Wow! It's really great to see my ideas behind uxForth being taken up and it being able to generate a real application!

Calculating dest = constant - signed byte? Z80:


ld hl,(S1) ;don't care about h, contains garbage.
ld a,l
rla
sbc a,a ;=> a-a-0 or a-a-1 ie. 0 or 0xff.
ld h,a ;hl now sign extended.
ld de,258
or a ;clears carry.
sbc hl,de ;hl=258-S1
ld (dest),hl ;saved


So, z80 is quite straight forward ...

Nice work! I'm sure you'll be a multi-billionaire any day now.

Thanks! Feel free to convert it to the microcomputer of your choice! Remember, Blastar, it's the secret of success!

How did you generate the listing? Is it just a series of screen caps glued together? (And kinda low on readability ...

Back in 1984, the 12 year old Elon Musk wrote a rudimentary video game for his SpectraVideo SV-328 (a Z80 Microcomputer)

https://www.theverge.com/2015/6/9/8752333/elon-musk-blastar-pc-game

Then about 5 years ago someone turned it into an HTML-5 version of the game which you can play here:

http ...

With the y reg optimisation...about 27% faster.
Well, so long as the function you're calling is not using the Y register. If it is, you now need to save and restore it
with every call

I would tend to favour callee-saved conventions. I once wrote a blog post about that:

http://oneweekwonder ...

Think about something like this: while (*ptr) func(*ptr++);

How might a 65T2 C compiler handle this? It's likely it wouldn't use the Y register.


:Foo ;ptr is at s+3:s+2
Bra Foo1
:Foo2
Lda *s+2;
Jsr Func
Inc s+2
Bne Foo3
Inc s+3
:Foo3
:Foo1
Lda *s+2
Bne Foo2
Rts


This sequence takes ...

(Thanks for reappearing, snial! I'd still recommend a new thread, especially as further different avenues have opened up. But also nice to see KDF-9 and Magic-1 referenced! It seems you have the technical background, so might you write an emulator or HDL model of 65T2? Or indeed a C compiler for it ...

Redesigning the 6502 to make it more suitable for high-level languages is problematic. The most important criteria is to be able to support an indexed stack addressing mode.


I was with you until this point. While you can obviously choose whatever design criteria that you want, it's not ...

Hello Garth,

Snial, I don't know much about C compilers' innards; but I think you'll want to look into the 816's stack-relative addressing modes...

Thanks, I'm aware of the 65C816 and it's very extensive addressing modes, including stack addressing modes and its DP register which can function ...

Hi Everyone,

Thanks for all the replies to the idea of the 65T2. Sorry it's taken me so long to reply in turn. I looked at the thread the morning (UK time) after I'd posted it; didn't seem to see any replies at the time and it's taken me a little while to get back to answering. And there's far more ...

The 65T2.


A while back as a thought exercise I worked on a high-level language friendly 6502 alternative I called the 65T2.

65T2.

The 65T2 has the following objectives:

• An 8-bit 6502 type architecture.
• The equivalent MOS transistor and resource budget as a 6502 (or 65C02).
• Better ...

Let's say you have a list of 52 cards and you want to in-place shuffle cards n to m-1 inclusive. Array index is assumed to be from 0

limit=m-n
for l=0 to limit-1
s=rnd(limit-l)+l+n:rem dest is always at l+n
if s>=52 then s=s-52:rem wrap.
d=l+n
if d>=52 then d=d-52:rem wrap.
c=card[s]
card[s ...

Hi folks,

So, here's the answer, let's start with the worst case:

115200 = 347 clock cycles between received characters less 285 clock cycles worst case = 62 free clock cycles between characters


The only acceptable criteria for the software is whether our code will always work; not work on ...

then the byte parallel algorithm still requires too many cycles.

And yet - you may be quite surprised to discover this, but further analysis will show there should be plenty of time for my byte parallel routine within your interrupt code at 115200 baud.

For the moment, I'll leave it for our avid ...

Using the OP's Byte Parallel routine would be on the edge every 256 days for 115200 baud rate

Gosh-thank you for spending the time to work out whether my routine could be used!

It looks like it's fairly close. It's worth noting, the timings for my routine are based on evaluating a whole packet ...