16MB might work out good for other usage actually. With flashy clock I intended to copy ROM into SRAM because the ROM speed maxes out at 55ns. I really need something in the order of 10ns ROM. But the only thing that fast was SRAM at 10ns speeds. I hit a bit of a brick wall because my PLD simply ran out of space to fit all the logic inBadwolf wrote: ↑Fri Jan 14, 2022 8:25 pmI'm hoping to get SDRAM working and send one to Exxos to have a play with. He may be able to drop in his accelerator equations, for example.
This initial version won't be so cheap. The SDRAM was out of stock so I'll be putting a 16MB one on there and the CPLD I'm using is intentionally the biggest that'll fit the footprint to aid development.
As you undoubtedly know, normally this is what the 030 MMU does/can do, to remap ROM into RAM. But this is not so simple with a 68000. So what was on the cards was flashy clock would copy ROM into RAM at power up. Basically it would need a huge binary counter to step through the addresses. Later I thought of just cheating and copying the ROM with the CPU after power up. Because then a register can be flipped to SRAM when the copy has been done. So any ROM addresses will actually be read from a dedicated SRAM.
While there are programs which allegedly can copy ROM into alt-ram anyway, I have never got these to function properly and just see it as a total PITA thing to do anyway. I also think TOS is not happy running from alt-ram, which I ran into with the TF536.
So just copying the ROM to a new fast small SRAM was the plan. Then there is no software intervention or anything else required. As far as the system is concerned ROM is still in ROM space, just running from SRAM at much higher speeds. TOS Will still running the expected address ranges. Everything should be overall happier!
8MB not technically the limit anyway. I think you could go up to 10MB or even 12MB.. But people moaned about that because of graphics cards and other stuff in the address range. But if this was switchable anyway..
Indeed this is why I cannot really open source or collaborate with anyone else on my projects. Imagine if I gave away tomorrow everything I have ever worked on, I might as well close shop because every man and his dog would be making it. It is also again the problem of open sourcing stuff as terrible fire and others have found out. Good in some respects but not in others. UBE made and sold his VGA adapters, He was selling them to me and I was selling them in my store, so he was getting something as well as myself. But he also open sourced it, then loads of other people basically cloned it. In a way UBE shot himself in the foot because you cannot really give something away and sell it the same time. Undoubtedly when you open source something everyone will rip it off with or without your permission anyway.Badwolf wrote: ↑Fri Jan 14, 2022 8:25 pmAye. Although, Darklord, co-operation in general is a bit awkward as basically I'm a hobbiest giving away the designs and not making them. I can't really sidle up to Christian or Matthias and say, "Hey, boys. Let's get these two talking" until I actually have a working design. Even then, mine's likely to be evolved and changed by people -- it's not really a product. If those guys are selling and supporting theirs, they don't want that unknown interfering with things.