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Are either of these 'new' Saturn 128k designs open source, or have they been made available to the Apple II community?
I'm looking to have a play with a variation of this to use in the Apple III, and it would save some time reinventing the wheel again.
/Rob
Have you tried one in a III? I know that many cards wont work because shared rom space isnt supported but the saturn card doesnt use shared rom.It just asserts the inhibit line and maps over the rom address space.
No, i have not tried one. I do have a clone of the original saturn card and its too long to fit in the A3. You made me think that if i have the mother board out and i use a bus extender card it will fit. I'll give it a go.
The Titan ///+II cards made for the A3 are basically a saturn 128k plus some extra logic to always decode in slot 0, a game port, and a way to enable disable the card.
/Rob
The extra features would need a 2nd GAL , some passive components and a 556 timer chip. It would be doable without too much trouble.The biggest impediment is I dont have an Apple III to test in and international mail is near comatose.
I never found the 1.1 JEDEC file for the GAL in this thread? Was it available somewhere?
He's accessible, usually, on FB messenger, so best thing to do is ask him.
WRT building this yourself - I've built two from David's bare boards. It is VERY parts finicky. David was helpful. I even mailed a completed one back to him for him to diagnose the issues I was experiencing.
I had zero luck using modern Atmel GALs. I spent $50 on GALs and none of them worked. Result: I have a stash of perfectly good Atmel GALs in a drawer waiting for a project of some sort.
I also had zero luck using modern SRAM from Digikey. It would flake out on higher addresses about 80% of the time. I ended up buying "questionable" chinese sourced SRAM from AliExpress and it worked reliably.
Only the combination of Lattice GAL, used Samsung branded SRAM (from Aliexpress) and high speet 74HCT logic chips worked for me.
So while I do have two working cards now, it was a slog and in the end was way more expensive and took months longer than it should have.
I have Lattice GAL, but it's 25ns, which may be too slow?
Also, I have 74LS74... and I didn't socket them. Luckily I have a desoldering tool so that won't be too bad if the vias survive.
I was hoping the timing fix in 1.1 would negate me having to do that...
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