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scotty

6510 in A8-bit?

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Would it work? 6510 is compatible with the 6502, only difference being bank-switching. Do not see why it wouldn't. Years ago, I put a Motorola 68010 in a 1040 ST, and while it DID work, there were some (not a lot but some) programs that did not work. Thoughts?

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I don't think it'll work without an additional circuit due to the fact that Atari's 6502 "SALLY" has a 'halt' pin/function that the standard 6502. The 6510 does not appear to have this HALT Pin either.

 

The exception might be the 'early production Atari 400/800' machines which actually used a regular 6502C and had the circuitry on the board instead of the CPU.

 

https://www.atarimax.com/jindroush.atari.org/achsally.html

 

Description
6502 is the heart of the computer. It's based on MOS Technologies 6502. While the 400/800 models contain a generic 6502 CPU, all of the XL/XE models contain Atari's customized 6502C chip. 6502c has an extra line called HALT. It is controlled by ANTIC which it uses whenever it needs the /jindroush.atari.org/data/address bus. The HALT line must be pulled high for the chip to work. Early 400/800 NTSC computers used a standard 6502 and 4 additional chips to stop the processor when ANTIC needed the busses.

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An OS rework would be needed so locations 0/1 don't get stomped on. These are just work areas mainly used in cold/warmstart. I think there is one XL OS (the one the spontaneously resets when you change a cart rather than doing a lockup like later ones) that can have issues if you change contents of one of those locations.

 

Likely the old way of halting the CPU with external circuitry would be needed like early 400/800.

 

The 6510 has the BA pin that I think can be used like /Halt but I think it only works once the current instruciton has finished (or similar).

Generally the C64 uses /RDY when doing DMA bursts and it needs a few cycles pre-emption since write instructions can delay it's effect.

 

Possibly the biggest problem - can the 6510 operate at the higher speed? I suppose if not then the CPU from a C128 could be used as it has the "Fast" mode where it operates at 2 MHz.

 

But overall - why? Without extensive further rework to use the 6 IO port bits as either bankswitching or something else (yep, the C64 only has 6 bits of IO, not 8 on the CPU), the CPU is functionally the same from a programming POV.

 

I guess one project might be to do an XL with 4 joystick ports that work with all games including those that read the ports directly. But then you'd get the OS issues and software aplenty that stomps locations 0/1.

Edited by Rybags

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SID way more desirable though apparently getting rare thanks to people harvesting them for stereo C64 or blackbox type projects.

 

Didn't candle even make an interface with proper asynchronous bus interface so it could be run at it's proper speed?

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Yeah I remember some stuff but wonder why SID cards did not appear more often as project.

 

Or some kind of YM-chipset as sound card. We have video enhancements, cpu, ram, flash/hdd but except stereo not much more?

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YM as per ST/Spec/BBC - IMO an inferior chip by a good margin. The only advantage is that it has better frequency range and resolution in the default mode vs only 2 channels for Atari if we want to match it.

But far outweighed by Pokey's effects and exploits.

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Looks like they've developed a drop-in SID replacement to solve having to steal chips from other machines, and add more features (stereo too) https://www.c64-wiki.com/wiki/SwinSID

8-bit Guy reviewed that on his YouTube channel this past week. It appears relatively compatible with both versions of SID but it’s not perfect.

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Why isn’t someone doing this with POKEY? The 7800 community needs it badly for homebrews!

 

This year, in the Abbuc HW contest (main thread at: http://atariage.com/forums/topic/277608-abbuc-hardwarecontest-2018/)

 

 

PokeyMAX

 

Introduction

The PokeyMAX is a complete replacement for the Pokey chip.

Features

 If pokey is socketed, zero wire installation (mono)

 Dual pokey fashion

 pins for 3 audio outputs (left channel / right channel / mixed)

 Small footprint, only a few mm larger than the original IC

 support all features: 8x paddle inputs, IRQ, serial I / O, audio output, two tone mode, high pass filter and keyboard scan

 High level of compatibility

 

 

http://www.abbuc.de/community/forum/viewtopic.php?f=15&t=9560

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