ZX81X2.ROM - and the big bang

[kmurta]

What version of EO are you using? The v66x2 ROM is intended for the classic ZXpand, which EO emulates up to version 1.5. From version 1.6 onwards, EO emulates the ZXpand+, so you should use the v72x2 ROM.

[Paul]

I can confirm that my Eightyone 1.40 has the same behaviour as Moggys.
V77X2 just shows ZZZ in every row.

[Moggy]

As promised I have programmed a 2764 EPROM, fitted it to one of my classic spands and yes it works just as it should even the CONFIG "X" command works unlike when I tried it in Eighty One.
So yes works OK and especially useful to owners of issue 3 computers where the ROM is usually soldered to the board. Rather that de-solder that chip and possibly damage things all you needs to do now is burn this new code to a suitable chip for your particular spand and Big Bang goodness can be yours.

Nice one Kelly.

[Moggy]

I used v 1.40 of EIGHTY one with the 66x2c ROM and whilst it works the CONFIG "X" command caused a crash. I haven't tried the other ROM in a later version of Eighty One as I'm only interested in real kit but would assume that the72x2c would work the same way with a later copy of the emulator.

[kmurta]

Fred and Paul, you are right, there is a problem with the zxpand+v72x2 ROM boot. And CAT also crashes the system when it fills the screen (seen the video below). Until I have a definitive solution, hold the SHIFT key during boot to force the MENU.P (ZXpand Commander) to load and use it to navigate and view the contents of the diretories.

Click to open

[kmurta]

Issues identified with zxpand+v72x2c ROM have been fixed, faulty file replaced in viewtopic.php?p=56168#p56168.

The basic functions have been tested and work satisfactorily, but I have not tested the ZXPAND command, if anyone who uses it can test and report, I will be grateful.

[Moggy]

Tried the ZXPAND command as follows..

ZXPAND "DELETE TF79.P" and it worked just fine (I did restore TF79 later!)

[Moggy]

In an earlier post I said that when using my logistic equation program, that the Big Bang ROM was throwing up incorrect results.
After much online calculator checking plus various maths web sites it now appears that it is the Sinclair ROM maths routines that are erroneous in this regard and in fact the Big Bang ROM is, to coin a phrase "bang on" in its workings out so not only faster but more accurate too.

Output example from Big Bang ROM (0.5) (1) then 0-0-0-0-0 ad-infinitum. (correct answer)

Output from Sinclair ROM (1) (1.8626452e-9) (7.4505806e-9) followed by a series of fluctuating decimals most >1 which is wrong as all output should never exceed 1.

I have deleted the relevant part of my earlier post.

[nollkolltroll]

I have added the zxpand+v72x2 rom as a selectable rom for OpenSpand. Very nice speed-up of scrolling when doing CAT!

[Skeet]

Since the use of this requires a new EPROM anyway, burning a dual rom with a switch is a really good way to go. Speed from the new rom for most things, and a fallback to original rom if/whenever things mess up. Just fantastic!

I was thinking about this.... I'm new to burning EPROMs and modding ZX81s so please forgive me if this is obvious. Which EPROM did you use and what modifications are required to use the dual ROM with switch?