"Aleste 520EX" - does anyone ever heard about this computer??

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By PingPong

Prophet (3889)

PingPong's picture

06-08-2006, 16:49

There is only one problem for true emulation: Z80 has no hardware which let redirect all hardware access to software subrotine! Another problem is speed. I believe that 30-40MHz of z80 plus fast DDRAM can emulate 100% of VDP and even make it faster that real one. So imagine that Aleste show 12 fps only with 300 ns memory. Whell lets multiply 8MHz to 5 for 40Mhz and increase speed of memoy to 60ns. And it will have 50fps.

Actually there is the problem of relative slowness of the real vdp; it has to use 300ns RAMs.

Even with 300ns rams the vdp is too fast in 512x212x16 and 256x212x256 colors! It need to to address interleaving otherwise the ram chips does not cope with vdp speed. I'm wondering what could be done if enginering in the old days could used 60ns RAM.


Another topic about software tricks like: how VDP containg sprites data and that it is impossible to use LDIR and so on. My answer is simple who said that emulation program should contain sprites information same as VDP? It can insted convert data while CPU send it to VDP. Do not forget that there is "narrow boutle hole" such VDP to CPU interface. Smile

Converting takes time even when sending data; It takes also more memory, and does not forget that msx2 games will stay to the original format. Also even if you get converted data, sprites trasparency emulation does not allow to use ldir! Sad more : you should read and write from vram when doing the sprite plotting to perform masking. the vram layout makes this things estremely hard to do in smaller times, It is possible to do but for a limited amount of moving objects.

See the Amiga. amiga engineers saw the light. they realize that :

HW sprites are to limited (usually their grpx abilities are far inferior respect to static grpx)
SW sprites are better (flex. in size, color and so on), but require to much attention from the CPU (event if they had a 68000 16 bit not the old z80)

What solution?:

The blitter. A sort of HW that manages only that grpx task, freiing the CPU and doing it better and better.!

THIS IS THE SOLUTION, NOT CPU POWERED SW SPRITES.

By Valeriya

Resident (45)

Valeriya's picture

06-08-2006, 17:19

To PingPong
Course it is no way to use LDIR for Aleste. But I do not talking about what and how Aleste does (I do not know actualy) I am just talking about potential way - do not store same as VDP. So what if it take more memory? MSX computer which was popular at that time had only 256KB (128+128Video). Aleste had 512! It was more that enought.
I knew that VDP use interleaved memory access it was common for that age. But you do not right that VDP is fast! It is not. Check it's speed of memory copying operations.

As I can remember ALeste had video mem copying faster that VDP.

Communication VDP-CPU was also slow. Then most games of MSX first send all amount of data to vdp then each frame send small amount for make changes. What is realy good for emulation!

About blitter you are absolutely right. Even w/o memcopying and line drawing I may give allooot! Just pixes setup engine should be more that enought. (Sure with current technologies we could put more that VDP or Blitter to one PLD easy)

It was one of the planes about next of Aleste. There was 3 main ideas at 1993:

1) To make pixel setup engine
2) To use two Z80H CPU
3) To use MGA graphics board

And all of them was rejected - The technologies did not let to designer make it cheap!
Then Aleste 2 project was stopped. Main engineers leave company and company move to PC busines.

By Valeriya

Resident (45)

Valeriya's picture

06-08-2006, 17:27

BTW Aleste 520EX was a first step how to make real MSX clone. It was test. Developer knew that it will not be 100% MSX but people love games and developer choise CPC like base platform. CPC was used only for games. Aleste show that make MSX clone posible. And then should be Aleste 2 which would be 100% MSX and no CPC suport there. Kill CPC compatibility should decrease number of ICs. Then additional ICs shoul be blitter or second CPU or whatewer else for full emulation MSX. But result was not cheaper that 520EX the project was stopeed. Sad

By PingPong

Prophet (3889)

PingPong's picture

06-08-2006, 21:37

To PingPong
Course it is no way to use LDIR for Aleste. But I do not talking about what and how Aleste does (I do not know actualy) I am just talking about potential way - do not store same as VDP. So what if it take more memory? MSX computer which was popular at that time had only 256KB (128+128Video). Aleste had 512! It was more that enought.
I knew that VDP use interleaved memory access it was common for that age. But you do not right that VDP is fast! It is not. Check it's speed of memory copying operations.

