A7800 5.2 release

[RevEng]

a7800 v5.2 has now been released at github.

 

Whats new in this release:

• pokey poly9 sequence correction
• pokey init state corrected to match real hardware

 

A big thanks to @rensoup for pointing out the poly9 bug.

 

Heads up that the update to the pokey init state means that a good chunk of the 7800 pokey demos aren't functioning under the new release. Those demos aren't setting the b0 and b1 bits of SKCTL high, which takes pokey out of reset, and is a required pokey setup on real hardware. Some flash carts may take pokey out of reset during startup, but this doesn't happen on retail and homebrew pokey carts.

 

Once again, @Trebor and I hope you enjoy it!

[Eagle]

Good job @RevEng

 

I'm testing discrepancies between emulators and real hardware (my new hobby  ) 

It would be great if someone could check the NTSC version on real hardware.

BTW I'm surprised again by BupSystem ?

edit: not anymore  I have just found a way to detect BupSystem as well.

 

detect_emu_PAL.a78 detect_emu_NTSC.a78

Edited June 26, 2022 by Eagle

[+mksmith]

Well done gents - thanks again for your efforts ???

 

[Eagle]

Fun fact about Atari 7800 

 

	lda $700	;A=7
	sta ...
	ldy #$01
	lda $6ff,y	;A=6
	sta ...	

 

HOW???????

 

detect_emu.a78

[RevEng]

Floating bus reads usually return the last value on the bus, due to capacitance. The last byte in each of your LDA opcodes is 7 and 6, respectively.

 

But this isn't universal. 1 in 10 (1 in 20?) consoles doesn't have sufficient bus capacitance to keep the value.

[+TwentySixHundred]

Thanks for all the hard work and continuous updates guys. Always appreciate the dedication that goes into these projects which gives us end users a better experience ?

Edited June 28, 2022 by TwentySixHundred

[Ecernosoft]

Nice!