Jump to content
Have You Played Atari Today?
2600|5200|7800|Lynx|Jaguar|Forums|Store  

tf_hh

+AtariAge Subscriber
 View Profile  See their activity

  • Content Count

    1,041

  • Joined

  • Last visited

Posts posted by tf_hh

  2. Posted

    Stock 800XL works intermittently. Locks up after use. Reset with black screen, or blue screen with static cursor, or a line like this traveling up the screen in flickers (see attached image). Also note deformation at top of screen. Any ideas on which components might need assessment?

     

    As Nezgar already wrote, I strongly recommend to check the RAMs first. In your screenshot you can see a part of the display list (the three little P´s is the start of every standard display lists in the O.S.). This behavior is typical for the often bad Micron (MT) DRAMs when one of the muxed addresslines is defect.

    • Like 2

  3. Posted

    Hi,

     

    today I found an absolute new and strange behavior reparing an Atari XEGS. I never have had such an error before neither I found something similar here. So maybe this could help other people with the same strange issue.

     

    The XEGS I got comes with the fault description "System hangs if Missile Command is started or sometimes the game just resets" (reset = start from the beginning, same if you would press START at any time). I can reproduce this error easily.

     

    So first, I watched the SYNC signal at the CPU - but even when the game hang, there´s activity on SYNC. So I decide first to change the ROM - I have a lot of ROM failures specially by the XEGS. After ROM the MMU was changed. But the fault remains. Ok, next step would be the CPU. CPU failures are from my experience the 2nd most related things after RAM memories. CPU exchanged, but you can imagine... that also didn´t help.

     

    BTW: Before I change any part, of course I watched every single pin of the CPU, GTIA, ANTIC and the FREDDIE. All fine.

     

    I connect a keyboard, start BASIC, enter some simple calculation endless loops with PRINT´ing them, this works for hours. I attached an SIO2SD, load Missile Command (file version) and... it works. No problems at all.

     

    Ok, which components might cause the CPU to make a break... ANTIC? GTIA? All signals (RDY, HALT, IRQ) looks good. After all, I didn´t found other ideas, so I decide to remove all chips, solder sockets in and put well-known working parts into the XEGS mainboard.

     

    Start the next test, no keyboard, Missile Command starts and... hang. Now - wished I had test this first, a lot of spent hours would have been saved - I connect the keyboard, start the XEGS with SELECT hold down and Missile Command starts. I didn´t know this before, that Missile Command could be started also with keyboard instead of Atari Basic. I don´t have an XEGS for my own, so I haven´t play around much with this.

     

    WITH keyboard attached the Missile Command works fine. No problems.

     

    Now I examines the POKEY more then before. Without keyboard I see on the scope, the IRQ line is sometimes low for over 10 times of a PHI2 phase! At every time IRQ goes low for such a long time, the game hangs, resets or makes other weird things. With keyboard attached this never happens, IRQ remains constantly high while the game is running - what I expect, then Missile Command didn´t read the keyboard nor SIO etc., it uses just the joystick ports and console keys, which are attached to the GTIA.

     

    After some more examining the POKEY I saw, that pin 16 and pin 25 of the POKEY - KRx lines - are heavy floating from -0.5 volts up to 2 volts. Now it would be clear: POKEY "thinks", a key a pressed, generate an IRQ, but the OS (which is active during the game, ATTRACT will also work) can´t read the source. In case of the bad floating signal the POKEY will generate a long IRQ, longer than normal, which cause the CPU to halt - like some of the "CPU breaker" with R/C links from the 80s.

     

    But... the XEGS is MADE for usage without the keyboard... so why this happens?

     

    Checking with another XEGS boards, the culprit was found very fast: It was the parsimony of Tramiel´s area, removing some necessary parts to save some cents. The "good working" XEGS has line filters in the KRx (and other) lines, which will prevent these open inputs from floating around and beeing using like an antenna. At this special board, Atari replaces these line noise filters by simple 0R resistors. See this board:

     

    post-15670-0-11065900-1541260764_thumb.jpg

     

    The fix is absolute simple, after all I´m so silly not to find this earlier, but... now it works. And maybe it helps others from spending so much time to repair an XEGS ;-)

     

    Just solder two 1nF capacitors between ground and the both KRx lines - that´s all. Of course you can use wired capacitors, too. Now there´s no floating inputs and the system works fine - with or without keyboard...

     

    post-15670-0-66089600-1541260770_thumb.jpg

    Jurgen

    • Like 13
    • Thanks 1

  4. Posted

    Shipping from Europe is not much more than from US.

