The MOS 6502 and the Best Layout Guy in the World • Hacker News Board

Re: The MOS 6502 and the Best Layout Guy in the World

#51

Post by exception » Tue, Jan 04, 2011, 10:21 PM UTC

Flow wrote: post #43

rbanffy wrote: post #42

Earlier quoted context omitted.

I will have to dig up my 6502 documentation, but, IIRC, by the time the processor executed the NOP (CLI, INX etc) it already fetched the next instruction, so, if it's another NOP, it will complete in one cycle instead of two. Unless you crossed a page boundary, which implies a one-cycle penalty.

I see, but that's not how it worked on the C64 at least. I did some raster-programming and counted cycles a lot.

Yes you are right, the instruction timings were very exact as far as I remember. The only cases where there was an option was in the case of a branch taken or not.

Re: The MOS 6502 and the Best Layout Guy in the World

#52

Post by wladimir » Wed, Jan 05, 2011, 2:20 PM UTC

rbanffy wrote: post #39

forinti wrote: post #27

Earlier quoted context omitted.

The 6502 was faster at accessing memory. I remeber Elite running a lot better on a 2MHz BBC Micro than on any 3.58MHz Z80 based micro, like the MSXs.

The MSX 1 also had a hideous design flaw (for a gaming machine) that hid the framebuffer from the processor. IIRC, you had to do a couple IOs to get a single byte to or from the VRAM.

I remember the MSX2 had exactly the same flaw, it had a bigger video memory and some 2D acceleration primitives, but the access method was the same, through vpoke/vpeek.

Re: The MOS 6502 and the Best Layout Guy in the World

#53

Post by wglb » Sun, Jan 09, 2011, 3:51 AM UTC

amichail wrote: post #5

rbanffy wrote: post #3

Earlier quoted context omitted.

That's the sensation of working with someone who's incredibly good. And, BTW, the 6502 was a work of art. Simple, elegant and fast (even at 1 MHz), it ran rings around the Z-80's you found in more expensive computers of the time. Plus, it was delightful to program.

Plus, it was delightful to program. Simple maybe, but not delightful to program. I don't know of any assembly language that is delightful to program. BTW, I knew someone from junior high & high school who could write code for the 6502 using a hex dump with amazing speed. You might have heard of him: Randy Linden.

Perhaps your experience is limited.

The PDP 10 had a delightful instruction set. While I didn't use the 7094 instruction set, many seemed to feel that it was a good set, and felt let down by the 360 instruction set when it came out.

The motorolla 6809 was nice, and it seemed to have a flavor of the pdp-11 (which itself was a delightfully simple and elegant set).