Rom hex file help

[darrencch]

Hello to all,I'm Darren from Australia and I have just finished PokeMon's awesome ZX80CORE and its up and running with the standard ZX80 rom I would like to try some other roms if anyone could point me in the right direction. I have had a bit of a look around the web in search of other rom images to burn but most appear to be games. I am a fan of Hex code and have a few Z80 based kits from my childhood mainly the Australian Talking electronics computer "TEC 1D" and a few others so I'm looking for similar machine code fun for the ZX80CORE and make use of the rom selector switch.

thank you in advance

Regards

Darren

[PokeMon]

Well you could download the great emulator EightyOne which provide a rom directory after installation with many officially published rom versions.
http://www.chuntey.com/

You maybe find different roms for ZX81 or ZX80 as well here (only german but not much text to read):
http://www.8bit-wiki.de/8bitdb.html?&no_cache=1

I am not sure if you have the ZX80NMIX, the NMI board. This is needed for most ROM versions. Even the ZX81 supports the SLOW mode only with NMIs.

[Moggy]

Whilst Eighty One contains a lot of ROM images I have come across at least one that I suspect has been "tweaked" from the original to work with the the emulator.
One such ROM is the h4th ROM which gives a correct display in Eighty One but when burned to an EPROM and used on real equipment produces a display that is too far up vertically and to the right of the screen, also when the routine that turns the screen inverse is called, the inverse "mask" is one column too far to the left leaving the far right hand column non inverted, but again works ok in Eighty One.

As nobody seems to posses an original Husband forth ROM we will never know the difference.

I seem to recall also that Eighty Ones creator had to tweak the Jupiter Ace ROM to get it to work correctly with Eighty One.

[PokeMon]

This is an interesting information.
I tried to get the H4TH rom with the ZX80CORE together (with NMI module) - but did not work.
I ever wanted to check the reason but when it is tweaked I maybe don't have to wonder why it is running in EightyOne with no problem.

[darrencch]

Thanks for the information, I don't have the NMI board but the mad scientists in me is considering running a z84c0020 with two crystals one 20mhz and the other 6.5mhz and some logic to switch between the two or maybe a single 13mhz divided, 13mhz gives a screen image of 4 smaller images displayed.

[oscar]

... Z80 based kits from my childhood mainly the Australian Talking electronics computer "TEC 1D"

Wow, that brings back some memories; like you, I grew up reading that magazine. I can't help you with your ZX80CORE quest, but I wish you luck. My current "project" is programming an Altair clone, but I'm finding it hard to get the hang of coding 8080 after years of being spoilt by the power of the Z80

[stefano]

Interesting indeed !

I also noticed that with EightyOne, even if possible, is not easy to understand that you can run zx81 ROM on a ZX80: It was an official retrofit, even if it couldn't go in SLOW mode.
I suspect that the G007 was able to run on a retrofitted zx80 since it patches both the FAST and the SLOW parts of the rom.

[PokeMon]

It was an official retrofit, even if it couldn't go in SLOW mode.
I suspect that the G007 was able to run on a retrofitted zx80 since it patches both the FAST and the SLOW parts of the rom.

Well the SLOW mode integration was designed perfectly to be compatible to the FAST mode (the only one ZX80 hardware do support).
The difference in the video routine is quite easy. There is just a switch to detect if FAST or SLOW and during FAST mode the margin lines are executed as empty video lines with a simply HALT instruction including hsync generation by software while the SLOW mode does switch on a hardware NMI generator to create the sync pulses and let the program execute in the meanwhile (in the background).

The more I am working with the video hardware the more I detect it's beauty. The design is really ingenious.

[stefano]

Yes, also the europe/america diode trick is great !

About the ROMs.. I don't think they're tweaked, my impression is that h4th was for a 60hz raster only while aszmic was for 50hz only.
At least it's the way EightyOne behaves.

[Moggy]

Yes, also the europe/america diode trick is great !

About the ROMs.. I don't think they're tweaked, my impression is that h4th was for a 60hz raster only while aszmic was for 50hz only.
At least it's the way EightyOne behaves.

@stefano
H4th was the original forth rom created by David Husband's Skywave software co and is a 50htz ROM whereas the Tree4th ROM used in eighty one is the 60htz rip off.

When I say tweaked what I mean is that the h4th ROM was altered somehow to work in eighty one, as when the ROM image from eighty one is used on real equipment it exhibits the display faults mentioned in my earlier post.
As I also said earlier I seem to recall also that Eighty Ones creator had to tweak the Jupiter Ace ROM in the same manner to get it to work correctly with Eighty One.