Sinclair ZX80 / ZX81 / Z88 Forums

There are several versions of games based on Star Trek for zeddy, all very similar to each other. Such similarities have always made me suspicious of a common origin, which was totally unknown to me until a few days ago when I came across this topic: viewtopic.php?f=4&t=670 (yeh, it took me 9 years to get here )

Following the links, I discovered that one of the first versions was developed by Mike Mayfield in 1972 for the HP2000C computer. Subsequently, it was published by David H. Ahl in the book "BASIC Computer Games", receiving several additions. After finding a text listing of the game, I decided to take the challenge for myself and convert it in full to the ZX81.

The result I present here, fully functional and interactive! The disadvantage is that because it is in BASIC, the processing is too slow and I had to use FAST mode to speed up the heavier processing (for Zeddys equipped with Andy's ZXULA2, it's recommended to activate the Turbo mode before loading the game. All FAST instructions in the game are already followed by the respective "POKE 1001, x").


The game requires at least 32Kb of RAM, which will not be a problem for ZXpand owners. There are two programs: the first contains the game instructions and is also responsible for setup the RAMTOP to value 49152 before load the second program, the game itself.

I hope you like it, I particularly found the game really fun!

I have always had a liking for this game so many thanks for this kelly.

You may or not know that a double speed BASIC ROM is available now for the 81 and I will try this with that ROM to see if it speeds things up.

The thread about the ROM can be found here...

https://www.sinclairzxworld.com/viewtop ... f=5&t=2986

Moggy wrote: ↑Sun Feb 16, 2020 1:18 pmYou may or not know that a double warp speed BASIC ROM is available now for the 81 and I will try this with that ROM to see if it speeds things up.

The thread about the ROM can be found here...

https://www.sinclairzxworld.com/viewtop ... f=5&t=2986

Corrected that for you....!

Mark

1024MAK wrote: ↑Sun Feb 16, 2020 4:07 pm

Moggy wrote: ↑Sun Feb 16, 2020 1:18 pmYou may or not know that a double warp speed BASIC ROM is available now for the 81 and I will try this with that ROM to see if it speeds things up.

The thread about the ROM can be found here...

https://www.sinclairzxworld.com/viewtop ... f=5&t=2986

Corrected that for you....!

Mark

Nice one Mark.

Moggy wrote: ↑Sun Feb 16, 2020 1:18 pm I have always had a liking for this game so many thanks for this kelly.

You're welcome!

Moggy wrote: ↑Sun Feb 16, 2020 1:18 pm You may or not know that a double speed BASIC ROM is available now for the 81 and I will try this with that ROM to see if it speeds things up.

Yes, I know it and I even tested the game with this improved ROM in the EO emulator. My intention was to leave all prints running in SLOW mode, but seeing the Scan Sensors and Galaxy Maps being printed slowly on the screen is too tedious. But with the ZX81X2.ROM, both processing and printing speeds are significantly increased!

By the way, has anyone hacked it for use on ZXpand?

I think professor Andy was thinking about it!

https://www.sinclairzxworld.com/viewtop ... f=5&t=2986

Post 5.

Thanks Kmurta…
Nice game.

A point to note for ZXpand users.

Don't rely on the program setting RAM-TOP to 49152!

Before loading you must use the CONFIG"R=49152" command before loading otherwise a nasty little whiteout happens.

I tried this on four different spands ( issue 1,3 and 5 and the xpand+ ) and they all crashed unless RAM-TOP was set first by using the CONFIG command and not relying on the program setting it as Kelly suggests.

Moggy wrote: ↑Sun Feb 16, 2020 7:00 pm A point to note for ZXpand users.

Don't rely on the program setting RAM-TOP to 49152!

Before loading you must use the CONFIG"R=49152" command before loading otherwise a nasty little whiteout happens.

I tried this on four different spands ( issue 1,3 and 5 and the xpand+ ) and they all crashed unless RAM-TOP was set first by using the CONFIG command and not relying on the program setting it as Kelly suggests.

Hmmm, what happens is that to work it must have RAM up to 49152. The problem is that ZXpand start with RAM set to 8-40Kb. As I use Commander by default and it automatically sets the memory to 16-48Kb, I forgot that detail, sorry.

But as really there isn't need to always load the instructions before the game, it may be better to use CONFIG "R=49152".

kmurta wrote: ↑Sun Feb 16, 2020 8:21 pm

Moggy wrote: ↑Sun Feb 16, 2020 7:00 pm A point to note for ZXpand users.

Don't rely on the program setting RAM-TOP to 49152!

Before loading you must use the CONFIG"R=49152" command before loading otherwise a nasty little whiteout happens.

I tried this on four different spands ( issue 1,3 and 5 and the xpand+ ) and they all crashed unless RAM-TOP was set first by using the CONFIG command and not relying on the program setting it as Kelly suggests.

Hmmm, what happens is that to work it must have RAM up to 49152. The problem is that ZXpand start with RAM set to 8-40Kb. As I use Commander by default and it automatically sets the memory to 16-48Kb, I forgot that detail, sorry.

But as really there isn't need to always load the instructions before the game, it may be better to use CONFIG "R=49152".

@Kelly.

I also use commander and no matter if mem is high or low it won't run on a real 81 from a normal load command unless CONFIG "R=49152" is used first.
I 'm only pointing this out for your own reference Kelly nothing more.

The game itself is superb but a damn sight harder than other versions but I am the worlds worst game player only three Klingons destroyed then they got me.

Great work Kelly and thanks again for this.