It's white lettering so I would guess the 4400.
Yes. Here's all of them. Strange that the StarMax boards are the same, though they're different models (and different board numbers.. so much information to string together without documentation... I feel like a conspiracy theorist with a strung cork board :lol: )
And it's doubly confusing as there's no chart, at least that I could tell, like there is for the CPU PLL (at least on the StarMax boards)—nothing to indicate what it would opt for. Did any Tanzania clones, that you know of, use MFM floppies? Or is it just a holdover from the CHRP directives?
Also, I guess I didn't quite catch what you were describing with your description of the CPU ID and CPU OPTION sections among your boards. The OPTION block is most definitely where the PLL/clock multiplier is set. Do the resistor arrangements differ from
OPTION to
ID on the same board in your collection? Mine match. I'm guessing that the similarities between your 4000 and 5000 boards are because they're set to the same multiplier? I'm assuming that based on the screen-printed chart on the non-4400 boards:
Like you say, I wonder what CPU ID really does... I'm clutching at straws, since I'm only a few years into starting to understand how a logic board and its components all work together. It's probably not memory timing, since that's controlled by the bus speed (
or at least the relative sections discovered by Andreas Kann), but I wonder if there's anything else that would be effected by the CPU clock speed and/or the clock multiplier... serial? video? PCI? Again, clutching at straws there.
Which, as tenuous as it is, kinda goes back to my theory as to the reason for my black-screen clocking attempts. I wonder if the disparity/difference of CPU OPTION and CPU ID is what's causing that, and if they were made identical... but that's a stretch, seeing as (with working RAM anyway) I can achieve a stable OC (and even stable operation at any clock, save the one below the min of the chip) without a match on the sections... I'm tempted to really just go all out with one of my boards to test it. I ordered some jumper blocks to solder in with my last mouser order, I just don't know which one to choose. I've already modified the 5000 board, but I have a 3000 board that really isn't doing much of anything. I wish my second 4400 board didn't just halt booting after the chime, otherwise I'd just use it. Just see whether or not instability occurs with a large disparity, whether a max multiplier can be stable when they match, etc.