• Commodore Free - Issue 55 - Part 6

    From Stephen Walsh@39:901/281 to all on Mon Nov 7 14:38:54 2011
    to the beginning)



    The game loads and displays a screen with credits



    With a joystick in port 2 pressing fire loads to see our hero in a dungeon of

    some sorts



    Moving backward gains us a sword; bit of a tip as our guy is pointing forward

    you would assume you need to go this way, to collect the sword press down.

    The torches on the walls flicker to give the illusion of some sort of realism

    however they do not affect the lighting in the game in anyway. Our guy can

    move behind some scenery. It looks like it's a nice game



    HOWEVER

    Movement is slow and very flickery, pressing fire causes our guy to jump but

    with very heavy gravity I presume this is to point to the fact he is in a suit

    of armour and so his weight is affected. The screen flick scrolls whichever

    direction you move in left/right and then things get difficult



    Gaps in the floor of the dungeon will need to be jumped, as you weigh some

    considerable tonnage you soon find jumping is an art form in itself, you edge

    up to the hole as much as possible and launch yourself with the aid of the

    fire button hoping to clear the hole.



    Now the two small holes themselves don't pose to much of a problem and you

    continue deeper in the the dungeon looking around for more swords. The timer

    ticks on and suddenly! You reach a hole to big to actually jump, although

    there is a sword on the other side! This is where the games skill comes in,

    collecting swords opens doors and going through theses doors is the key to

    completing the game, as you will be moved to other areas and hence bypass

    large holes in the ground.



    At the end of the game the massages flashes on screen

    "Congratulations!"

    And a large pile of gold sits waiting for you to collect, and of curse Gold is

    the Kings best friend.



    GRAPHICS 4/10

    SOUNDS

    GAMEPLAY 4/10

    LONGEVITY 4/10



    OVERALL 4/10



    Its frustrating to play, mainly because it's so very slow to move around.



    ***************************************

    COMMODORE FREE INTERVIEW WITH

    Tokra CREATOR OF VDC-IHFLI

    ***************************************



    Q. Please introduce yourself to our readers.



    Hi, I'm Torsten Kracke aka tokra from Germany. About 18 months ago, my

    interest in Commodore machines was rekindled and I've since been active in the

    usual forums. Together with lots of help from Mike (from the VIC-20 Denial

    forum) I've released a VIC-20 demo called "Yes VIC can" at the Revision Easter

    Party this year.



    Q. Can you give some of your computing history and how you came across

    Commodore machines?



    About Christmas '78 or '79 our family got the first Pong-videogame, which in

    the later years I upgraded to an Intellivision, and then to a VIC-20 and

    finally a Commodore 128 before succumbing to the PC. I did a little

    programming on the Commodores; but just in BASIC, later took my first steps in

    Assembler and even released a C128-VDC disk to the Public Domain back in 1993

    - which you can still find around the net, or on my page now

    http://www.tokra.de/c128/64kvdcdisk.d64



    Q. Can you explain how you came up with the VDC-IHFLI display format?



    I was always interested in maxing out the graphic abilities of my Commodore

    machines as you can see by the VIC-20 demo! There was a commercial piece of

    software available for the C128 called "Graphic Booster" from a German company

    way back then. Graphic booster promised resolutions of 720x700 and 65000

    colours from the machine, However this was always way too expensive for me.

    Grabbing all the information I had from magazines and books, I finally managed

    to program my own BASIC-extension for the 720x700 resolution; and a few month

    later; I wrote a program for GEOS128 which can display a full GeoPaint-file in

    a resolution of 640x720. This was as far as I could get back then! Fast

    forward to 2010 when I found the amazing "Risen from Oblivion" demo for the

    VDC ; and discussions on the newsgroup comp.sys.cbm about high resolution

    graphic-modes on the VDC in colour.



    Q. What are the technical details for example the Screen resolution?



    The resolution used in VDC-IHFLI is 640x480 - colour resolution is 2 colours

    per 8x2 block and the vertical frequency is close to 60 Hz. 640x480 is a

    standard VGA-resolution which in itself is close to NTSC. I'm not too sure of

    the technical background here, but you will notice 640x480 in 60Hz is a pretty

    common resolution. Also, the maximum colour resolution the VDC will display

    without any tricks is 2 colours per 8x2 block. In 640x480 the bitmap uses

    38400 bytes and the colour information uses 19200 bytes, for a total of 57600

    bytes which still fits within the 64K of VDC-memory. This also shows why you

    need an expanded VDC-memory. Older C128-models only have 16K VDC-memory. You

    can see now that high resolutions cannot be achieved with that amount of

    memory. Luckily VDC-memory-upgrade kits are still available on eBay - just

    pull out the VDC from the socket, plug in the RAM-board, and re-seat the VDC.

    No soldering required.



    Commodore Free Editor notes on VDC upgrades

    At the time of writing you could obtain a VDc Upgrade from here

    http://www.ebay.co.uk/itm/Commodore-128-64K-VDC-Video-Memory-Upgrade-/

    310351185828?pt=UK_PC_Video_Games_Video_Games_JS&hash=item48425f47a4



    You will need of course to open your machine and plug the device in, full

    instructions are given the whole thing takes about 15 minutes to fit, I have

    purchased 2 of these myself from the seller. The units are new and I presume

    currently manufactured.





    Q. And in laymans terms then how is the image displayed on screen?



    The VDC-chip produces the full picture. The VDC Is a very flexible chip, if

    you know how to set its 37 (or 38) registers. Basically you just need to set

    the registers so that the VDC will display interlace-mode and the resolution

    you want it to display. Then it depends on the capabilities of your display

    device if you can see the results. Sadly, the VDC-chip hasn't been that well

    documented, but the C128 Programmer's Reference Guide is a great first help,

    as well as examining other peoples programs. Also very helpful was Richard42

    of the commodore128.org-forum who with an oscilloscope was able to provide me

    with frequency measurements.





    Q. So you still have to interlace or swap two screen very quickly to give the

    effect of a higher resolution, how then is the colour pallet created, and as

    you say the 64k VDC is need to hold both images in memory at once is this the

    case?



    Contrary to the C64's VIC-chip where interlace is done by software the

    interlace-effect on the C128's VDC is a hardware-capability of chip itself!

    The colour palettes are just the usual 16 CGA colours the C128 has in this

    mode. The illusion of more colours just comes through the interlace effect and

    because the pixels are so close together. That is also how the aforementioned

    Graphic Booster produces its "65000" colours - in reality its still just 16

    colours, just the eyes are fooled by patterns of different colour pixels.





    Q. Can you tell our readers how the demo images were they created, you took a


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