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Search took 0.06 seconds. Search: Posts Made By: mc6809e
Forum: Coders. Asm / Hardware 11 April 2024, 04:23
Replies: 91
Views: 5,515
Posted By mc6809e
Reviewing the MC68030 UM reveals the ugly truth. ...

Reviewing the MC68030 UM reveals the ugly truth.

Seems the best that can be expected in terms of hiding by parallel execution any write wait states from a previous instruction appears to be the...
Forum: Coders. Asm / Hardware 09 April 2024, 20:28
Replies: 9
Views: 798
Posted By mc6809e
Keep this in mind: in four plane mode there is a...

Keep this in mind: in four plane mode there is a BP DMA cycle every other cycle. The copper will use the cycles in between. The trouble is that it takes two DMA slots for one copper move. BP DMA is...
Forum: Coders. Asm / Hardware 08 April 2024, 20:46
Replies: 91
Views: 5,515
Posted By mc6809e
Have you tried reordering instructions to...

Have you tried reordering instructions to optimize bus usage?

Mulu.l might be a win if you can initiate a cache line fill or chip ram write just before the mulu.l.

It would require a certain...
Forum: Coders. Asm / Hardware 02 April 2024, 00:43
Replies: 5
Views: 599
Posted By mc6809e
The main thing is to understand is the division...

The main thing is to understand is the division of responsibility between Agnus and Paula. Paula's logic will tell Agnus that it needs a new sample from the stored waveform or that it has reached the...
Forum: Coders. Asm / Hardware 25 March 2024, 18:53
Replies: 14
Views: 907
Posted By mc6809e
You make good points. One thing, though. As...

You make good points.

One thing, though. As long as movem.l uses some addressing mode other than predecrement mode memory is written to in-oder. This works for updating a sprite completely since a...
Forum: Coders. Asm / Hardware 25 March 2024, 15:41
Replies: 14
Views: 907
Posted By mc6809e
The recent thread by !ZAJC!...

The recent thread by !ZAJC! https://eab.abime.net/showthread.php?t=117203 suggests that in theory MOVEM.L to sprite registers with race-the-beam style/cycle exact programming is possible and would...
Forum: Coders. Asm / Hardware 25 March 2024, 02:39
Replies: 13
Views: 897
Posted By mc6809e
Hope you get it working! Noticed you use...

Hope you get it working!

Noticed you use octamed. You trying to generate noise for percussive sounds?
Forum: Coders. Asm / Hardware 24 March 2024, 23:35
Replies: 14
Views: 907
Posted By mc6809e
Data can be changed, too. In fact a write to...

Data can be changed, too. In fact a write to sprxdata is necessary to rearm the sprite if the sprite was disarmed at some point with a write to sprxctl.
Forum: Coders. Asm / Hardware 24 March 2024, 17:01
Replies: 13
Views: 897
Posted By mc6809e
Crazy idea: Set up line mode to draw a vertical...

Crazy idea:
Set up line mode to draw a vertical line from top to bottom.

Put random in BLTADAT. Put random in BLTBDAT. Set minterms for D= A xor B xor C.

Use CPU to change BLTADAT and BLTBDAT...
Forum: Coders. Asm / Hardware 21 March 2024, 01:59
Replies: 13
Views: 1,034
Posted By mc6809e
Great work! Love it. I wonder, how badly are...

Great work! Love it.

I wonder, how badly are MULs and DIVs affected?

I have this fantasy that one day someone will write 3d code that includes a math scheduler that tries to time the use of...
Forum: Coders. Asm / Hardware 19 March 2024, 02:10
Replies: 13
Views: 1,034
Posted By mc6809e
The table here might be of interest to you:...

The table here might be of interest to you: https://gist.githubusercontent.com/cbmeeks/e759c7061d61ec4ac354a7df44a4a8f1/raw/c8f250348f24fdf53a1b5e71b7734ecefef9b3d2/Yacht.txt

Every 'n' or 'p' or...
Forum: Coders. Asm / Hardware 17 March 2024, 03:49
Replies: 26
Views: 1,453
Posted By mc6809e
Oh, c'mon. You know you want to. :) I have...

Oh, c'mon. You know you want to. :)

I have been wondering what a flat creen might do if the VHPOS is walked back 16 pixels a few times per line. HSYNC frequency would be reduced but a few...
Forum: Coders. Asm / Hardware 15 March 2024, 19:34
Replies: 12
Views: 661
Posted By mc6809e
If it were me and 16 colors were enough I'd just...

