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ZX Spectrm Emulation on Atari 1200 XL


Poison
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Damn that's impressive...Shame about the high hardware cost needed but still damn impressive..

 

Looked and sounded like one of the Romanian guys that did my flat up over the last 3 weeks :)

 

Congrats to the creators of that emulator(?), great to see the old Atari doing special stuff :)

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Congrats to the creators of that emulator(?),

So, let's greets to Konrad Kokoszkiewicz, aka KMK aka Drac030 ;) But, unfortunately - on real Atari (6502C, no Rapidus (or other 65816) and no VBXE this emulator won't run :(

Edited by Sikor
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I was really impressed how many of the games we downloaded actually work, and how easy the usage of "Lets Emu!" is.

This is really a good showcase of how to put a Rapidus+VBXE equipped machine into use...

 

The 1200XL was running completely stable all weekend...

 

Thanks to the developers of all this impressive new hardware upgrades. And still, i can switch everything back to normal

6502c, load a GTIA core and have a stock machine experience.

 

 

Greets,

Beetle

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It is the stock FX core. The display itself is generated by ANTIC, the VBXE is used to add colors by means of the color map. The conversion of the color attributes from the ZX Spectrum format to the VBXE format is being done by the blitter, so it practically does not engage the CPU.

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What about the game code? Is it by emulation or is it like other ports as in sit down and painstakingly translate line by line Z80 to 6502?

I would have thought that even at 14 MHz there'd be massive slowdown... something like 3 times that speed again might be needed to equate to a 3.6 MHz Z80.

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The Z80 is emulated in software, a 20 MHz 65C816 is good enough to do the job so that most programs work well. EDIT: of course, the emulation is not cycle-exact, but it anyways turns out to be good enough in most cases.

 

Those which do not work, fail mainly because of the Z80 R register not being emulated. I already have a version which emulates the R too, but it is a bit slower, so in future releases I will probably provide two separated binaries.

 

Also TAP files which contain custom tape loaders will not load.

 

I am glad that people find the program interesting, thanks for the nice words :)

 

As about putting the Rapidus+VBXE into use, I have to add that the program itself was written and is being developed not on a PC, but on my "unreal Atari" (320k 65XE, Rapidus, VBXE, IDE+). :)

Edited by drac030
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Sure. It is a question of defining a generic CP/M machine and writing a BIOS for it. Then I could convert the existing ZX Spectrum emulator into a CP/M emulator.

I have the BIOS source code for porting to new machines somewhere.

I think it came from this link:

http://compgroups.net/comp.os.cpm/computer-history-museum-cp-m-source-code-release/2999215

 

And some info on CP/M that might help.

http://obsolescence.wixsite.com/obsolescence/cpm-internals

 

Then it's a matter of some terminal emulation for the screen.

The 64 column text code I wrote for the Atom could be adapted to the Atari for 80 column support if you are interested.

I started work on Atari and Plus/4 (C64?) ports but haven't gotten around to finishing them yet.

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@JamesD Thanks for the links. As for the terminal, we already have a terminal for the Indus CP/M - namely TT (aka Trub's Terminal). It is a question of reusing its code.

 

Of course, there is nothing difficult in making the BIOS running the native code. It is enough to setup a trap which will switch the execution between the emulated Z80 and the host CPU. The BIOS would have to do that anyways, to use the functions of the underlying OS and e.g. access the hard disk.

Edited by drac030
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I am under the impression that CP/M FS emulation would only be needed if we wanted to replace also the BDOS with the native code. It may of course be profitable, but I think it is better to start off something simpler, i.e. just replace the BIOS and see how things work.

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I am under the impression that CP/M FS emulation would only be needed if we wanted to replace also the BDOS with the native code. It may of course be profitable, but I think it is better to start off something simpler, i.e. just replace the BIOS and see how things work.

Well, I think mounting disk images is more important than reading/writing physical disks.

 

*edit*

For compatibility testing I think Wordstar and Visicalc would be the first choices.

Edited by JamesD
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