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Skull Cave on the Sol-20

Posted: Fri Feb 12, 2016 2:41 pm
by impomatic
Here are a few screenshots of Skull Cave, an adventure by Ray White for the Sol-20 which I've been playing on and off using an emulator. It's not listed in the archive yet.

Title: Skull Cave
Authors: Ray White
Platforms: Sol-20

Available from http://www.sol20.org/programs.html
SKULL.png
SKULL.png (920 Bytes) Viewed 4281 times
SKULL2.png
SKULL2.png (4.18 KiB) Viewed 4281 times
SKULL3.png
SKULL3.png (4.15 KiB) Viewed 4281 times

Re: Skull Cave on the Sol-20

Posted: Thu Feb 18, 2016 2:16 pm
by Gunness
Thanks! I don't think we have anything on the Sol 20 at all? Or maybe I can't find my way around the database. It's a DIY-kit, right?
I took a brief look at the link - are there other games for this machine than Skull Cave?

Re: Skull Cave on the Sol-20

Posted: Fri Feb 19, 2016 12:30 pm
by impomatic
Gunness wrote:Thanks! I don't think we have anything on the Sol 20 at all? Or maybe I can't find my way around the database. It's a DIY-kit, right?
I took a brief look at the link - are there other games for this machine than Skull Cave?
The Sol-20 was available as a kit (or fully assembled) in the late 70s. Skull Cave is the only adventure I've found.

I tried to contact the author to confirm the year Skull Cave was written / published but had no luck :(

Re: Skull Cave on the Sol-20

Posted: Fri Feb 19, 2016 8:15 pm
by jgerrie
Is there source code for the game? What was it written in?

Jim G

Re: Skull Cave on the Sol-20

Posted: Tue Feb 23, 2016 2:42 pm
by Gunness
I've added the game to the database :)

Re: Skull Cave on the Sol-20

Posted: Wed Feb 24, 2016 10:48 pm
by impomatic
jgerrie wrote:Is there source code for the game? What was it written in?
Sorry, I haven't seen the source so I'm not sure of the language. If I ever manage to track down the author I'll ask.

Re: Skull Cave on the Sol-20

Posted: Wed Mar 23, 2016 1:03 am
by dave
After a quick conversation of the .ent format to raw binary, it's definitely not BASIC, so I'm guessing it's pure Z80 machine code.

I used a very basic Z80 disassembler to have a look through and it does seem to make sense. So raw Z80 would be my guess.

Re: Skull Cave on the Sol-20

Posted: Wed Mar 23, 2016 6:32 pm
by jgerrie
Thanks Dave. Any chance you can dump the assembly to a text listing. I might be able to pluck the locations descriptions and messages and then use a generic BASIC game engine and a walkthrough to create a work-a-like of the game in BASIC. I did that with Forbidden Planet... No worries if it too much trouble.

Re: Skull Cave on the Sol-20

Posted: Wed Mar 23, 2016 8:56 pm
by dave
Here's a zip of the raw binary - we can see all the text and command words in the clear.

I'll boot up my laptop with IDA pro on it tonight and see what I can get from a disassemble of it.

Re: Skull Cave on the Sol-20

Posted: Sat Mar 26, 2016 2:56 am
by jgerrie
Thanks Dave. It looks promising.

Re: Skull Cave on the Sol-20

Posted: Sat Mar 26, 2016 11:54 am
by dave
I had a quick look through it - I was wrong on the processor: it's an Intel 8080, which is very similar to the Z80 (it's what the Z80 was cloned off).

But, my lack of familiarity with the processor doesn't help, so I didn't get too far in working out the logic, sorry.

Some easy ones though:

Introduction text starts at 0x55b. There are some low bytes in there which I'm guessing are formatting.

Words start at 0x799 and separated by full stop (0x2e) characters, there appears to be no distinction between verbs and nouns.

The difficulty levels start at 0xa22, with a format of:

Code: Select all

ushort number
char name[]
Where the number is a big endian number, which seems to be in multiples of 100.

Objects start at 0xbc0.

Rooms start at 0xfa8.