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Tezxas ZX Spectrum Emulator v2.1
Posted by Nick on 3 September 2000, 00:54 GMT

I think that some guy by the name of Samir Ribic released Tezxas ZX Spectrum Emulator v2.1 for the 89 and the 92 Plus. I've always been a big fan of Samir's work in getting the ZX Spectrum games to work on the calculator; it's a prime place to show that sort of thing off, and porting old-school games to a platform suited to play old-school games just seems very fitting. :) Many bugfixes and AMS v2.0X support accompany this new version. Added zoom keys also exist. You can grab a bunch of Tezxas games and such at this page at the present moment. Good job to Samir on getting this version as stable as he possibly can: his efforts are much appreciated.

 


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Re: Tezxas ZX Spectrum Emulator v2.1
Samir Ribic  Account Info
(Web Page)

Last night, I discovered why Fist II legend continues has damaged scroll routine, so number of redlighted programs will be reduced by 1 in next release.

     3 September 2000, 09:25 GMT


Re: Re: Tezxas ZX Spectrum Emulator v2.1
Scott Noveck  Account Info
(Web Page)

Bah, I don't see why grayscale is forbidden on HW2 calcs - contrary to popular opinion, HW2 grayscale programs do NOT run significantly slower than HW1 grayscale, they simple flicker more.

Samir, even though HW2 grayscale would require a few extra clocks, the chip in HW2 calcs is a TWELVE MHz 68k, as opposed to the TEN MHz in HW1 calcs (see TI's FAQ for confirmation). We discuss the issue every once in a while on the A89 mailing list, and the most recent conclusion is that HW2 grayscale will still be a bit slower, and the graphic quality will be reduced, but it's not unreasonably slow.

Besides, adding in the option to have HW2 grayscale doesn't really hurt - the user can choose how (s)he wants the program run and whether the speed sacrifice is worthwhile.

     3 September 2000, 09:50 GMT

Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Paulo Marques  Account Info

ditto

     3 September 2000, 19:05 GMT

Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Thomas Nussbaumer  Account Info
(Web Page)

The reason why grayscales on HW2 calculators may slow down some programs is that on HW2 calculators the WHOLE screen content must be copied for a plane switch. On HW1 calculators just an other address pointer must be written to a port.
And copying 2-4kB very often per second will last some time.
But most programs don't keep the processor busy. So the decrease in speed is not recognizable.

     4 September 2000, 15:10 GMT


Re: Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Samir Ribic  Account Info
(Web Page)

Tezxas is very rarely in idle, because it emulates CPU and updates picture. HW2 grayscale will give it additional screen update. First convert ZxSpectrum image to TI89 bitplanes, and then put bitplane to screen.

I remember first version of tezxas that worked, screen was updated 50 times per second, as in Spectrum. After I reduced to 5 times per second, I had twice faster program.

     4 September 2000, 16:48 GMT


Re: Re: Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Scott Noveck  Account Info
(Web Page)

> First convert ZxSpectrum image to TI89
> bitplanes, and then put bitplane to screen.

Then you'll already halfway there. . . copying from bitmap to screen only takes about 13,000 clocks if done correctly (optimized with movem, etc) - see my HW2 grayscale source. This is sufficiently fast running every fourth call of auto-int 1 (or every call of auto-int 5), which runs at about 375 Hertz.

Therefore, the grayscale copying takes 13,000 * (375/4) = 1,218,750 clocks per second. HW2 calcs are 2 MHz faster, while the HW2 grayscale only slows it down 1.2 MHz.

The result is that HW2 GRAYSCALE IS STILL FASTER THAN HW1 GRAYSCALE! It might flicker a bit more, and the CPU won't be idle as often, but speed is a poor excuse for not implementing it.

And the 13,000 clocks is for copying the _entire_ screen buffer, on the 92+. I can do a mere 11,600 clocks on a HW2 89.