If it were me and 16 colors were enough I'd just use attached sprites but he asked about 16px wide bp and who am I to judge?
Forum: Coders. Asm / Hardware 12 March 2024, 23:04
Replies: 12
Views: 661
Posted By mc6809e
What if the copper is used to turn bp dma on and...

What if the copper is used to turn bp dma on and off using DMACON? Does a match with DDFSTRT turn it back on if the copper turns it off? Is bp dma restarted by the copper if it's already off because...
Forum: Coders. Asm / Hardware 01 March 2024, 16:56
Replies: 7
Views: 614
Posted By mc6809e
I'd be interested in seeing how DMA affects...

I'd be interested in seeing how DMA affects various techniques. With lots of DMA the goal might be to minimize the ratio of instruction fetch to actual memory read/writes instead of raw speed,...
Forum: Coders. Asm / Hardware 29 February 2024, 18:44
Replies: 79
Views: 13,466
Posted By mc6809e
With the bonus that those accesses to that 256k...

With the bonus that those accesses to that 256k sram are contention-free.

Wish they'd kept at least some tiny bit of sram on the 500/2000. Even 256 bytes would have been useful.
Forum: Coders. Asm / Hardware 29 February 2024, 00:19
Replies: 6
Views: 503
Posted By mc6809e
Link is borked.

Link is borked.
Forum: Coders. Asm / Hardware 22 February 2024, 08:49
Replies: 21
Views: 1,248
Posted By mc6809e
Movep.l ends up being a bit slower. 48 cycles for...

Movep.l ends up being a bit slower. 48 cycles for each pair of movep.l instructions. Same as four move.b (ao)+,(a1)+ instructions except using movep.l code still needs more time to get shifted bytes...
Forum: Coders. Asm / Hardware 21 February 2024, 18:13
Replies: 338
Views: 387,845
Posted By mc6809e
Well I wouldn't necessarily expect completely...

Well I wouldn't necessarily expect completely arbitrary positions to be workable. I was thinking in terms of a third repeating background.-- 15 color attached sprites side by side behind a PF. No...
Forum: Coders. Asm / Hardware 21 February 2024, 00:56
Replies: 338
Views: 387,845
Posted By mc6809e
So if a bunch of sprites are displayed on the...

So if a bunch of sprites are displayed on the left side of the screen, writing to VHPOSW can get denise to redisplay them again provided a low enough HPOS is written? And Agnus continues to fetch BP...
Forum: Coders. Asm / Hardware 16 February 2024, 18:15
Replies: 79
Views: 13,466
Posted By mc6809e
Amazing! How many cycles left for each...

Amazing!

How many cycles left for each frame? So impressive.
Forum: Coders. Asm / Hardware 26 April 2022, 14:50
Replies: 83
Views: 13,610
Posted By mc6809e
Page mode certainly did exist at the time. The...

Page mode certainly did exist at the time. The Acorn Electron (1983) used it to cleverly reduce the number of dram chips from eight to four. It actually had a four bit bus. Page mode was exploited to...
Forum: Coders. Asm / Hardware 23 April 2022, 03:11
Replies: 83
Views: 13,610
Posted By mc6809e
I think in the end the problem for Amiga graphcs...

I think in the end the problem for Amiga graphcs was lack of appreciation for using page mode for DRAM accesses.

Sure, fmode came later, but it was still limited.

The key to maximizing...
Forum: Coders. Asm / Hardware 19 April 2022, 13:13
Replies: 19
Views: 2,992
Posted By mc6809e
Since you're on the A1200 with a 68020, have you...

Since you're on the A1200 with a 68020, have you tried using movec to temporarily disable the cache? Maybe some of the inconsistency is due to cache effects.
Forum: Coders. Asm / Hardware 16 April 2022, 03:00
Replies: 19
Views: 2,992
Posted By mc6809e
Nah. Your solution is better than you realyze. ...

Nah. Your solution is better than you realyze.

After the first interrupt turn off copper and blitter DMA, "pausing" them both. Then do the STOP.. After second interrupt change background color...
Forum: Coders. Asm / Hardware 15 April 2022, 00:03
Replies: 19
Views: 2,992
Posted By mc6809e
Unless the copper is busy with the blitter.

