Need testers: “GR8RAM” 8+ MB Slinky/RamFactor RAM card for Apple II series

retr01

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Jun 6, 2022
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Hey @Zane Kaminski, I see there is a 16 MB option. :D @niek, who created the AppleSqueezer GS, could only push it to 14 MB with an update for the GSOS for now. However, he says that it's possible to go more than that.

I was thinking 16 MB, so 8 MB is the ROM Disk while the 8 MB is memory. Could that work? Don't worry about batteries or keeping it powered o whatever. As long as it is 8 MB EEPROM and 8 MB RAM, could it work even from the memory slot in the IIGS? Imagine the IIGS automatically booting into GSOS and loading all that cool stuff fast as possible. :)
 
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Zane Kaminski

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Sep 5, 2021
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There's not too much more testing to do on this card but I will of course have future Apple II products which need testing.

I have a prototype design for a 6502 core which should eventually make its way into an accelerator card. I call the core Sweet65, in reference to the Apple II's Sweet16 16-bit "virtual machine" thingy. Altogether it's under 5000 lines of code. Once the chip shortage is over I can put it in an FPGA (I'm eyeing Lattice MachXO2-4000) and it'll make a nice accelerator for the Apple II. So there will be opportunities to test that since a CPU requires a lot of verification and testing to make sure it's 100% accurate. I'll make the Sweet65 repository public sometime but I haven't touched it in a few months and I'd like to get some products (including GR8RAM and WarpSE) released before revisiting it. So that's in the future.
 
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Zane Kaminski

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Hey @Zane Kaminski, I see there is a 16 MB option. :D Niek, who created the AppleSqueezer GS, could only push it to 14 MB with an update for the GSOS for now. However, he says that it's possible to go more than that.

I was thinking 16 MB, so 8 MB is the ROM Disk while the 8 MB is memory. Could that work? Don't worry about batteries or keeping it powered o whatever. As long as it is 8 MB EEPROM and 8 MB RAM, could it work even from the memory slot in the IIGS? Imagine the IIGS automatically booting into GSOS and loading all that cool stuff fast as possible. :)
Oh, regarding 16 MB, it's fairly different between the IIgs and this card, which is basically an AE RAMFactor clone. IIgs can't use all 16 MB because it has I/O in bank E0/E1 and ROM in banks F0-FF. So you can only use banks 00-DF for RAM, totaling 14 MB. You could sprinkle RAM in the unused banks E2-EF but it would only be 896 kB more RAM and it wouldn't be contiguous so that's not so useful. In a RAMFactor-type RAM, the issue is different. There is a 24-bit address register in the card so there's no memory map related issue going out to 16 MB (i.e. using all 24 bits). The problem is that many cards ignored the high bit and only looked at the 23 lower bits. Therefore any address starting with 0 referred to the same location as an address starting with 1. Since the high bit of the address doesn't matter, some programmers used it to store an extra flag. Thus the incompatibility--if we make that high bit count, then the flag stored there by a program would "matter" and the program would be "accidentally" referring to one of two spots depending on the flag value.
 
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