Possible bug in ZX81x2 ROM ?

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Moggy
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Possible bug in ZX81x2 ROM ?

Post by Moggy » Mon Oct 22, 2018 8:17 pm

Whilst flipping through various programs to test the ROMS speed I came across an anomaly with a game called "Em busca Dos Tesouros" (In search of Treasure)

Although a mainly M/C program I thought it worth trying, if only to get through the tiresome intro screens, only to find that when the final menu screen comes up, the 81 crashes(back to BASIC) when using the new fast ROM yet is playable with either the original ROM or the xpand ROM.(tested on three separate 81's with both original ULA's and the new ULA)

I also tried this in Eighty One (v 1.6 and 1.7) and the screen is unreadable/unplayable with the fast ROM although it doesn't crash like the real thing which I put down to the same kind of quirks that Eighty One exhibits with for example the H4th ROM inverse screen routine, namely one thing happens with real kit and another by said emulator.


As a non games player this doesn't really concern me but may affect those who are. Here is said game for those of you who may have created their own ZX81x2 EPROM and would like to observe the effect and perhaps try and understand what's going on.


LATE EDIT.

It's not too happy with this demo either (missing graphics).
Attachments
RDEMO3.P
(13.18 KiB) Downloaded 35 times
EBP.P
(15.79 KiB) Downloaded 33 times

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zsolt
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Re: Possible bug in ZX81x2 ROM ?

Post by zsolt » Tue Oct 23, 2018 12:24 am

Hi Moggy,

I just tried these programs w. EO (v1.2), both need sram in 8-16K region.
The game did not work well also with the old rom. :o
In the SHREB-demo the fill instuction does not work indeed - i will look.

Regards,
Zsolt
ZX81 (8K), ENTERPRISE 128, [ZX SPECTRUM (48K,+,+128K,+2,+2A), TS1000, TS1500, TS2068, Cambridge Z88, PRIMO A64 (red)]

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kmurta
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Re: Possible bug in ZX81x2 ROM ?

Post by kmurta » Tue Oct 23, 2018 4:24 am

Hi Moggy!

Is there a problem with your copy of EBDT, try this one:

Tesouros.p
(15.45 KiB) Downloaded 53 times
1 x ZX81, 2 x TK85 , 1 TK82C, 1 TK95, 1 x Ringo R470, 1 x Alphacom 32 printer, 1 x ZXpand
ZeXtender board, Joy81 - Programmable Joystick Controller, Turbo Sound 81
http://zx81.eu5.org

Moggy
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Re: Possible bug in ZX81x2 ROM ?

Post by Moggy » Tue Oct 23, 2018 12:24 pm

Hi Kelly.

Thanks for this, but no the problem seems to be the ROM code. I have tried a few more hi-res demos and the graphics are corrupted when using this new ROM and I imagine some other programs may suffer also.

I use real ZX81 not emulator and the game and the demos are ok when using the original ZX81 or ZXpand ROM but show some corruption with the ZX81x2 ROM.

This is not an issue for me as I'm a very simple BASIC programmer but for those of you who are M/C programmers this may be a problem.


Best Regards.

Moggy.

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kmurta
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Re: Possible bug in ZX81x2 ROM ?

Post by kmurta » Tue Oct 23, 2018 2:36 pm

I understand, but I tried your EBP.P file in the EO 1.12 with old ROM and with ZX81x2 ROM and it failed in both cases.

However, the Tesouros.p run fine with both ROMs.
1 x ZX81, 2 x TK85 , 1 TK82C, 1 TK95, 1 x Ringo R470, 1 x Alphacom 32 printer, 1 x ZXpand
ZeXtender board, Joy81 - Programmable Joystick Controller, Turbo Sound 81
http://zx81.eu5.org

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zsolt
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Re: Possible bug in ZX81x2 ROM ?

Post by zsolt » Tue Oct 23, 2018 3:33 pm

Hi,
Moggy wrote:
Tue Oct 23, 2018 12:24 pm
Thanks for this, but no the problem seems to be the ROM code. I have tried a few more hi-res demos and the graphics are corrupted when using this new ROM and I imagine some other programs may suffer also.
:o
Which programs are affected? It would be good to know, because it would be easier to find the mistake.
kmurta wrote:
Tue Oct 23, 2018 2:36 pm
I tried your EBP.P file in the EO 1.12 with old ROM and with ZX81x2 ROM and it failed in both cases.
As i experienced.

