Search found 445 matches

by Joe
Mon Feb 15, 2021 4:44 pm
Forum: NES Hardware and Flash Equipment
Topic: What it would take to build a repro of Akira for the NES
Replies: 1
Views: 733

Re: What it would take to build a repro of Akira for the NES

The TC0190 is simpler than the MMC3, and there are already repro boards using CPLDs to implement the MMC3, so it's certainly not more difficult. I'm not so sure about the final price. I see vendors selling flashable MMC3 boards for less than $25 (USD) each, but MMC3 is very popular so they could be ...
by Joe
Sun Feb 14, 2021 11:56 pm
Forum: NES Hardware and Flash Equipment
Topic: Mapper 30, but with more PRG ROM?
Replies: 14
Views: 1396

Re: Mapper 30, but with more PRG ROM?

Maybe a better plan is to borrow a page from Family Noraebang and have one latch and one external SIP resistor array to implement the UNROM-style banking. Huh! Yeah, that's exactly what I was trying to describe. You'd need a separate latch for CHR banking and mirroring control and whatever else sin...
by Joe
Sun Feb 14, 2021 7:53 pm
Forum: NES Hardware and Flash Equipment
Topic: Mapper 30, but with more PRG ROM?
Replies: 14
Views: 1396

Re: Mapper 30, but with more PRG ROM?

maybe a 16V8. Would it make sense to use a 16V8 mostly to drive chip selects and have one or two latches hold the mapper's state? Would it make sense to drive the ROM's upper address lines with a tristate-output latch and pull-up resistors to make the fixed bank? From what I've seen, you can get a ...
by Joe
Thu Jan 14, 2021 1:27 pm
Forum: NES Hardware and Flash Equipment
Topic: FDS and $4018/$4019/$401E
Replies: 4
Views: 2268

Re: FDS and $4018/$4019/$401E

Whatever it was, it had a keyboard. It uses HJKL as one set of arrow keys and ;/@] as another.

Code: Select all

$0B = CTRL+K = up
$0C = CTRL+L = right
$0A = CTRL+J = down
$08 = CTRL+H = left

$40 = @ = up
$5D = ] = right
$2F = / = down
$3B = ; = left
by Joe
Wed Dec 02, 2020 11:00 am
Forum: NES Graphics
Topic: Lossy compression for NES screens
Replies: 20
Views: 22194

Re: Lossy compression for NES screens

The first post in this thread already contains a link to the source, and it's the artist's Twitter account instead of a reupload on an image gallery...
by Joe
Wed Nov 25, 2020 4:07 pm
Forum: Other Retro Dev
Topic: DOS VGA Tricks
Replies: 37
Views: 11035

Re: DOS VGA Tricks

Importantly, the 16-scanline-high characters are almost always drawn for 9 columns in each character cell, and uses the VGA (and MDA)'s special stretching rules to fill a 9-pixel-wide character cell from 8 bits of data. VGA had separate 8x8, 8x14, 9x14, 8x16, and 9x16 fonts, although only a handful...
by Joe
Tue Nov 24, 2020 4:19 pm
Forum: Other Retro Dev
Topic: DOS VGA Tricks
Replies: 37
Views: 11035

Re: DOS VGA Tricks

Once your CPU is fast enough to copy the whole screen in vblank, there's less and less point to using hardware scrolling. The optimization of using hardware scrolling to limit your needed updates becomes very unnecessary. Even for Keen, the stuff it was doing only really helped the game play more s...
by Joe
Tue Sep 26, 2017 9:47 am
Forum: General Stuff
Topic: Is it possible to program Raspberry Pi in assembly?
Replies: 91
Views: 19507

Re: Is it possible to program Raspberry Pi in assembly?

Honestly I'm not sure which of these methods is better in practice, though. asm being more error prone and ugly, and __asm being less customizable? You're already optimizing "by hand" in either case, so whatever missed opportunity for optimizing code around the block I guess could be addressed by e...
by Joe
Mon Sep 25, 2017 11:46 am
Forum: General Stuff
Topic: Is it possible to program Raspberry Pi in assembly?
Replies: 91
Views: 19507

Re: Is it possible to program Raspberry Pi in assembly?

I've never heard of the optimizer doing anything inside inline assembly code. ?? That's actually the point of using inline assembly: to get exactly the code you specified. Volatile applies to C, not inline assembly. The optimizer can't change the inline assembly code, but it can change where and wh...
by Joe
Sun Sep 24, 2017 7:24 am
Forum: General Stuff
Topic: Is it possible to program Raspberry Pi in assembly?
Replies: 91
Views: 19507

Re: Is it possible to program Raspberry Pi in assembly?

Maybe this is naive, but wouldn't it be possible to just make a program like this? [...] And then link your assembly code in? That's possible; so is implementing main() entirely in assembly. You could write an entire C program without writing a single line of C code. Your main() function will be ca...
by Joe
Sat Sep 23, 2017 6:31 am
Forum: General Stuff
Topic: Is it possible to program Raspberry Pi in assembly?
Replies: 91
Views: 19507

Re: Is it possible to program Raspberry Pi in assembly?

What I meant is that, when I started programming in C I was tricked into thinking that if I wrote programs a certain way it made them optimized, when it fact I couldn't be further from the truth. It's still true, but compilers nowadays are smart enough to see the easy ones like ++i; versus i += 1; ...
by Joe
Tue Sep 05, 2017 5:31 am
Forum: General Stuff
Topic: The insanely low cost of relatively old computer parts
Replies: 23
Views: 7186

Re: The insanely low cost of relatively old computer parts

But does the chipset run at byte address granuarity? I thought with a 32-bit RAM word size, the address lines would be A33-A2, allowing 8 GB, not A31-A0. I'm talking about the address lines between the CPU and chipset, not between the chipset and RAM. Though now that you mention it, the CPU itself ...
by Joe
Mon Sep 04, 2017 10:08 am
Forum: General Stuff
Topic: The insanely low cost of relatively old computer parts
Replies: 23
Views: 7186

Re: The insanely low cost of relatively old computer parts

Yeah, I now see that I got that number from someone who didn't know what they were talking about (checking the number in a 32 bit operating system, not the menu in the BIOS). I did see that the computer should actually take 8GB of RAM, with I think a maximum of 2GB per slot, not that I would do it ...
by Joe
Sun Jul 30, 2017 1:54 pm
Forum: NES Graphics
Topic: NES emulator with 480i 30fps support?
Replies: 18
Views: 10438

Re: NES emulator with 480i 30fps support?

I only really want a 30fps weave because that's the only one I've noticed HDTVs doing with 240p composite. My TV changes methods depending on the video. With no background scrolling, the TV's heuristic decides that the video was converted from 30p and matches pairs of fields to produce 30 frames pe...