Oberon #03: Hardware: Solving Profi's Graphic Flickering

(C) POLTERGEIST'97

Poor and unfortunate users of Profi! For about six years now, they have been suffering from the fact that in games and demos, sprites and scrolling text jerk awkwardly, flicker, or even disappear altogether. Many of them know that the problem lies in the INT, and many have probably tried to do something about it, but nothing came of it, because the architecture of Profi is very special.

The creators of this computer acted very cleverly and wisely: instead of putting a lot of logic into selecting the necessary signals like KSI, SSI, PAPER, BLANK, etc., they installed just one RF2, recorded the timing diagrams of the signals in it, and fed a cyclic address sweep to the address lines of the RF, with the frame and line synchronization pulses already mixed into a single synchronization signal directly in the chip.

At first glance, the situation seems hopeless (and on the second as well) - the only thing that could be done was to "reflash" the RF2 (the INT also goes through this chip), but of course, the number of programmers per capita is insignificantly small, and you would all continue to suffer until the end of days if POLTERGEIST, that is, I, had not taken on this problem!

About six months ago, someone brought me a Profi and demanded that I redo its INT from a more left one, which looks nothing like anything, to a less right one, which at least resembles something. "What the heck?" I thought back then, - "if I fix the INT in Profi, then you can even watch MULTICOLOR on it, since its raster matches that of PENTAGON, and the memory is transparent," and I took on this problem seriously. After some time, I came to the conclusion that "small blood" wouldn't work here and the simplest solution was to reflash the RF. So, I desoldered the chip, counted, moved the INT to a more correct place, and was already ready to take it for "flashing," when a devil made me peek into the bit of the RF, which was marked as unused in the schematic.

And what do you think I discovered there??!

Nothing other than a clean frame synchronization pulse. Thus, the axiom stating that everything genius is simple was confirmed once again.

So, here’s what you need to do to make the INT more correct and even get MULTICOLOR to work:

1) Turn down your system

2) ... Oh! I forgot that you are not dumb IBM users, but more knowledgeable SPECTRUM users. In short, find on the lower board of your Profi a big cockroach with 24 legs. Find the 13th leg (the legs are counted counterclockwise starting from the key) and cut the trace going from it. Throw the cut trace onto the 14th leg, and after that your INT will be practically PENTAGON's. The KSI phase relative to SSI in Profi is somewhat different than in Pentagon, and because of this, the border stripes will be shifted to the side. At the time, I didn't solve this problem, and now it's too late since I don't have either a Profi or its schematics at hand. And the matter may not be more complicated than wiring.

In short, I think everything is clear even to those who don’t know which end to pick up the soldering iron.




Yes, by the way, if you want to re-connect the INT from PENTAGON's to the "branded" one, you can solder it all according to the schematics provided below.  The first option is simpler, but the second schematic is more interference-resistant. (The traces with arrows   on   the drawing should  be connected to the INT generator)          



And finally, I want to warn programmers who have Profi: do not synchronize MULTICOLOR with this newer INT - your creations will most likely glitch (slightly!) on the same PENTAGONS.

Now, allow me to bow and say goodbye:                                
it was POLTERGEIST          
 From Samara          
                                          
13.02.97
                                          
P.S. Don't forget to check the ads!     


O:> From the editorial office, we would like to say the following: as of today, there are practically no known Profi in Samara that have not been modified according to this scheme. Imagine - an entire city, and nowhere to see the glitches! As you may have understood, after this modification, not only does MULTICOLOR start working, but the sprites and scrolls in music demos stop jerking as well!   

The border indeed remains somewhat different than on PENTAGON, but that’s not so important. The main thing is that if effects occur in the upper or lower part of the border, they practically coincide! The most astonishing thing for all of us was that the unique and unparalleled set of MULTICOLOR effects, written by Samara programmers (part of GIFT FOR M.M.A (SPEED CO.'96)) works on the modified Profi just like on a live PENTAGON, for which it was actually synchronized for two weeks! And not to mention that MULTICOLORs work without problems in                     

 SATISFACTION, INSULT, ECSTASY, ENL'96 DEMOS,
   BRAIN CRASH and many, many others!  

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Contents of the publication: Oberon #03

