Sep 03, 2017 11:18 pm
Forum: NESemdev
Topic: nestest question - DCP Illegal opcode
Replies: 3
Views: 3840

nestest question - DCP Illegal opcode

I'm having a tough time running nestest. If I just load it and run, it reports all OK on both sets of tests. However, if I force it to start at $C000 as the documentation indicates for automation - it crashes with an illegal opcode 0x32. I tried running it in Nintendulator and forcing it to start at...
by teaguecl
Sat Jun 22, 2013 8:50 pm
Forum: NES Hardware and Flash Equipment
Topic: Can RetroUSB's Ciclone be copied?
Replies: 9
Views: 3790

Re: Can RetroUSB's Ciclone be copied?

is there some way to copy the code off so I don't have to spend the $4 on a $0.50 chip? $4 is very reasonable. The PIC only costs $0.50, but they guy who did a many thousands of dollars worth of work on reverse engineering the CIC deserves a little as well. $4 is quite a bargain considering the equ...
by teaguecl
Mon Jun 17, 2013 10:58 pm
Forum: NES Hardware and Flash Equipment
Topic: HW Test Harness
Replies: 7
Views: 4810

Re: HW Test Harness

Mappers all work from the 72pin connector, why can't you? Yeah it'll be a little more work and you'll really have to know how the mappers work, but the package issues should be your smallest concern.' EDIT: to be a little more clear what I mean, generally all the mappers inputs connect to the 72/60...
by teaguecl
Mon Jun 17, 2013 6:59 pm
Forum: NES Hardware and Flash Equipment
Topic: HW Test Harness
Replies: 7
Views: 4810

Re: HW Test Harness

One thing to look out for: the most popular ASIC mappers were in surface mount packages, not DIP, so you'll need various converters to plug them into your harness. edit: Browsing through nescartdb, there are a significant number of infrequently-used 0.1" DIP ones: RAMBO-1 (m64), MIMC-1 (one of...
by teaguecl
Mon Jun 17, 2013 6:22 pm
Forum: NES Hardware and Flash Equipment
Topic: HW Test Harness
Replies: 7
Views: 4810

Re: HW Test Harness

MMC1 won't be useful for me (although probably will be for some people, so it might be worth it anyways), although if I get some FPGA then these hardware test might be useful to make Verilog Famicom (if I ever write this, it will be public domain, and the resistors/capacitors will be wired external...
by teaguecl
Mon Jun 17, 2013 5:04 pm
Forum: NES Hardware and Flash Equipment
Topic: HW Test Harness
Replies: 7
Views: 4810

HW Test Harness

I've been looking to do some more hardware projects, and I've always wanted to know EXACTLY how some of the devices work. I'm thinking of creating a test harness something like what Kevtris mentioned about a decade ago. Basically just a 40-pin ZIF connected to a bunch of IO. I was thinking a Arduino...
by teaguecl
Fri Jun 14, 2013 10:25 pm
Forum: NES Hardware and Flash Equipment
Topic: Pitch of cartridge pins connector discussion
Replies: 27
Views: 13646

Re: New hardware idea (USB and FamilyVM based)

I hate to bring up this thread again - let me start by saying I don't mean for the tone to be negative. I was thinking about doing a project this weekend, so I dug up my old connector from Digikey and double checked it. It in fact does not work. Below is a photo of a ruler, a Super Mario board, and ...
by teaguecl
Tue Mar 19, 2013 8:32 pm
Forum: NESemdev
Topic: Sprite 0 question
Replies: 6
Views: 3669

Sprite 0 question

I understand the timing and logic behind the Sprite 0 hit flag, but I don't understand how the PPU knows which sprite is the 0th one. Here's what (I think) happens in the PPU when rendering a sprite on scanline N. 1. User loads 256 bytes of sprite data into OAM via $4014. Obviously the first 4 bytes...
by teaguecl
Thu Mar 14, 2013 8:58 am
Forum: NESemdev
Topic: INC question - possible Nintendulator bug?
Replies: 14
Views: 5893

Re: INC question - possible Nintendulator bug?

Thank you! I couldn't sleep last night thinking about this issue - embarrassed that the answer is so obvious. Really appreciate the explanation of that one.
by teaguecl
Wed Mar 13, 2013 11:35 pm
Forum: NESemdev
Topic: INC question - possible Nintendulator bug?
Replies: 14
Views: 5893

Re: INC question - possible Nintendulator bug?

Thanks again for the help everyone, could someone explain this one to me as well? This trace from Nintendulator shows a BEQ instruction taking 9 PPU clocks (3 CPU clocks). I don't see how this is the case. To me it seems like this should take 4 CPU clocks. It should use the two standard cycles, plus...
by teaguecl
Wed Mar 13, 2013 9:43 am
Forum: NESemdev
Topic: INC question - possible Nintendulator bug?
Replies: 14
Views: 5893

Re: INC question - possible Nintendulator bug?

Thanks for the help everyone, I was just using inaccurate info.
by teaguecl
Wed Mar 13, 2013 9:03 am
Forum: NESemdev
Topic: INC question - possible Nintendulator bug?
Replies: 14
Views: 5893

INC question - possible Nintendulator bug?

I have been running Blargg's test roms through Nintendulator (much thanks to Blargg and Q for these!). Specfically, I am using this test from the instr_test suite: 01-implied.nes http://blargg.8bitalley.com/parodius/nes-tests/instr_test-v3.zip Fairly early on, this sequence occurs: E881 C8 INY A:00 ...
by teaguecl
Fri Mar 01, 2013 3:39 pm
Forum: NESemdev
Topic: Blargg's test roms
Replies: 5
Views: 4054

Blargg's test roms

I found Blargg's cpu test roms on the "Emulator Tests" page of the wiki - the test are at: http://blargg.8bitalley.com/parodius/nes-tests/instr_test-v3.zip I thought these would be perfect for testing my cpu core. I ran into a strange problem, was wondering if anyone could explain it to me...