As far as proof of 6502's performance relative to other CPUs with a normalized clock , all you need to do is count the cycles in your particular application. Yes, yes, the 68000 can pull off 2 MIPS performance at 8MHz, but know what? A 65816 at 8MHz will pull off 4 MIPS on average. At this point ...

Yes, I forgot about the times they imply a high "1" bit that is not expressed. To do an addition though, the smaller number has to be right-shifted, ie, non-normalized, to line up bits properly for the addition; and to line them up, the smaller number has to be shifted all the way to the bit bucket ...

BTW, a similar thing can happen with floating-point too, depending on the precision used. Exponent adjustment prevents overflow; but for a given number of bits of mantissa, if you add enough input numbers together, you will reach intermediate results high enough that many of the following input ...

If anyone can find a binary representation for 0.3 or 0.1, let me know. While you're at it, publish a paper in ACM or IEEE Computer, and earn yourself a position at some prestigious university. Even with *80* bits of precision, you can't represent either number precisely, and so when printing ...

Hi all,
for some fun, I am attempting to make a 'compiler' that compiles a high-level language similar to Pascal (Delphi) into C64 assembly code, and I have some number questions if I may :)
C64 assembly code? Is that anything like 6502 assembly language? <Grin>

hahaha! Good one :)

I need ...

The pages came up for me, but it took a looooooooong time.

I'm not sure if the book of Impossible Routines would be very useful or entirely useless.
I couldn't find that one. Where is it?
A little more than halfway down the page.
http://www.bombjack.org/commodore/books/pdf/Impossible_Routines ...

I think you may be referring to the config of the 6850? We've performed a Master Reset, but have we left it in a 7bit mode? Yeah, I meant the config of the 6850. I didn't see anything about what a Master reset actually did, does it set a 8 bit data word size? if it doesn't, is Master reset needed ...

I was looking at the docs (because I wondered if it was possible to do LSR status) and noticed that it appears that the code selects 7bit word length, if I read it right. It would be a bit dificult to write a second stage bootloader that couldn't even use load or store opcodes :)



edit: if we dont ...

Couldn't you also get rid of the INX if you used 0 as an EOF byte?

Who said anything at all about shorting the pin high? I certainly never said that.

Sorry, didn't mean to imply that you suggested shortening the pin high, I was still thinking in the context of what I wrote earlier. If you just pull it low with existing HW you don't need an extra or gate to ...

"oVerflow Flag (P.V)"
-Third use: Sticky input bit. Connected to the SO pin.


As an input or output?
Ie. does the pin effect the register or vice versa?
Input, the pin effect the register. I think it's edge sensitive, but don't remember which edge.


"How can I disable Non-Maskable Interrupts ...

"How can I disable Non-Maskable Interrupts?"
-By not acknowledging a NMI you'll effectively mask further NMIs

This is actually false; the CPU will happily attempt to handle another NMI if the interrupt pin is strobed. "Acknowledging" the NMI is implicit within the CPU.

External logic is ...

if you/others can/will highlight to me any mistakes on my page, they WILL be corrected!

Not exactly mistakes, just thought I'd mention....



"oVerflow Flag (P.V)"
-Third use: Sticky input bit. Connected to the SO pin.


"What is an Interrupt?"
-Strictly speaking, it's the voltage itself that ...

I don't know what bug the code is supposed to show. That executing illegal opcodes leads to various undefined results is no surprise, that's why they're called illegal opcodes.

All the illegal opcodes have been documented in various texts, like this one: http://www.ffd2.com/fridge/docs/6502-NMOS ...

I remember running a c64 program that would test all opcodes for correct behavior, but I don't remember what it was called or anything. Searching for 'c64 emulator test suite' returns some results, like http://www.zimmers.net/anonftp/pub/cbm/crossplatform/emulators/pc64/ (near bottom). I don't know ...