Search found 186 matches

by Garth
Thu May 07, 2020 10:46 am
Forum: NESdev
Topic: Linear interpolation overtones
Replies: 10
Views: 2804

Re: Linear interpolation overtones

I think the legitimate purpose of the interpolation would be to remedy some aliasing trouble, at the expense of accepting some distortion. Is a better anti-alias filter an option? Up to 4th- or 5th-order is pretty easy with common parts, not needing precision capacitors. (Precision resistors are com...
by Garth
Tue May 05, 2020 11:49 am
Forum: Newbie Help Center
Topic: eeprom chips
Replies: 6
Views: 1991

Re: eeprom chips

I have found a lot of those chips on ebay Be careful! If they're coming from China, they're usually not what they say they are. We've been through this on the 6502.org forum. Recently there have been a lot of fake 6502's and 65c02's on eBay—fake in the sense that they're not the exact type, brand, ...
by Garth
Mon Apr 27, 2020 7:26 pm
Forum: Newbie Help Center
Topic: Questions on CLC/SEC and general NMI logic
Replies: 6
Views: 1551

Re: Questions on CLC/SEC and general NMI logic

The carry flag is always drawn into the ADC and SBC instructions. If you already know that a previous instruction left it the way you want it, then you can omit the CLC or SEC; but usually an addition or subtraction will require initializing it. (If it's a multi-byte addition or subtraction, only do...
by Garth
Sat Mar 28, 2020 1:53 pm
Forum: General Stuff
Topic: Simulated Processor Project similar to 6502
Replies: 2
Views: 7823

Re: Simulated Processor Project similar to 6502

The AnyCPU forum is an offshoot of the 6502.org forum which most of the members are also on, but AnyCPU is for, as its name says, any processor, and most discussion has been about designing one's own processor. Discussion is always courteous.
by Garth
Wed Feb 19, 2020 8:39 pm
Forum: NESdev
Topic: divide by 10
Replies: 4
Views: 2844

Re: divide by 10

This is Omegamatrix's, 17 bytes and 30 cycles, from viewtopic.php?f=2&t=11336 :

Code: Select all

  lsr
  sta  temp
  lsr
  adc  temp
  ror
  lsr
  lsr
  adc  temp
  ror
  adc  temp
  ror
  lsr
  lsr
by Garth
Thu Jan 09, 2020 6:04 pm
Forum: NESdev
Topic: Auditing your own code.
Replies: 9
Views: 5092

Re: Auditing your own code.

If your assembler's .lst (list) file output includes an alphabetized list of all the labels and how many times each label is referenced, you can see which ones never got used, and especially if they're not just local branch labels, remove (or comment-out) the particular routines.
by Garth
Sat Jan 04, 2020 5:12 pm
Forum: General Stuff
Topic: What code editor do you use?
Replies: 25
Views: 12661

Re: What code editor do you use?

I use the MultiEdit professional programmers' text editor, the last DOS version, with an absolutely astounding long, long list of really nice features and a manual that's a inch thick. Today all versions are for Windows only, unfortunately. Giving it stiff competition today is UltraEdit which is als...
by Garth
Fri Jan 03, 2020 10:58 pm
Forum: General Stuff
Topic: Multi-pass assembler questions
Replies: 7
Views: 4947

Re: Multi-pass assembler questions

I describe a couple of conditional-assembly situations where no number of passes will ever end the phase errors, or where dozens of passes may be required (which may be ok), at http://forum.6502.org/viewtopic.php?p=45897#p45897 . Those are unusual though. A solution for the first one might be to hav...
by Garth
Thu Dec 05, 2019 9:19 pm
Forum: Newbie Help Center
Topic: need help with 6502 assembly
Replies: 5
Views: 4087

Re: need help with 6502 assembly

Oziphantom wrote:
Fri Nov 22, 2019 3:21 am
Sadly Bombjack.org is down
Here's an archived version:
https://web.archive.org/web/20191024144 ... bjack.org/
by Garth
Wed Nov 20, 2019 2:03 am
Forum: phpBB Issues
Topic: What happened to the Nesdev phpBB theme?!?!
Replies: 79
Views: 30222

Re: What happened to the Nesdev phpBB theme?!?!

I suppose you could turn the monitor brightness down if you think it's too bright. I do like that it's much, much easier to read now. The way it was before, I kind of had to highlight the quoted sections to be able to read them at all, with that dark grey against dark blue, or whatever it was.
by Garth
Tue Nov 12, 2019 2:40 am
Forum: Newbie Help Center
Topic: Getting Started(Updated:Jun. '10)
Replies: 21
Views: 76566

Re: Getting Started(Updated:Jun. '10)

Hi, very interesting. Really useful post. Thank you, I'm new This is a very typical first post for a spammer, and a near guarantee that you are one! On the forums I moderate, when I see this I do a quick search and find the person has left quite a trail of spam, and I ban them and kick them out imm...
by Garth
Fri Aug 23, 2019 10:25 pm
Forum: General Stuff
Topic: Can SMPSs damage retro consoles?
Replies: 7
Views: 5147

Re: Can SMPSs damage retro consoles?

I have designed switching supplies (SMPSs) into several of our aircraft products where they had to be really quiet to avoid getting switching noise into the radios and into the entertainment electronics. Getting such good performance out of them is beyond the capabilities of mere electronics hobbyis...
by Garth
Mon Aug 12, 2019 12:11 am
Forum: Newbie Help Center
Topic: Excessive operand length?
Replies: 12
Views: 6181

Re: Excessive operand length?

I would think that whatever you're trying to do would be better done with macros.
by Garth
Fri Aug 09, 2019 7:57 pm
Forum: General Stuff
Topic: What do you think of FPGAs?
Replies: 51
Views: 33060

Re: What do you think of FPGAs?

A 65816 has 22k transistors? I thought the 6502 had 3500 transistors. If that's correct then how did it jump so much in transistor count? According to https://en.wikipedia.org/wiki/Transistor_count, WDC's 65c02 (ie, CMOS) has 11,500 transistors, and the 65816 does have 22,000. My guess is that the ...
by Garth
Sat Aug 03, 2019 1:25 pm
Forum: Newbie Help Center
Topic: Do you/does it make sense to imitate function calls?
Replies: 17
Views: 10224

Re: Do you/does it make sense to imitate function calls?

These are discussed in my treatise on 6502 stacks (plural, not just the page-1 hardware stack), particularly section 6 on passing parameters and section 14 on local variables and environments. Edit: It shows how to do what rainwarrior mentions below in section 7 , on inlining data. It's mostly about...