     

    Hmm, IMHO this is not correct. For example, I can sent up to 500 grams of weight in a box sized 25 cm x 20 xm x 5 cm (length x wide x height) for <7 Euros incl. tracking number and insurance up to approx. 35 Euros (the exact value varies, it´s called "SZR" and a synthetical currency of the international post services). That´s enough for a lof of PCBs and parts, and you can use real boxes, not just aircushioned envelopes. Higher insurance is possible up to 1000 Euros with extra costs.

     

    On the other hand, already the smallest envelope with 50 grams will costs 11 US-Dollar from U.S. to Europe. Without any tracking number, without insurance. Today the US-Dollar and Euro are near by 1:1, so it´s more safer and cheaper to sent goods from Europe to U.S. than the other way :)

  7. Posted

    several years ago every Abbuc member could vote for the Hardware contest (just like it is the case with the Software contest). But there was hardware (no matter if "final" or "in development") where a simple non-techie Atarian could not judge if it is any good, as good or better as another hardware item, etc., so the Abbuc members decided it would be better to have a jury that has enough knowledge about hardware in general. Think the guys that were originally in the jury (TG one of the guys that built the SIO2USB and other hardware; JVR the hardware doctor that repairs A8 hardware and builds lots of new hardware; EP the Abbuc Floppydoc that repairs Atari floppy drives and even tape drives; do not remember the other ones atm) did have enough knowledge to be qualified for this job...

     

    Alas, after several years and some heated discussions at the JHV it turns out, that the jury seems not to be fully neutral, they sometimes seem not to judge about the hardware, but about the Atarian that made the hardware (and if they like him or not). Thats also the reason why one of the hardware jury members left the jury. Of course we have the same problem in the software contest, but to me it seems more obvious in the hardware contest...

     

    Because you state my name (JVR = Jurgen van Radecke, that´s me) in the first part of your text (what´s absolute fine for me!) I want to make sure that everybody knows that I´m also the one who left the jury after one year.

     

    The reasons are mainly already spoken out: Personally dislikes against participants of the contest from some members of the jury and missing neutrality. Some other harsh things happened in email correspondence, which I wouldn´t release to the public.

    • Like 1

  8. Posted

    The screws aren't sharp and don't touch the mylar.

     

    Maybe I´m silly, but until today I have no suggestion how these screws and the single-layer mylar will work. The both pictures in the other thread don´t show really how they are assembled. Could you show any real example, please?

    • Like 1

  9. Posted

    I have started production of 800 and XE single-layer mylars, next will be 1200XL and maybe 800XL. If there is still enough demand, I can make XE double-layer and 400. However, Simius produced a lot of them for XE.

     

    I would buy:

     

    minimum 5 pieces 1200XL keyboard

    minimum 5 pieces 800XL "stackpole" mylar keyboard

    minimum 5 pieces XE doubly-layer mylar keyboard

     

    Jurgen

  12. Posted

    Let make an simplest of all. Why not, some of you already made an prefect disk image with fixed 3 sectors and drop the disk images here ready ? Why not ?

     

    This is impossible, because all known sector copiers only accept 128 bytes for the three first sectors of each disc. This is the reason why the CP/M boot sectors are destroyed.

  15. Posted

    Hi,

     

    I´m a bit surprised, because I thought the manual in junction with Trub´s website did explain everything. So I will try to summarize all needed steps here again:

     

    1. Take any sector copier you want and copy the following files to one physical real disk using your Indus GT drive each:

     

    Indus RAM Charger Check.atr

    Indus RAM Charger 40-80 Terminal.atr

    Indus RAM Charger CPM Boot.atr

    Indus RAM Charger CPM BIOS.atr

     

    2. Boot the disc with no BASIC (OPTION held) from your Indus GT drive containing the file "Indus RAM Charger Check". Press "L" and RETURN, enter "CPMTOOL.COM" and RETURN.

    3. Press "1" to test your SRAM charger. First the installed ROM version will be displayed. If your version is below 1.20, then CP/M is not possible! See below.

    4. Test your SRAM charger :)

    5. Insert the disc containing "Indus RAM Charger CPM Boot" and press "2" (Fix CP/M boot). Confirm with "Y". A few sectors will be written.

    6. Insert the disc containing "Indus RAM Charger CPM BIOS" and press "2" (Fix CP/M boot). Confirm with "Y". A few sectors will be written.

    7. Switch off computer, insert the disc "Indus RAM Charger 40-80 Terminal" and power on with OPTION held.

    8. DOS XL will be booted and some hints how to continue. Press "F" for the 40 column terminal or "E" for the 80 column version, then RETURN

    9. After the terminal software is loaded, only a light green cursor in the upper left corner will be visible. That´s normal.

