Search found 488 matches

by Jarhmander
Tue Mar 31, 2020 8:27 pm
Forum: Newbie Help Center
Topic: Bit reversing
Replies: 7
Views: 338

Re: Bit reversing

Let's not forget that bit reversing the frame counter can be useful to allow subpixel velocities without having to store the subpixel position, as explained here.
by Jarhmander
Tue Feb 04, 2020 7:30 pm
Forum: Newbie Help Center
Topic: 8x16 and whatever else unreg wants to know
Replies: 1557
Views: 404591

Re: 8x16 and whatever else unreg wants to know

Thus I won't go into detail about it. So much for completeness... I honestly have no idea what you're referring to, so I can't even research on my own. Don't worry, he's just talking about the SO (set overflow) pin that exists on the stock 6502. It's most known as one obscure feature the C64 CBM dr...
by Jarhmander
Sun Jan 26, 2020 8:21 am
Forum: NESdev
Topic: Undesired Jail bars on French NES and checkerboard pattern
Replies: 45
Views: 14644

Re: Undesired Jail bars on French NES and checkerboard pattern

lidnariq wrote:
Sat Jan 25, 2020 12:34 pm
What does the 26,06 mhz crystal on the nes motherboard do?
"Everything".
Image
by Jarhmander
Wed Dec 25, 2019 1:13 pm
Forum: General Stuff
Topic: Chuck Peddle (1937-11-25–2019-12-15)
Replies: 2
Views: 2744

Chuck Peddle (1937-11-25–2019-12-15)

Recently, Chuck Ingerham Peddle, one of the main designer of the 6502, passed away. While he isn't with us anymore, the 6502 and all it enabled at the time (the NES, the Commodore 64, the Atari 2600, the Apple II and a myriad of other computers and video game consoles) will remain forever as a impor...
by Jarhmander
Sun Apr 21, 2019 5:35 am
Forum: NESdev
Topic: Way to manage spawning points
Replies: 9
Views: 6875

Re: Way to manage spawning points

Different object types, such as moving platforms, like you mentioned, may need different properties, and I handle that by giving each object in the object definition table a "parameter" byte. If 8 bits are enough to represent an object's type's attributes, great, if not, those 8 bits are used to in...
by Jarhmander
Tue Mar 26, 2019 5:45 am
Forum: NES Music
Topic: APU: volume and... envelope? ^^;;;
Replies: 35
Views: 24227

Re: APU: volume and... envelope? ^^;;;

Some Sunsoft games used short triangle bursts like za909 posted. The croaking frogs in Gimmick!, or some sound effects in Fester's Quest, etc. I think Metroid also used it for the "bubble" sound in the Tourian area music. It's not very common, though. Famitracker never supported it (though I dunno ...
by Jarhmander
Wed Mar 20, 2019 5:22 am
Forum: NES Hardware and Flash Equipment
Topic: Verified RP2A03 Verilog/VHDL core?
Replies: 3
Views: 6483

Re: Verified RP2A03 Verilog/VHDL core?

tepples wrote:
bytestorm wrote:Is there any good softcore around of the RP2A03?
I can think of Bubble Bath Babes, Hot Slots, and Peek-A-Boo Poker.
Oh you, tepples. I actually giggled at that one. Good one!
by Jarhmander
Sun Mar 10, 2019 7:38 am
Forum: NESdev
Topic: Create a 256x192 bitmap mode in C?
Replies: 14
Views: 6982

Re: Create a 256x192 bitmap mode in C?

You need 2 background palettes: Color 00: black; Color 01: white; Color 10: black; Color 11: black; Color 00: black; Color 01: black; Color 10: white; Color 11: white; The first palette honors bit 0 of the color index and ignores bit 1, the second palette honors bit 1 and ignores bit 0. This allows...
by Jarhmander
Thu Feb 07, 2019 5:10 pm
Forum: General Stuff
Topic: The Difficulty of ARM Assembly
Replies: 57
Views: 24940

Re: The Difficulty of ARM Assembly

... and that's essentially what a Global Offset Table (GOT) is.
by Jarhmander
Sun Feb 03, 2019 9:31 am
Forum: General Stuff
Topic: The Difficulty of ARM Assembly
Replies: 57
Views: 24940

Re: The Difficulty of ARM Assembly

ARMv6-M (the core of Cortex-M0) is a bastardization; it's a stripped down, not very orthogonal copy of ARMv7-M (Cortex-M3). For instance, on the ARMv6-M, much of the instructions can only act on r0-r7, and the destination is forced to be the same than one of the operand —very few instructions can us...
by Jarhmander
Sun Jan 27, 2019 12:00 pm
Forum: Other Retro Dev
Topic: AMT630A firmware for mini TFT screens
Replies: 47
Views: 68713

Re: AMT630A firmware for mini TFT screens

With a ST Nucleo board and STLink utility, you could do an SPI flash programmer fairly easily. STLink utility comes with "external loaders", which can be used to flash external memories connected to a ST mcu. You can thus wire up a Nucleo to the SPI Flash, and then use an external loader that works ...
by Jarhmander
Fri Jan 25, 2019 11:56 pm
Forum: GBDev
Topic: Vaus-like controller planned for Alleyway?
Replies: 8
Views: 7442

Re: Vaus-like controller planned for Alleyway?

16bit report? That's... intense. Like, sure, the ADC in the controller is probably 10 bits in resolution, but 7 bits would be sufficient, right?
by Jarhmander
Thu Jan 24, 2019 10:54 pm
Forum: GBDev
Topic: Vaus-like controller planned for Alleyway?
Replies: 8
Views: 7442

Vaus-like controller planned for Alleyway?

Two days ago, I attended a meetup of C++ Montréal. The presentation was about the presenter's (Frédéric Hamel) attempt to make a fairly accurate Gameboy (DMG) emulator in C++11. I have to say, it's quite a strange feeling to hear about things and people you only saw in the internet, never in the "re...
by Jarhmander
Wed Jan 02, 2019 8:28 am
Forum: Newbie Help Center
Topic: How to do math with values that wrap around at 240? (scroll)
Replies: 11
Views: 3780

Re: How to do math with values that wrap around at 240? (scr

Happy New Year everyone!
tepples wrote:The only restriction on the scroll position in VRAM space and world space is that their difference has to be a multiple of 16. Allowing them to become unaligned recently bit me.
Care to say what kind of issue it causes? I'm curious, because I can't figure out the problem.
by Jarhmander
Sun Dec 30, 2018 12:18 pm
Forum: Newbie Help Center
Topic: Load Background loop
Replies: 5
Views: 2946

Re: Load Background loop

Are you familiar with the various indirect addressing mode? That's because you will need to deal with 16-bit quantities, and indexed addressing won't cut it, because it can only be used with 8-bit indexes. There are several ways to do this, but essentially, you need to put a pointer in zero page, ha...