F6 bankswitching in discretes?

[jindroush]

Hi,

 

has anybody done subj.? Or F8?

 

Are the schematics available?

 

I don't count Cuttle Cart, I mean simple PCB with 16k eprom and some stuff around.

[CPUWIZ]

Not neccessary anymore.

 

http://www.atariage.com/store/

[jsoper]

Interesting. Is that a custom chip they're doing the BS with? I wonder if they're going to make a RAM version of the 16k board because about 1/3 of the released F6 roms need it.

If you still want discretes, I'll post the schematic in a month or so (drowning in projects)

[CPUWIZ]

It's an off the shelf PAL (Programmable Logic Array) with custom code, written by Joe Grand.

[jindroush]

Hi,

 

it would be still nice to know how does it work. JEDec anyone?

[CPUWIZ]

Jsoper has a diagram on his site.

 

http://www94.pair.com/jsoper/bankswitch_f8.html

[joesmooth]

For the bankswitch boards I designed (that AtariAge sells), I used a standard Atmel 20V8 PLD (Programmable Logic Device) to implement the bankswitching routines. I figured it was easier and cleaner than using discrete logic and would keep the assembly and layout of the PCB nice and simple.

 

The bankswitching routines are described in detail in http://www.tripoint.org/kevtris/files/sizes.txt by Kevin Horton.

 

Basically, depending on the bankswitch routine (F8, F6, F4), the PLD just looks at the A0-A11 addresses until one of the "hot spots" is detected, and then switches banks (just sets or resets one of the higher order address bits). And, A12 is still used as the EPROM chip enable line (must be inverted).

 

Nice and simple

 

Joe

[+5-11under]

I found a GA035 chip that Kevin describes on a Tomcat cartridge (look for a 20 pin dip which is visible without opening the cartride). I also found a Superchip in a Dig Dug cartridge, I think. Note that a lot of cartridges have the bankswitching and Superchip in the same package as the ROM.

5-11under

[Artlover]

Jsoper has a diagram on his site.

 

http://www94.pair.com/jsoper/bankswitch_f8.html

 

Wow, this is the first time I've seen this document. Odd, with all the searching I did. This just explained why I could never get a home-brewed 8k cart to work.

 

Thanks.

[jsoper]

Wow, this is the first time I've seen this document. Odd, with all the searching I did.

I finishing up the F6 one, it's only on my internal site right now. Within the next week I hope to have it out with another project that will really make people hate my guts