• From the Authors
  The editorial of the third issue of Oberon reflects on its wide distribution across Russia and nearby countries, overcoming production challenges, and its aim to cater to various readers, including gamers, programmers, and hackers.
• How to Write in Oberon - M.M.A
  Guide on submitting articles to Oberon using ZX-WINWORD. Detailed format and process explanations for text, graphics, and music. Insight into editorial practices and preferences.
• Scroll - M.M.A
  A historical overview of the game THE EIDOLON on ZX Spectrum, covering its restoration process and gameplay mechanics, including level challenges and story background.
• Scroll
  Dark Star is a space shooter game where players pilot a ship against a tyrannical alien race. Players customize settings, navigate space, and combat enemy forces on various difficulty levels. Strategic planning and skill are vital for successful gameplay.
• Scroll - M.M.A
  Detailed gameplay mechanics for the game with Mechnotech klp2. Strategy involves disarming reactors and managing droid transformations. Insight into different droid types and weapons available.
• About Everything - M.M.A
  Discussion of reader interactions with the 'Oberon' editorial team, including feedback on previous issues and commentary on game compatibility and magazine content improvements.
• About Everything - M.M.A
  The autobiographical article explores the author's role in Samara's ZX Spectrum scene, detailing his contributions and aspirations. M.M.A positions himself as a leader and innovator in the community. It highlights the importance of local distribution and cultural impact.
• Amiga rulez? - M.M.A
  Critical essay on contemporary computer culture, contrasting IBM and Amiga platforms. Discusses societal impact of IBM standardization and advocates Amiga as a symbol of creativity and individuality. Reflects on the evolution of computer usage and preferences since the ZX Spectrum era.
• What Should 'Boot' Be - Unbeliever
  The article explores the evolution of boot programs for ZX Spectrum, discussing early developments and key innovations over time. It highlights significant breakthroughs in automation and design, including fully assembler-written boots and the introduction of modern features. The text concludes with reflections on ideal boot characteristics from a contemporary user's perspective.
• Letter from Queen Software
  An open letter from Queen Software criticizes ZX-WINWORD's design and Russian keyboard layout, denounces 'Mortal Compot' and the degradation of games, and shares views on demoscene events and computer emulation.
• Review - Unbeliever
  The review provides insights into various 128K exclusive games for the ZX Spectrum, highlighting titles like 'Space Gun', 'World Championship Soccer', and 'Night Breed'. Special attention is given to their graphical prowess and gameplay mechanics. Furthermore, the article addresses the acquisition of Spectrum software via the Internet.
• Review of Assemblers - Maxsoft
  Review of various assemblers for ZX Spectrum, highlighting their strengths and weaknesses. Focus on EDAS 3.3, AFS, XAS, ZX-ASM, ALASM, MASM, and TASM 4.1. Each assembler is evaluated on performance, features, and usability.
• Our Answer - M.M.A
  Critical analysis of the electronic journal FAULTLESS, highlighting plagiarism issues and content quality. Discussion on the comparison with OBERON and other journals. Suggestions for improving FAULTLESS are provided.
• Our Response - Alex Noman
  Debate over the compatibility and capabilities of Scorpion and Profi computers with the ZX Spectrum. Critique of programming claims by Chung Software regarding outdated languages and methods. Discussion on operating systems like CP/M and iS-DOS in the context of their utility in modern computing.
• Our Response
  Exploring the varied interpretations of the term 'hacker' in Russian, highlighting distinctions and misconceptions.
• Hardware - Dr.Death
  Connection instructions for AY-3-8910 on Spectrum-compatible machines. Solutions for common audio issues in Russian computers. Advice for improving digital sound compatibility.
• Hardware - Dr.Death
  Discussion on modifying SCORPION ZS 256 for better performance, focusing on timing issues and TURBO mode. Explanation of improvements and potential problems with multicolors. Suggestions for further upgrades.
• Hardware - Poltergeist Corp.
  Analysis of hardware issues with Profi, a ZX Spectrum clone, focusing on INT signal problems causing graphic flickering. A solution is proposed involving a simple hardware modification. The author shares their success and the widespread adoption in Samara.
• Let's Gurm
  A microdrama illustrating the chaotic interaction between computer components during a printing task.
• Let's Feast
  Satirical story depicting an alternate reality where American culture and symbols are humorously twisted by Soviet influences.
• Let's Feast
  The story humorously describes Popov's efforts to help Papuans progress, amid desert struggles, political intrigue, and personal challenges.
• Let's Discuss
  Overview of military jargon known as 'Army Absurdities' collected by students, highlighting unique language and instructions used in military training and communications.
• Let's Feast
  Satirical article describing military humor and fictional military equipment.
• Literacy Campaign - Paul Atrides
  Analysis of hacker misconceptions and societal attitudes, exploring hacker culture's roots and ethical dilemmas.
• Primer - Paul Atrides
  Article discusses the role and activities of Russian hackers in the late 1990s, highlighting notable cases and categorizing different types of hackers. It covers the operations, risks, and impacts of hacking on international and local levels. The text also examines the societal perception of hackers and their portrayal in media.
• Contest - M.M.A
  A contest involving identifying songs from poorly translated lyrics, inspired by a radio segment. Participants guess the song and artist. No specific prize yet, but a free journal issue is promised.
• Contest
  A poetic reflection on personal struggle, misunderstood communication, and the burden of saving the world.
• Contest
  A poetic reflection on isolation and inner dreams, contrasting with harsh reality.
• Contest
  The article presents a poetic tribute to the community, emphasizing themes of unity, immortality, and strength through metal music.
• Advertisement
  Advertisement in Oberon magazine offers free publication and discusses available software, hardware, and stores related to ZX Spectrum.
• Advertisement
  Advertisement of computer repair and upgrades with pricing for various services. Options include drive connection, signal normalization, and memory upgrades. Specific services for different computer models like Pentagon and ATM.