ZX80 Space Invaders

Digital Prawn

I wonder if anyone managed to get this ZX80 game on the following page working?

http://home.micros.users.btopenworld.com/zx80/zx80software.html

Last week, I typed it into to the EightyOne Emulator (16K ZX80, standard ZX80 ROM, no extra hardware), but I just get error 7, which I think is RETURN without GOSUB

I saved the type-in as an EightyOne snapshot file here

http://java.cms.livjm.ac.uk/homepage/staff/cmspcar1/sinclair/

(Right-click on "spaceinv.z81" and "Save as" to download it).

It surely must be a mistake in my type-in, but I've checked it three times, and now my eyes have gone funny. Be interested to know if anyone else out there ever saw this working on an emulator? I'm probably blind to my mistake now!

Cheers, DP

NickH

I've definitely got it working before (Space Invaders was the only findable ZX80 game for a long time).

Buggered if I can remember the name of the emulator I used. I think it was called "NOCASH", or something like that. Space Invaders was packaged with it.

Digital Prawn

Thanks for the reply, I'll do some further research into ZX80 emulation... I've only used EightyOne so far. Still this problem is probably caused by a typo on my part somewhere.

In my case, looks like the Z80 machine code is actually returning control back to the USR statement, which I'm pretty sure shouldn't be happening. That would explain the program running away into the subroutine, and causing error 7.

I think the type-in would really benefit from a built in checksum!

Digital Prawn

aowen wrote: »

It should work with EightyOne.

Thanks! That's really good to read. Now I'm going to sit down and go through that listing again, in the knowledge that this should work on that emulator. (provided I can produce a perfectly correct type-in of course :) )

NickH

It might be one of these:

http://members.aol.com/streetern/Invaders.html

NickH

This is the emulator I remember using:

http://www.work.de/nocash/zx8.htm

Digital Prawn

NickH wrote: »

It might be one of these:

http://members.aol.com/streetern/Invaders.html

Brilliant! The file "Invaders.O" in that game pack is the same program as the one I have typed in.

Prior to downloading that, I just checked my type-in again, and can't for the life of me find out where I went wrong.

It doesn't matter now though, as the file you put me onto plays fine with the same ZX80 hardware configuration on EightyOne.

It's good to see all those other games that I never even knew about.

It's funny now that I spent so much time typing that listing in and checking it, as I was blissfully unaware of the above page, but I guess the typing in is all part of the fun and nostalgia etc!

Anyway, thanks again for all of your help, Cheers DP

NickH

Discovering the ZX80 scene requires a bit of Googling, but there's a lot more there now compared to five years(!) ago when I started researching the documentary.

Digital Prawn

That Space invaders game is pretty impressive when you consider the technical feat of having to simulate a ZX81-style SLOW mode on a machine that doesn't natively support it. (According to the website, it keeps calling the built in display routine at regular intervals)

But, it does play quite smooth considering, and is actually quite a mini-challenge, because the invaders kept shooting my "bullet" down.

I eventually finished off the entire wave, but alas after doing that, no second wave followed, and I was just left moving the gun around with nothing to shoot. So I guess by any practical definintion, I've now "completed" that one. There's always the greater challenge of clearing the wave without losing any lives though I suppose. It's a nice little game.