6502.org

Here's an idea, inspired as a mutation of an idea of Dr Jefyll's: what old threads would you like to share, here on 6502.org?

Only two rules:
- Can't have a thread you created yourself
- Can't have a thread started this year, or a sticky thread

Also, please present your finds as linkified thread titles like so:

• Timing Diagrams. Visualizing 65xx Timing. (2014, Dr Jefyll)
  Detailed 6502 block diagram (2006, BitWise)
  Extra cycle in crossing page boundary question (2015, Bryan Parkoff)
  A program for today (2011, dclxvi)

If you comment here, you have to include at least one fine old thread link!

Here's another one:

• 6502-Core Comparisons: Fitting a Xilinx Spartan 2 XC2S200 (2010, ElEctric_EyE)

(Things were quite lively for a while in the world of 6502 cores and FPGAs, but seem to have gone a bit quiet.)

Any more fine threads from anyone?

Here's a few I enjoyed:

• Visualizing the 6502 (2010, BigEd)
  A taken branch delays interrupt handling by one instruction (2010, HiassofT)
  NMOS 6502 Reset bug (2011, Dr Jefyll)
  binary to ascii (2013, wwl)

Nice choices Rich - thanks!

Here's my obligatory additional submission:

• Working SBC-3 (2008, 8BIT)

There are much more but to throw them in:

• BRK detection (2002, schidester)
  String Comparison for PASCAL style Strings (2005, Wheels)
  Fast CRC without tables (2004, debounce)

Nice finds, GaBuZoMeu, thanks for stepping up to the challenge!

Obligatory threads... here's a couple recently mentioned by Garth and Jeff, respectively:

• Survey: A 65C02-based PC (2003, 8BIT)
  TTL 6502 Here I come (2015, Drass)

I always get a laugh when someone declares a particular 6502 feature to be useless, as I've found a number of uses for BRK, as well as its close cousin in the 65C816: COP.

Apparently, Mr. Schidester has not engaged in the debugging of a program that was executed with the G ("go") command of a typical 65xx machine language monitor. If he had, he would have found BRK to be a convenient means of temporarily halting program execution to examine the registers, dump memory, etc. In fact, I have a macro called (what else) BREAK that I use to put break points into programs in areas where I suspect I might run into bugs.

Declaring a 6502 feature useless reminds me of the periodic debates on the value of the 6502's decimal mode (I use it for binary-decimal conversion) or (<zp>,X) addressing (my 28L92 driver makes extensive use of that addressing mode to select which channel is being processed).

Thanks for taking part BDD - but where's your mini-challenge entry? You seem to have mistakenly taken exception to some small part of an interesting old thread here.

Oops, almost forgot the obligatory fine thread from the archives:

• the fast realization of π-spigot algorithm (2016, litwr)

How about some back-and-forth about assembler syntax (Mats, Jan 2004)?

Thanks BDD!

Obligatory:

• Mini version of the OSI-300 trainer (2015, ChuckT)

Any more responses to the mini-challenge? Here are two more threads for your retroreading pleasure:

• 65816 direct threaded NEXT (2005, dclxvi)
  4MB SRAM Module (2011, 8BIT)

This one is exceptional I think:

1. Getting young people into 6502

Good find GaBuZoMeu! I enjoyed reading that 2013 thread.

Obligatory thread... let's see... how about

• Did commodore attempt development of an upscale 6502 (2013, carmel_andrews)
  Static recompilation of 6502 machine code from NES ROMs (2013, fachat)

UM* (multiplication) bug in common 6502 Forths. Includes good animation of several multiplication algorithms by Dr Jefyll.

A fine one that presumably never will finish:

• viewtopic.php?f=8&t=1603 (BigEd, 2010)