The 7800 Minnie In-Cart Sound Chip

[bikeguychicago]

In retrospect, it was a mistake to not include enhanced sound (Pokey or otherwise) in the console itself. It pretty much hobbled the machine to be developed to the lowest-common denominator.

[Lynxpro]

4 hours ago, bikeguychicago said:

In retrospect, it was a mistake to not include enhanced sound (Pokey or otherwise) in the console itself. It pretty much hobbled the machine to be developed to the lowest-common denominator.

 

If we take GCC at their word, they claimed they couldn't cram anything else on the 3600/7800 motherboard based upon the requirements Warner gave them in basically re-using the 2800/Sears Video Arcade II case. Maybe they could've gotten around that had Atari Inc provided them with the Jane/Janus/whatever that rolled up the 6507/TIA/RIOT all in a single chip solution. But even flash forwarding into Atari Corp's days, there are very few of those chips used in the 2600jrs out there. Apparently, Atari Corp inherited enough inventory of all of those individual chips that it negated any cost savings of manufacturing a single chip at that point. Although the 7800 does not have a separate 6507, that would've potentially saved space with the combination of the TIA and RIOT. Which would've freed up space for the POKEY to begin with. GCC probably would've still sold Warner on the MINNIE/GUMBY option though as making the system's audio even that much better on a cart-by-cart basis. Oh well.

[+Defender_2600]

1 hour ago, Cyprian said:

I wonder how they calculated the frequency:

 

28000Hz * (freq. const. / 65536) = output frequency

and for frequency constant = 0001H they get 2,34Hz  oscillator frequency

 

My calculation gives different result: 28 000,00  * ( 1 /   65535) =  0,427252613

 

 

 

 

http://7800.8bitdev.org/index.php/The_7800_Minnie_sound_chip

 

 

[RevEng]

2 hours ago, Cyprian said:

My calculation gives different result: 28 000,00  * ( 1 /   65535) =  0,427252613

Take the reciprocal of that answer. It looks like they gave the formula for the period, rather than the frequency.

It's forgivable, given it's early internal documentation, and not a math textbook.

 

[Cyprian]

misery solved

thanks @RevEng