What does the microcode 'FF' symbol represent? #27
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I've been looking over the schematic and microcode listings. But, I'm having trouble figuring out what the 'FF' microcode signal represents and where it is implemented. For example:
I'm guessing FF is a constant value generation and might be a bitwise combination of multiple signals, but I can't really trace it back. As far as I can tell, there aren't any microcode signal definitions in this repository. Any insights would be appreciated! |
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Replies: 2 comments
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Hi, as you can see from the schematic, the bus is pulled to 5V (HIGH) by 8x 330 Ohm resistors. So if all output control signals are off, the bus will represent the value 0xff. FF is just a dummy "control signal" to visualize steps where this value is sampled by inputs. Please note that the "Minimal 64" is a legacy design. I recommend checking out my "Minimal 64x4". |
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Ah, gotcha. Thank you. Yeah, I can see in the Minimal 64x4 there's an active device driving constant value now. That makes sense. I've been looking into the data paths of your processors and that was just a hangup for me :) |
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Hi, as you can see from the schematic, the bus is pulled to 5V (HIGH) by 8x 330 Ohm resistors. So if all output control signals are off, the bus will represent the value 0xff. FF is just a dummy "control signal" to visualize steps where this value is sampled by inputs.
Please note that the "Minimal 64" is a legacy design. I recommend checking out my "Minimal 64x4".