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Tezxas - ZX Spectrum Emulator for 89
Posted by Nick on 29 September 1999, 23:24 GMT

Samir Ribic, previously unknown to the TI community, has released an interesting program called Tezxas for the TI-89. This program allows you to emulate ZX Spectrum programs on the 89. It comes with some samples, too. Don't know what the ZX Spectrum is? Click here for more information. It's easy to port these programs to the 89; the documentation in the program helps explain how. This is reminiscent of when the Chip8/SChip8 emulators were released for the 92, the 92 Plus and the 85.

 


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Re: Tezxas - ZX Spectrum Emulator for 89
DWedit  Account Info
(Web Page)

Will there ever be state saving? It would be nice to be able to stop playing and continue later.

     30 September 1999, 23:35 GMT

Re: Tezxas - ZX Spectrum Emulator for 89
elohEEm  Account Info
(Web Page)

I heard somewhere that the ZX spectrum used a slow z80 processor. (Please correct me if this is not true) If this is the case, then isn't this emulator also emulating the z80 in some way? If so, shouldn't emulating a z80 calc be a bit easier?

--Aaron

     1 October 1999, 02:54 GMT


Re: Re: Tezxas - ZX Spectrum Emulator for 89
S67  Account Info
(Web Page)

Especially since the calculator have smaller screen, no greyscale(except for mario 86), no sound,and no key remaping. shouldn't ti be a ton easier, and almost to fast? this emulator reduces the display 4x real time, so it is very good for what it does. the calcultor should be easier.

     1 October 1999, 04:45 GMT


Re: Re: Re: Tezxas - ZX Spectrum Emulator for 89
prabal  Account Info
(Web Page)

hey could somebody start a page with the best games which are already converted and look good on a 89? thatll be great, plus the games with the zip file sux big time.

     1 October 1999, 16:51 GMT

Re: Tezxas - ZX Spectrum Emulator for 89
PSInferno  Account Info

Excuse me for such a stupid question, but didn't the ZX Spectrum run using a Z80 CPU? Doesn't that mean that TI-8X emulation could be possible on the TI-89, with some changes?

     4 October 1999, 01:18 GMT

Re: Re: Tezxas - ZX Spectrum Emulator for 89
DWedit  Account Info
(Web Page)

Yeah, but TI8X's have a fast Z80. (6mhz, overclockable to 20mhz) Try a 2 mhz system, one with games such as pokémon, and super mario land 2, as well as kirby. You know which machine I'm referring to, TI's biggest rival in the games dept. Nintendo gameboy. There's already NO$GMB for PC, and it runs pretty fast on a 286, even playable speed on an 8088. Why not Game Boy on TI89? Why emulate Joltima on an 89 when one could emulate Pokémon?

     4 October 1999, 03:13 GMT


Re: Re: Re: Tezxas - ZX Spectrum Emulator for 89
prabal  Account Info
(Web Page)

yeah, a gameboy will be better emulated because it has a smaller screen (resolution) so somebody anybody get the fuk up (Limp bizkit rulez) and maake it!

     4 October 1999, 17:06 GMT


Re: Re: Tezxas - ZX Spectrum Emulator for 89
Samir Ribic  Account Info
(Web Page)

There are two problems. All Z80 based TI calculators are 6 MHz. Keep in mind that currently, emulating 3.5 MHz Z80 I reached the speed of 25-80% of the original.
This means that emulating of 6 MHz Z80 will in start mean 15-80% of the original (upper limit only for programs synchronized with interrupt).

Even worse, all TI-8X (X<8) calcs have ROM bigger than 32 K. That means page swapping. This is very time consuming operation that can put lower limit to 5%, unless someone rewrite ROM to avoid often swapping of ROM.

The other two machines I think about are ZX81 and general CP/M machine. The games for those machines were ugly, but speed can be closer to the original.
The games for those two machines

     6 October 1999, 16:23 GMT


Re: Re: Re: Tezxas - ZX Spectrum Emulator for 89
Sparky009 Account Info

Well, first off, this is a great emulator (believe it or not). It is hard to write an emulator (at least IMHO). If the GB is truely a 2MHz z80 chip, and the speed of an emu of a z80 3.5MHz chip is in the range of %25-%80, then shouldn't a GB emu be somewhat practical? The only reason I can see it as not is if the size of the games exceeds the mem of the calc. To my knowledge, most regular GB emus (NO$, DBoy, happyGB) don't require rom images. Perhaps this would be something to look into?

     7 October 1999, 04:50 GMT

Re: Re: Re: Re: Tezxas - ZX Spectrum Emulator for 89
DWedit  Account Info
(Web Page)

ALL GB emu's need ROMs, not necessarly commercial though.

     7 October 1999, 05:41 GMT


Re: Re: Re: Re: Tezxas - ZX Spectrum Emulator for 89
Samir Ribic  Account Info
(Web Page)

I have source of CPU core of one GB emulator for Amiga. The concept of this emulator is very similar to TEZXAS (64 K of the position dependant code), but my decoding of instructions is twice faster.

GB processor is not Z80, although very similar. About 20 instructions are different (mainly, GB has no I/O instructions).

However, I do not know anything about hardware of GB, and sometimes it can be bigger problem than Z80 itself.

     7 October 1999, 09:21 GMT

Re: Tezxas - ZX Spectrum Emulator for 89
Robbie Rothermel Account Info
(Web Page)

Alright, two questions...

One, why not ask for help with building a GB emulator from somebody who actually built a pc GB emulator. I know the guy who built the NO$GMB actually did his emulator in assembly code. Maybe this isn't a good idea, but it's my 2¢...

Also, the GB has a C compiler that I've used before. It's very easy to use, though it is a command-prompt compiler. But there is another factor to consider when doing a GB emulator for the TI. Ever seen the size of a GB game? All GB games size's are multiples of 32k. In other words, small games (like, no grfx) are 32k, exactly. Then comes 64k games, but most actual GB games are 128k. You'd probably only be able to fit one GB ROM on the calc at a time. I'd like to see a GB emulator for the calcs too. I think we'd also have to build a stripper that removes blank space (made by each cartridge having the size a multiple of 32k), so that the files would be smaller.

Second question, any ideas on how to get the Chip8 emulator work on my TI-92+? The screen is all messed up (I think it's due to the ROM not supporting it or something...same thing happens with some text viewers).

Thanks!

     7 October 1999, 15:16 GMT

Re: Re: Tezxas - ZX Spectrum Emulator for 89
prabal  Account Info
(Web Page)

go ahead make the emulater. it would be grat and id love to help. it souldnt be that hard

     7 October 1999, 16:55 GMT


Re: Re: Tezxas - ZX Spectrum Emulator for 89
Samir Ribic  Account Info
(Web Page)

I think that the ideal man will be
Ville Helin vhelin@cc.hut.fi
from Finnland, because he wrote GB
emulator for 68000 based machine. (Commodore Amiga)

I found somewhere on net part of his source (gbZ80 core), with remark

" You may not use any parts of this source file in any way. Copying, altering, renaming, etc. touching and distributing this file afterwards is illegal and prohibited."


So, if someone wants to get in touch with him ...

     8 October 1999, 00:01 GMT
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