Banked Video RAM?

[McArti0]

Actual documentation.

Please note:
1) After programed IC we must re-solder all pins upside down.
2) We nead jumper Pin6-Pin2 (A14out)
3) PullUp resistor circ. 3.3k for Pin9 (A15out) or use jumper Pin7 to Pin9 (Pin7 alternative A15out without pullup needed)

Cost:

SLG46533v-DIP
https://au.mouser.com/ProductDetail/Renesas-Dialog/SLG46533V-DIP?qs=w%2Fv1CP2dgqrHSB6MtY%2FTdA%3D%3D

7.94 AUD  4.56 EUR

programmer
https://au.mouser.com/ProductDetail/Renesas-Dialog/SLG4DVKDIP?qs=rkhjVJ6%2F3ELLCgcET%2Fycrw%3D%3D

60.75 AUD  36.27 EUR

[McArti0]

Mainboard foto for check conections PAL IC

[McArti0]

Prototype SpiderMonster without soldering.   The keyboard doesn't press on this monster.

First time closed CPC6128 and NewPAL inside.

I pressed the goldpins with a soldering iron to half their length.

It turned out that the VRAM banks toggler works when there are 0-4 nops between OUT instructions.

LD BC,&7FC0
OUT (C),C
nop:nop:nop:nop
OUT (C),C

Becauce CNT3/DLY3 in GreenPAK IC has counter data 5

[McArti0]

https://youtu.be/KeRK6TgyeoA

[HAL6128]

Is this mod "downward" compatible?

[McArti0]

Yes. One hundred percent.

CPM works, Batman Forever works.

Trigger toggler is based on the assumption that no software changes rambak settings twice in succession.

Therefore it is a typical PAL with a hidden feature.

You can of course remove the NewPAL and insert the original black PAL.

ps. I also thought about Trigger toggler when writing OUT &BXxx,&Cset, i.e. in conflict with CRTC, but it seemed too risky to me.

[zhulien]

I would like to try with my current memory access functions. If the quick succession has to be very very quick I.e. 4 nope or less between then likely no compatability issues but if a bit more I need to test and perhaps fix my code if only my code is an issue.  I'm think still corner cases when i do a far call to main ram from main ram and immediately return, but perhaps my code shouldn't actually hit the GA if I aren't actually changing banks... 

A couple of possible uses all of which RSXs could be created.

- A set of x400 interlaced modes, would it work nicely on modern LCDs without flicker? 

- Full screen animation player with streaming from sdcard but multiple full screen buffers so the loading can be staggered between frame flips so that it is averaged out to get a constant full screen LONG animation.

- perhaps overscan basic mode. I would like to use this.

- my MOS i was only going to have text modes plus 1 graphics mode, with drivers etc in banks.  If screens can now be in different banks, then it might be more trivial to control+1 or control+2 to swap between completely different basic instances.  If it does support more than 128k then we could perhaps have more instances of basic.  Why?  You never wanted to quickly do something else in the middle of your programming without having to exit what you are doing?  Whether multitasking or not it is useful.

[McArti0]

I would like to try with my current memory access functions. If the quick succession has to be very very quick I.e. 4 nope 

4 nops is negotiable. We can change the design and set a different value. The first prototype currently in existence has 4 nops. It may have a different value.

- A set of x400 interlaced modes, would it work nicely on modern LCDs without flicker? 

All EGA and similar modes with Hsync since 14,5kHz Vsync 25-40Hz WITHOUT interlaced and Vsync 40-60Hz WITH interlaced. (720x480p@30 as 1024x480, 720x480i@60 as 960x480 e.t.c.)

- perhaps overscan basic mode. I would like to use this.

BUT several solutions are possible with unmodded CPC.

- my MOS i was only going to have text modes plus 1 graphics mode, with drivers etc in banks.  If screens can now be in different banks, then it might be more trivial to control+1 or control+2 to swap between completely different basic instances.  If it does support more than 128k then we could perhaps have more instances of basic.  Why?  You never wanted to quickly do something else in the middle of your programming without having to exit what you are doing?  Whether multitasking or not it is useful.

The problem is that standard RAM expansion overshadows the second internal RAM bank. We can't to write to second bank internal RAM.

[zhulien]

Maybe then... we can flip it over so basic is running from the 2nd bank and video ram has almost a full 64k in the primary bank. This is worth experimenting with.

[McArti0]

We need expansionRAM adapter to deshadowed 64kB

[McArti0]

Adapter deshadower for 512kb ExpRAM. I think this may be enough.

 Link to simulate Deshadower

[McArti0]

Or maybe like this? : Link deshadower v2