I rest my case - stop listening to all this crap about HW2 grayscale being slower and go implement it - I wanna play purdy Tezxas games =)

     4 September 2000, 18:34 GMT


Re: Re: Re: Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Samir Ribic  Account Info
(Web Page)

You are right. I changed grayscale routine to copy page instead flip and tested Manic miner, how much time it needs to stay without air:
Original Spectrum 2'20"
HW1 style grayscale 4'38"
HW2 style grayscale 5'18"
Fast mode 3'48"

Manic miner is not synchronised with interrupt. The games syncronized with interrupt are almost as fast in all cases.
Well, it is slower on HW 2, but not as I was afraid. (Un)fortunantely, I have not HW2 calculator. I can send you version of Tezxas I suppose works with grayscale on HW2 and you can try it. Also, I need reliable method to recognize HW release (I think Julien knows many).

     5 September 2000, 00:33 GMT


Re: Re: Re: Re: Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Samir Ribic  Account Info
(Web Page)

Ah yes, now I tried grayscale Tezxas on real HW2, now grayscale Manic miner test is 3'16", fast mode 2'28".

     12 September 2000, 09:34 GMT


Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1
Zeljko Juric  Account Info
(Web Page)

There is a problem - Tezxas requires 7-level grayscale, not 4-level one. Maybe I am wrong, but I don't know that an usable 7-level grayscale routine even exists for HW2...

     4 September 2000, 21:18 GMT

Re: Tezxas ZX Spectrum Emulator v2.1
DWedit  Account Info
(Web Page)

Too bad I no longer have my TI89!

I suggest a feature for the TI89 version: draw every fourth pixel from the 2x2 shrink each frame, would that improve or worsen the graphics?

     3 September 2000, 18:14 GMT


Re: Re: Tezxas ZX Spectrum Emulator v2.1
Samir Ribic  Account Info
(Web Page)

If you think to choose one pixel of four, similar option already exists /lu or /ld. Cycling of pixels in every frame is interesting idea, but can be too flickery or too memory requesting.

     3 September 2000, 18:39 GMT

Tezxas ZX Spectrum Emulator v2.1 won't work
ksi

I'm have a calc with HW 2 and ASM 2.5. Why won't it work with my calc.

     4 September 2000, 19:02 GMT


Re: Tezxas ZX Spectrum Emulator v2.1 won't work
Samir Ribic  Account Info
(Web Page)

Currently it (I hope) works without grayscale on such combination. Do not forget to archive Tezxas, srom and snapshots. Start game with asterix prefix
tezxas("*fred")
If still does not work, I need to borrow one HW2 calc.
Next release will have grayscale on HW2 too.

     6 September 2000, 09:29 GMT


Re: Re: Tezxas ZX Spectrum Emulator v2.1 won't work
Jared B  Account Info
(Web Page)

I have a HW 2.00 and the program crashes whenever I use it. I have utilized the alternate commands (Tezxas"*fred")) but it still does not work. Any suggestions?

Jared

     8 September 2000, 23:34 GMT


Re: Re: Re: Tezxas ZX Spectrum Emulator v2.1 won't work
Samir Ribic  Account Info
(Web Page)

If you have not archived files tezxas and srom, then there are yet some problems with HW2. Zeljko borrowed HW2 from one student girl and I will try something.

     9 September 2000, 00:41 GMT

Re: Tezxas ZX Spectrum Emulator v2.1
Sérgio Gomes  Account Info
(Web Page)

Thankx for creating this OS!

     5 September 2000, 00:23 GMT

Re: Tezxas ZX Spectrum Emulator v2.1
Sérgio Gomes  Account Info
(Web Page)

Thankx for creating this OS!
I have already 'Hacked' it,but i want to know more.
BEE goog and release the source.

TI92plus on irc.net


     5 September 2000, 00:25 GMT


Re: Re: Tezxas ZX Spectrum Emulator v2.1
Samir Ribic  Account Info
(Web Page)

Source will be released after receiving POTM award, whenever this be. I must say, however, it is not example of structured programming. All routines are divided in 30 bytes long chunks with dozen of jump instructions, self modify code, even position dependant, but it is as fast as possible.

     6 September 2000, 08:53 GMT

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