Unless the copper is busy with the blitter.
Forum: Coders. Asm / Hardware 14 April 2022, 07:46
Replies: 19
Views: 2,992
Posted By mc6809e
I would do a loop until you get close to your...

I would do a loop until you get close to your position, then do a jmp (0, d0, a0) into a block of nops where a0 contains the address of the start of the nop list and d0 has hpos left shifted by one...
Forum: Coders. Asm / Hardware 12 April 2022, 04:04
Replies: 31
Views: 3,650
Posted By mc6809e
Pointless microoptimization: move.l...

Pointless microoptimization:

move.l #$02000000, INTREQ
Forum: Coders. Asm / Hardware 05 April 2022, 23:18
Replies: 41
Views: 5,399
Posted By mc6809e
I like his idea. Seems to be the most efficient...

I like his idea. Seems to be the most efficient way. No wasted cycles or cache space. Does exactly what it needs to do.


Is there ever a problem reading dff000?
Forum: Coders. Asm / Hardware 02 April 2022, 02:07
Replies: 41
Views: 5,399
Posted By mc6809e
Your interrupt handler looks like it checks for...

Your interrupt handler looks like it checks for the possibility of another interrupting event. Are there other events that cause an int3 like the blitter? If other int3s are possible, what happens to...
Forum: Coders. Asm / Hardware 01 April 2022, 19:08
Replies: 41
Views: 5,399
Posted By mc6809e
How much time does your vblank int handler take?...

How much time does your vblank int handler take? Is it being delayed excessively by frequent lvl 6 ints generated by the player?

Have your vblank handler change the background color at the very...
Forum: Coders. Asm / Hardware 08 March 2022, 00:34
Replies: 8
Views: 1,419
Posted By mc6809e
How about a default global seed that sets random...

How about a default global seed that sets random disk position, timer values, etc on start up with an option for the user to manually provide a different seed?
Forum: Coders. Asm / Hardware 07 March 2022, 01:12
Replies: 22
Views: 3,402
Posted By mc6809e
The bitplane organization in the ST has some...

The bitplane organization in the ST has some advantages when using the CPU for 16 color graphics. A pair of MOVE.Ls will update 16 pixels while on the Amiga four MOVE.Ms are required, one for each...
Forum: Coders. General 26 February 2022, 02:24
Replies: 20
Views: 5,136
Posted By mc6809e
Yeah, there were several games that used the WCS...

Yeah, there were several games that used the WCS as fast RAM. Dragon's Layer was one I think.

I was referring to kickstart code in ROM, on the A500, for example.
Forum: Coders. General 25 February 2022, 16:34
Replies: 20
Views: 5,136
Posted By mc6809e
Here's a question: if VPOS is written to, can we...

Here's a question: if VPOS is written to, can we fool the hardware into generating a vertically longer display by resetting VPOS to an earlier line? My guess is yes to some extent, but a CRT would...
Forum: Coders. General 25 February 2022, 15:13
Replies: 20
Views: 5,136
Posted By mc6809e
I was under the impression that the LOF bit in...

I was under the impression that the LOF bit in VPOSw could be written to and that if LACE was off in BPLCON0 LOF would not toggle.



Even a tiny bit of static RAM just for the CPU would been...
Forum: Coders. Asm / Hardware 24 February 2022, 14:30
Replies: 32
Views: 3,951
Posted By mc6809e
Are your modulo values correct? If your width is...

Are your modulo values correct? If your width is one word less then the modulo value must be increased by one (assuming the source is stored as a rectangular bitmap).
Forum: Coders. Asm / Hardware 24 February 2022, 02:16
Replies: 32
Views: 3,951
Posted By mc6809e
Pretty much. Of course that also determines how...

Pretty much. Of course that also determines how many words will be read from the source whether the source in terms of actually used bits is really that wide or not, hence the need to.pad the source....
Forum: Coders. Asm / Hardware 23 February 2022, 19:27
Replies: 32
Views: 3,951
Posted By mc6809e
The width is determined by the needs of the...

The width is determined by the needs of the destination and not by the source.

Even a two-pixel-wide source will need an extra word on each line if there is any possibility that the blitter will...
Forum: Coders. Asm / Hardware 15 February 2022, 06:17
Replies: 338
Views: 387,845
Posted By mc6809e
I've been trying to figure it out, too. The chips...

I've been trying to figure it out, too. The chips are NMOS devices so the anding is easy to explain. If many gates have their outputs tied together then if any gate outputs low then the line goes...
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