    10. Insert the disc containing "Indus RAM Charger CPM Boot" in your Indus GT drive.

    11. Press "DRIVE TYPE" on your drive, hold it down and press the ERROR key.

    12. A beep will be hearable, drive boots now CP/M. The message "FUTURE CPM 2.2 REV 1.0 - Hit RETURN to continue" appears,

    13. Hit RETURN and a prompt "A>" with a Digital Reseach copyright notice will be displayed.

     

    That´s all. Now you can load CP/M programs and use the commands found in the disc(s). A directory is shown by enter "DIR" <RETURN>

     

    Important notice on firmware!

     

    Some Indus GT drives may have a firmware version below 1.20 - then CP/M can´t be loaded! You´ve to upgrade the Indus GT firmware before.

     

    Find the V1.20 firmware here: indus_1.2.rom

     

    The firmware can be burned into a standard 2732 EPROM (4 KByte). You didn´t need to change anything on the PCB, just remove the old ROM or EPROM at socket U3 and plug in the new burned 2732 EPROM.

     

    There´s an alternative version - V1.2 enhanced: indus_1.2.enhanced.bin

     

    This is a patched V1.2 with enables Highspeed-SIO with "standard" Highspeed-SIO routines like Hias´ or the SDX highspeed-SIO-code. Of course it´s not so fast like Happy or Speedy, because there´s no trackbuffer used, but better than without highspeed SIO. This patched version doesn´t support CP/M!

     

    Jurgen

    • Like 6

  16. Posted

    b) booting CPM, no matter which terminal I use (tt05 from trub, e.com or f.com), once I boot the CPM disk I get the 'Indus CPM 2.2 Rev 1.1, Hit return to continue' prompt but nothing I type does anything....

     

    Am I missing something else? I'm using an Incognito 800, with the programs loaded from SDX.

     

    Sounds like you didn´t patch the CP/M discs! Look into the manual and links to Trub´s website. Short how-to:

     

    - Copy the needed / wanted CP/M discs using any sector copier to real 5.25" floppy discs

    - Boot the CP/M tool from Trub

    - Use the repair function to each disc

     

    This procedure must be done at last to files "Indus RAM Charger CPM BIOS" and "Indus RAM Charger CPM Boot".

    • Like 2

  21. Posted

    Does cadj go straight to gtia pin17? Can it really reach 9v as is? The gtia datasheet specifies a max of 8v. If this is changed to 12v could this damage gtia?

     

    I think not. The circuit at the CPU cards for the 400/800 series will use 12 volt directly from the power supply PCB. There´s a 330k resistor in line, but when you turn the pot at the 12 volt´s end, you can measure - dependent on the manufacturer of the GTIA and if´s NTSC or PAL - something up to 9.5 or 10 volts. Never found a GTIA damaged - only the colors or whole picture disappear.

     

    IMHO the old NMOS chips are very robust.

    • Like 1

  22. Posted

    Not sure, but it would exist 12V in the circuit associated with the color adjustment. The O1 signal drives a charge pump which generates the right voltage for the color circuit (probably @ very small power level) it might be enough for SCART. Just a crazy idea that it might worth a look.

     

    Not so easy. And I wouldn´t recommend that.

     

    1.) you get max. 9.5 volts (from my personal experiences). That´s not enough for some TVs so switch to 4:3 mode

    2.) if you take the voltages for SCART etc. from the suggested point, the color setting ALWAYS will change. This have no effect on VBXE RGB or Sophia RGB output, but the normal video circuit and/or UAV is affected.

    • Like 2

  23. Posted

    Is a Boost Converter the only way to get 12V from the A8 motherboard? I ask as it would be nice to give SCART Pin 8 the correct voltage (9.5-12V) to automatically shift to an 4:3 aspect ratio when using that type of medium to carry the VBXE output. From very blurry memory I seem to recall a fairly compact circuit requiring an oscillating, inverse buck converter but that seems a bit much just for this application. I wonder if there are any modern DC-DC converter IC's that would do the job on a slightly more compact scale?

     

    I use DC/DC converters in SIL package for this reason. Look for "DC/DC converter 0512". They were made from Murata, Traco, etc. - Example items @ ebay UK: QDC1S-0512S or Murata

     

    These SIL adapters offers 42 mA or more, but you need only 10 mA for usual SCART televisions, so take the cheapest one.

     

    The advantage: No PCB needed and small. I use them for my VBXE installations. It´s not the cheapest way (you get also open PCBs from china for 2 bucks), but safe and easy to install.

    • Like 1

  24. Posted

    Thanks for the interesting article. I don't see the 230ms value in the article (it's really on page 50, right?). But it may be buried somewhere on the listing and it is difficult to follow for those of us that don't read german.

     

    I read the article (and the part 1 in the previous Atari Magazin), but there´s no part talking about precompensation. Only the rotation speed of 208 ms (milli-seconds) is named, as you already mentioned.

AtariAge
Forums
Store
General
Follow AtariAge

Copyright ©1998-2021 AtariAge

×
×
  • Create New...