ZX81X2.ROM - and the big bang

[Moggy]

Slips in quietly...

...... look here ......

I’ve got a diagram somewhere, but that’s buried in a pile of notes....

Exits stage right...

Mark

Except please ignore the over complex wiring diagram I provided as it is now found to be complete bollux!

[Trevor_B]

Thanks to both of you - for the information and the amusement!
Trev

[kmurta]

Hi guys!

I leave here the ROMs for the ZXpand and ZXpand+ upgraded for the big bang ZX81x2c. I have v66x2c installed and tested on my ZXpand (as can be seen here), but v72x2c was only tested on the EightOne emulator.

Note that the ZXpand ROM version number was moved from address 7679 to address 2273. Likewise, the ZX81x2 FW_ID was moved from addresses 37, 38 and 39 to addresses 2270, 2271 and 2272 (day, month and year, in hex format).

zxpandv66x2c.zip

For ZXpand classic

(74.61 KiB) Downloaded 146 times

zxpand+v72x2c.zip

For ZXpand+

(74.83 KiB) Downloaded 150 times

Edit 15/07/2024: fixed zxpand+v77x2c ROM

[Moggy]

Hi Kelly!

Not sure what this is for and what to do with them. Are you supposed to burn them to a chip and replace the one on the ZXpand or plug them into the Zeddy socket? What do they have over the older X2 ROM?

[kmurta]

What do they have over the older X2 ROM?

This is the old X2 ROM with the ZXpand routines added. The intention is to rewrite the ZXpand EPROM and thus have access to the Big Bang features without having to change the ZX81's internal ROM. Personally, I prefer this configuration; when I need to run some software that requires the internal ROM (i.e. pseudo-HR), I just disable the ROM overlay.

[Moggy]

Ah so burn the image to a 2764 EPROM of which I have many ( as found on the classic ZXpand) then replace the one on the spand and off we go?
I assume also that the new spand ROM references the character table in the main onboard ROM?

If so I know what I'll be doing tomorrow!

I did try the ROM in Eighty One and just got a screenful of garbage so not sure what happened there.

[kmurta]

I assume also that the new spand ROM references the character table in the main onboard ROM?
Ah so burn the image to a 2764 EPROM of which I have many ( as found on the classic ZXpand) then replace the one on the spand and off we go?

Yes

I did try the ROM in Eighty One and just got a screenful of garbage so not sure what happened there.

You need to replace the overlay ROM (zx81.zxpand.ovl) with the new ROM. To do this, rename the file zxpand+v72x2c.rom to zx81.zxpand.ovl and copy it to the ROMs directory in the EightyOne folder.

[Moggy]

Thanks Kelly I did rename it and still got garbage. I will try this on another machine with a fresh install of Eighty One and also burn a new EPROM tonight. My classic spands have the AY unit fitted but I don't think this makes a difference.

[Moggy]

No luck I'm afraid as this is what I get with the renamed ROM in Eighty One.

[Moggy]

Found the solution!

v72x2c causes the garbage for me in Eighty One but v66x2c works however CONFIG "X" causes a whiteout, I tested it to see if the "PAUSE" stutter was present after a screenful of CHR$ was SCROLLED and no stutter present and the CLS cleared the screen instantly so looks like the improved features are there and can't wait to try this on my real spands and will report back with results.


Nice work Kelly, thanks for this.