Thanks,
Zsolt
ZX81 (8K), ENTERPRISE 128, [ZX SPECTRUM (48K,+,+128K,+2,+2A), TS1000, TS1500, TS2068, Cambridge Z88, PRIMO A64 (red)]

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siggi
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Re: Possible bug in ZX81x2 ROM ?

Post by siggi » Tue Oct 23, 2018 3:48 pm

Moggy wrote:
Tue Oct 23, 2018 12:24 pm
HI have tried a few more hi-res demos and the graphics are corrupted when using this new ROM and I imagine some other programs may suffer also.
Caution: Pseudo-Hires pictures are based on the "pixel" patterns in ROM, which are used to generate the (pseudo) hires display. Thus their display will look different, because the ROM, which is base for that displayed pixels, is now different.

Only true hires displays (like WRX) should show the same hires picture .

So please check, if those programs, which show different hires pictures, use true or pseudo hires ...

Siggi

Edit: Addendum: true hires games will loose the hires screen, if WRX is diabled at EO. Pseudo hires displays will still show the pseudo hires screen (at least in theory ;) )
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Moggy
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Re: Possible bug in ZX81x2 ROM ?

Post by Moggy » Tue Oct 23, 2018 8:46 pm

siggi wrote:
Tue Oct 23, 2018 3:48 pm
Moggy wrote:
Tue Oct 23, 2018 12:24 pm
HI have tried a few more hi-res demos and the graphics are corrupted when using this new ROM and I imagine some other programs may suffer also.
Caution: Pseudo-Hires pictures are based on the "pixel" patterns in ROM, which are used to generate the (pseudo) hires display. Thus their display will look different, because the ROM, which is base for that displayed pixels, is now different.

Only true hires displays (like WRX) should show the same hires picture .

So please check, if those programs, which show different hires pictures, use true or pseudo hires ...

Siggi

Edit: Addendum: true hires games will loose the hires screen, if WRX is diabled at EO. Pseudo hires displays will still show the pseudo hires screen (at least in theory ;) )
I think siggi has solved the hi-res demo question perfectly :geek: , if the bits are now not where they once were they cannot be printed which is a small price to pay for a few trivial demos. The faster BASIC more than makes up for this. :D

As for the game Kelly is absolutely correct, the version he supplied (Tesouros.p) works ok on real 81 with new ROM but the EBP.P version only works with old ROM so I don't know what's happening here. :?

It would take some one with a better brain than mine to check the code in both examples of the game and see if anything is different but that doesn't answer the question of why it works on real 81 with old ROM.

If I come across any more game/program examples I will post here but I suspect it will only be the pseudo hi-res programs/demos that would exhibit this phenomenon and so be of no importance.


Regards.

Moggy.


LATE EDIT.

Just tried a few WRX hi-res examples and can now confirm what Siggi said to be correct, only the pseudo hi-res examples don't work and the WRX stuff is all ok as he predicted.

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siggi
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Re: Possible bug in ZX81x2 ROM ?

Post by siggi » Wed Oct 24, 2018 9:07 am

Moggy wrote:
Tue Oct 23, 2018 8:46 pm
Just tried a few WRX hi-res examples and can now confirm what Siggi said to be correct, only the pseudo hi-res examples don't work and the WRX stuff is all ok as he predicted.
Hi Moggy,
that problem only occurs, if the ZX81x2 rom is run internally inside the Zeddy (or on EO). If it is connected externally (e. g. using such an external rom card http://forum.tlienhard.com/phpBB3/viewt ... 838#p37240 or sometimes maybe ZxPand), the external rom is switched off during REFRESH cycles (to allow the Z80 access to the character generator in internal rom to generate the display). Thus also pseudo hires programs will access the internal (original) rom/bit patterns during display of the pseudo hires screen.

Siggi
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http://zx81-siggi.endoftheinternet.org/index.html

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siggi
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Re: Possible bug in ZX81x2 ROM ?

Post by siggi » Thu Oct 25, 2018 11:47 pm

zsolt wrote:
Tue Oct 23, 2018 12:24 am
In the SHREB-demo the fill instuction does not work indeed - i will look.
Hi ZSOLT
maybe a consecutive fault: the SHREB demo stops at line 1000 with error "B/1000".

Siggi
My ZX81 web-server: online since 2007
http://zx81-siggi.endoftheinternet.org/index.html

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