I never said it!. It was not fast. What the reason? Not the VDP itself, however the RAM IC. from the vdp point of view it's almost twice fast than IC (In interleaved mode, it reads and put 54*50HzKb every second. So it's fast twice the RAM chips). Copy operations are not fast mainly because of the RAM Chips, not by the vdp itself. If the engineer could had used faster ram chips they can surely achieve better performances.


As I can remember ALeste had video mem copying faster that VDP.

Obviusly! they do not even take in account the bandwidth required to screen buildup that is the most part of work as i said.


Communication VDP-CPU was also slow. Then most games of MSX first send all amount of data to vdp then each frame send small amount for make changes. What is realy good for emulation!

Was not a VDP, but a z80 problem. Outs are very slow. (take 11 to 21 tstates).

Remember that making excellent choices means almost time money.

By DamageX

Master (217)

DamageX's picture

06-08-2006, 22:04

Actually there is the problem of relative slowness of the real vdp; it has to use 300ns RAMs.
300ns?? I think MSX computers generally have 150ns or 120ns chips in them.

See the Amiga. amiga engineers saw the light.
Too bad the Amiga with blitter is still too slow to double buffer 320x200x32colors and acheive 60fps. So it is not suited for shoot'em-ups like... Aleste

By PingPong

Prophet (3889)

PingPong's picture

06-08-2006, 22:19

Actually there is the problem of relative slowness of the real vdp; it has to use 300ns RAMs.
300ns?? I think MSX computers generally have 150ns or 120ns chips in them.

See the Amiga. amiga engineers saw the light.
Too bad the Amiga with blitter is still too slow to double buffer 320x200x32colors and acheive 60fps. So it is not suited for shoot'em-ups like... Aleste

Oh!!, i apologize!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

The VDP is so fast that on 256x212x16colors you can achieve the speed of 6.25fps! Eh!??? Fast as a dead snail!

We msx users will be very happy to have the vdp faster half than the amiga one.!EvilCrazyCrazyCrazyCrazyCrazyCrazyCrazyCrazyCrazyCrazyCrazyEvilEvil

By Valeriya

Resident (45)

Valeriya's picture

07-08-2006, 12:29


300ns?? I think MSX computers generally have 150ns or 120ns chips in them.

Pssible. 13 years pass when I even seen MSX. In any case it have twice less because interleaved memory.

To me amiga's graphics pritty fast. But bitfields not good for graphics editing as still graphics memory. Course for gaming it is defferent.

By PingPong

Prophet (3889)

PingPong's picture

07-08-2006, 12:51


300ns?? I think MSX computers generally have 150ns or 120ns chips in them.

Pssible. 13 years pass when I even seen MSX. In any case it have twice less because interleaved memory.

To me amiga's graphics pritty fast. But bitfields not good for graphics editing as still graphics memory. Course for gaming it is defferent.

bitfields? do you mean bitplane arrangement?

By PingPong

Prophet (3889)

PingPong's picture

07-08-2006, 15:19

@Valeriya: yes bitplane architecture is bad if you think at performances only, because it split the pixel info on multiple banks all at the same address, forcing the access at the same location to be repeated n-depth times for every logic pixel modified in SW).

Of course if you not have any kind of hw support avalilable. Wink

By Prodatron

Paragon (1810)

Prodatron's picture

07-08-2006, 15:31

So is the Aleste 520 on the list of symbos porting? Does a working copy of this machine still exist?

If I get one or if it will be supported in WinApe or blueMSX or another emulator, why not? Wink

I just wonder, if the Aleste would already be able to run SymbOS in CPC mode. As it is something like a clone, it should mean, that there is not much additional work to do. Otherwise a port wouldn't make much sense, as nearly nobody owns an Aleste.

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