It's not clear to me what the difference is between INT and CINT, but it may be subtle.

It's described in the manual: CINT returns an integer, INT returns an integer-valued single precision floating point number. Both are floor operations, so they'll both choose the same integer if it's in the ...

I don't see a 16V8 being suitable at all - it has only 8 flip-flops, all of which are directly connected to pins. The '670 has 16 bits of state, with four multiplexed onto each output. A CPLD like the ATF1502 should be able to do it if you wanted to go that route.

Or alternatively, use the 74HC670 ...

(As noted upthread, it feels to me like an attractive approach would be a multi-design which can somehow be configured as one of a number of 40-pin chips. You'd need at least one spare pin to manage the configuration, if you want it static.)

That sort-of exists in the form of Tiny Tapeout https ...

It makes me wonder how those single chip scientific calculators of that era were made.

Ken Shirriff of course has a good write-up of the Sinclair scientific calculator https://static.righto.com/calculator/sinclair_scientific_simulator.html . There's a commented disassembly of the code (in a ...

It's also connected to a test point. It's possible that it's always high under normal operation, but can be pulled low during testing to put the system into a known state. That would require the circuit it's attached to (which looks like video generation) not minding that various flip-flops are in ...

I use { } to introduce new scopes, as you suggest. It works very well.

What assembler are you using for that?


My own. Doesn't everyone write their own assembler? :-)

It does support a 65C02 target, but I use it mostly for the 65020. A consequence of designing your own processor is that no one ...

I use { } to introduce new scopes, as you suggest. It works very well. I can have meaningful labels that don't have to change as code is added, and those labels don't need ugly (to me) annotations to say that they're local. Most labels are local, and I don't like having to do extra for the common ...

I believe Mouser shipped me a 0.0360 Mhz crystal

That sounds very unlikely to me. Vishay make crystals at exactly 32.768KHz, and they make them at a range of frequencies from 3.579545MHz upwards. They do not, as far as I can tell, offer a 36KHz crystal. That's the sort of frequency you'd have to ...

Does the PIC have an option to change the drive speed (rise/fall times) of the output like STM parts do?

Quickly looking at the datasheet, I think the SLRCON* "Slew Rate Control" registers might do that. They default to 1, which means slow. And reading further (in the I/O and CLKOUT Timing ...

It would be a lot easier to help if you could post the code you're looking at.

I found a binary of the Atari 400 BASIC cartridge at https://www.atarimania.com/utility-atari-400-800-xl-xe-basic_13284.html and disassembled that (attached). It's in CART format, which I know nothing about - I just ...

If the PRNG is any good, messing with it in an attempt to introduce "more randomness" (without theory or testing) is only going to make it worse. Almost certainly much worse. If you want non-determinism, use it when you're selecting the seed and then leave it alone.

In this case, there is a cycle ...

ADC and SBC both add the carry flag to the sum. So ADC #0 will either leave A as it is, or add 1 to it, and SBC #0 will either subtract 1 or leave A unchanged. Without seeing the code you're looking at, my guess would be that these instructions follow other ADC or SBC instructions, and are used to ...

So with both the doubly linked list and a singly linked list (both of which are basically just a FIFO (queue) instead of a FILO (stack)) you still effectively have a gap problem.

Press A, Press B, Press C, release B....

You now have a gap in the middle of the list

Not with the system I was ...

If I'm understanding the problem correctly, the way I'd do it would be to maintain a doubly-linked list of currently held keys. When a key is pressed, it is inserted at the head of the list. When released, it is removed from the list. That's two arrays of 76 bytes: one holding the "next" pointer for ...

It is correct—I’ve used the algorithm in several places.

I don't think it's right either. Have a closer look - it does not do what you're claiming. If o_di_end is not a multiple of 16, it's adding o_di_end/16. That's only going to give you a multiple of 16 for a few values, by coincidence ...