Thoughts on "Slippery Sid"

spider · August 2017

I did always quite like this, as for the game type I found it quite straightforward to play although I'd be interested to hear suggestions of alternatives, the more 'uncommon' the better. :)

It repeats after about L5 though or thereabouts, the same over and over again although I think the snake is longer each time. I've not bothered to play past about L7 and its got boring by then.

Question: Is Slippery Sid compiled Basic ? I noted a bit of text relating to Softek in the Basic once you dismantle it a bit but I could not immediately see anything else.

I did try to cheat my removing the pattern from the 'killer cell' UDG block but then they just became invisible (as expected!) but still deadly, so it made the game very difficult indeed. :D

Pgyuri · August 2017

After fast checking 99 % percent it was written in Basic and compiled to Z80.

It was an used procedure with many games and you can find many good (for ex. Gotcha). If you check the code, you can find it is very simple ...

In this game you can see same many times in the code:

ld hl,($6002)
ex de,hl
ld hl,$0002
and a
sbc hl,de

This is a simple LET X=X-2

Skill Z80 programmer doesn't write this code, instead use:

ld hl,($6002)
dec hl
dec hl

There is no text about the compiler, that's why I think it was something "own" or any early time simple compiler.

Here is a small part of my disBASICing from Gotcha what was written in basic and compiled by WYE VALLEY SOFTWARE COMPILER V 0.2

        LD      HL,(LIVES)
        PUSH    HL
        LD      HL,$0001
        PUSH    HL
        POP     HL
        POP     DE
        AND     A
        EX      DE,HL
        SBC     HL,DE
        LD      (LIVES),HL  ; LET LIVES=LIVES-1

or

        LD      HL,(GUARD)
        PUSH    HL
        LD      HL,$0000
        POP     DE
        LD      B,$3D
        CALL    _proc_IF
        JP      NC,LB32C  ; IF GUARD<>0 THEN GO TO
        LD      HL,$0001
        LD      (GUARD),HL  ; LET GUARD=1
        LD      HL,$001F
        LD      (GUARDPOSX),HL ; LET GUARDPOSX=31
        LD      HL,$0001
        CALL    _proc_MINUS
        LD      (GUARDPOSY),HL ; LET GUARDPOSY=-1
        LD      HL,$0001
        PUSH    HL
        CALL    _proc_RND
        PUSH    HL
        LD      HL,$1770
        POP     DE
        CALL    _proc_DIVISION
        PUSH    HL
        POP     HL
        PUSH    HL
        POP     HL
        POP     DE
        ADD     HL,DE
        LD      (GUARDRND),HL  ; LET GUARDRND=RND/6000+1
        LD      HL,(GUARDPOSY)
        PUSH    HL
        LD      HL,(GUARDRND)
        PUSH    HL
        LD      HL,$0003
        POP     DE
        CALL    _proc_MULTIPLE
        PUSH    HL
        POP     HL
        PUSH    HL
        POP     HL
        POP     DE
        ADD     HL,DE
        LD      (GUARDPOSY),HL ; LET GUARDPOSY=GUARDPOSY+3*GUARDRND

The hole program can be translated back to Basic :) Was I understable ?

Morkin · August 2017

I remember this game from the early days of the Speccy. Always liked the look of those Mirrorsoft ads/cassette covers in the magazines. I had no idea what the game was like due to lack of screenshots back then, and was quite disappointed when I finally got round to playing it. Same with Cyber Rats.

textvoyage · August 2017

Yeah I liked the game. ( @Morkin sorry to be pedantic but it was Silversoft not Mirrorsoft!)
I didn't even know that compiled BASIC was a "thing" back then (1983), so thanks for mentioning the Wye Valley compiler, very interesting.

Morkin · August 2017

Oops, yep, sorry, getting my 'softs' mixed up... :D

sirclive1 · August 2017

one of the 1st games i bought , along with 3d sieddab attack , hated it then , swapped it with a mate for maze death race .

Luny · August 2017

Amazing how the years blur, I would have sworn Slippery Sid was a 1982 game, its down for 1983.

spider · August 2017

Thanks all :D The partial code is quite nice to see too.

Thoughts on "Slippery Sid"

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