BigDumbDinosaur wrote:
Yuri wrote:
Okay,
Redrew this in KiCAD.
Have you not read the preceding comments about mixing logic types? You should not use 74-series TTL devices, e.g., 74F, in a CMOS system. In your circuit, given that it will be running at a relatively low Ø2 rate, you should use 74HC devices.
I did. I'm drawing what the circuit currently looks like, not what I will be changing it to. My goal was just to show what the logic around the address decoding is doing.
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You cannot connect RDY directly to VCC. That was also pointed out to you many posts ago. RDY is a bi-directional signal and will be driven low in the event the MPU executes a WAI instruction, whether intentional or not. The way you have it would result in the MPU trying to short out the power supply. Use a 3.3K pullup resistor on RDY.
I must have missed that. I went back and looked, but I don't see that comment. (There a lot of comments about caps and the logic families, but I don't see anything about adding pullups on the the pins?)
Anyhow, the data sheet does specify it's bidirectional, so that's my bad for not paying closer attention to that.
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I recommend you use separate pullup resistors on NMIB, BE and SO. Doing so will allow you to use those inputs in the future without having to cut connections. A convenient way to do so is to use a SIP-style, bused resistor network, which you can also use to pull up RDY.
I have some 10ks that I ordered in a SIP package that should come in soon. I have some individual 3.3Ks, but not in a SIP. The NMIB, BE, and SO pins are pure inputs though. I can definately see the case for something like NMIB or BE so one or more devices could drive the line, but SO is suggested that it shouldn't be used any longer according to the datasheet.
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Also, that hookup to IRQB on the 65C02 is wasteful. One section of a 74HC08 is all that is needed. Or use one section of a 74HC11 and tie the unused input(s) to VCC.
Well I needed a not gate for the enable line of my 74139 that's doing the address decoding. So that one IC is doing that and the logic to handle the interrupts. If I use a 7408 I'd need another IC to put a not gate in there, which was space I didn't really have on that bread board. In the future I might look at replacing the address decoding with a GAL or something. (As soon as I can figure those things out)
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I don’t do GitHub. I can never make head or tails out of it.
Then here's the documentation page of the assembler:
https://wla-dx.readthedocs.io/en/latest/It isn't the greatest thing sense sliced bread, but I had it working and doing assembles of 65816 and 6502 stuff. So that's what I've stuck with for now.