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Education Adventures in retro games/systems

Discussion in 'General' started by Byron C, 15 Apr 2020.

  1. Pete J

    Pete J Employed scum

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    (Singing) *We don't need no USB ports*

    Three questions:
    • Are you going to remove the QC sticker on the keyboard?
    • Why did your uncle stub a cigarette out on it?
    • Did you murder your uncle shortly thereafter?
     
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  2. Byron C

    Byron C And now a word from our sponsor

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    • Probably not, it's under the top shell where it's out of sight. I have a lot more work to do on the keyboard though, so if I change my mind then it's not exactly a hardship to get rid of it.
    • Absent-mindedly smoking over the machine :miffed:... When you smoke inside you smoke near/around/on everything, cigarette burns are not uncommon...
    • Probably not; these days I would, but I was in my early teens when it happened! :grin:
    EDIT: Apparently the swear filter can't distinguish between different meanings of the word "f@g" :grin:
     
    Last edited: 17 Apr 2020
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  3. ElThomsono

    ElThomsono Well-Known Member

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    An interesting read, thanks for posting.
     
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  4. Byron C

    Byron C And now a word from our sponsor

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    So these arrived the other day...

    TOS v2.06 ROM chips, courtesy of Jays Retro Computer Sales on eBay

    [​IMG]

    So remember when I mentioned W102, W103, and W104? Well, I need to change those, since the current jumper positions will not work with these ROM chips.

    It turns out that they are indeed through-holes in the board which have been filled with solder. So... soldering iron time.

    Putting a cherished childhood computer under the soldering iron is a hairy experience to say the least! Yes, I did clean up the flux gunk afterwards :thumb:

    [​IMG]

    So now instead of these zero-ohm resistors used as jumpers...

    [​IMG]

    I now have these header pins installed

    [​IMG]

    Why 2.54mm header pins, I hear you (not) asking? Well, because you can put jumpers on them like this

    [​IMG]

    There are five different possible jumper settings, depending on both the ROM version and the specific EEPROM/EPROM/ROM chip type you're using. TOS v2.06 has some incompatibilities with older games/software, so if I ever want to change ROM version I just have to pop the other chips in and change jumper settings. No need for custom ROM switching boards, hardware modifications, de-/re-soldering, etc... just a simple jumper change :happy:

    And here's v2.06 installed...

    [​IMG]

    Luckily those jumpers just fit under the floppy drive & floppy drive emulator!

    [​IMG]

    Of course I'm not going through all that without testing it....

    Atari 'Fuji' logo and RAM test on boot - that's a v2.06-only feature, so.... WIN! :grin:

    [​IMG]

    And of course I have to let it boot to the GEM desktop... There is no version information displayed in the 'About' menu (thanks Atari :rollingeyes:), but... that chequerboard desktop pattern is also present only in v2.06

    [​IMG]

    Here's what older versions look like - a solid lurid green. The v2.06 version is much easier on the eyes!

    [​IMG]

    While I was 'under the hood' I took the opportunity to check which DMA chip I have. And it's bad news, I have the version that is known to have corruption issues with modern hard drive adaptors such as the Ultra Satan - see here for some more detail from the designer of the Ultra Satan: http://joo.kie.sk/?page_id=250

    [​IMG]

    It's not the end of the world, the Ultra Satan is not the only modern hard drive solution out there.

    So. What's next for this system? Well in terms of actual physical hardware mods... I think that's pretty much it, to be honest. Unlike Amiga systems there is very little advantage to be had from installing hardware accelerators. They are available - two examples here and here, pretty sure both are 68020-based - but at the moment I can't see much point in them. They only really accelerate GEM (as in, desktop-based) software. Unless of course you're interested in running alternative OSes such as MiNT, but you're really better off with an Atari TT, Mega STe, or a Falcon 030 for that kind of thing. (Oh gooooood, how I'd love to get my hands on an Atari Falcon 030! They're rare as hen's teeth these days and regularly sell for £700/£800 or more!). There just isn't the software/OS market for the Atari ST range that the Amigas had (and still have).

    I do want to run some GEM software, which is why I've upgraded to TOS v2.06 in the first place. It's a pre-requisite for a lot of addons such as the NetUSBee or the Ultra Satan as there's better driver compatibility. I do want to play about with a hard-drive based Atari STe since I never had one growing up - I want to see what this machine can do :grin:. To that end, the next add-on I'll get is a NetUSBee: it slots into the cartridge port and adds both an ethernet port and USB ports to use USB devices as a hard drive.

    A NetUSBee can wait though, because the real priority for me at the moment is an upscaler. I can't really use any of these classic systems at the moment; it's not practical to have them all in the lounge, and in any case modern LCD monitors & TVs suck at deinterlacing and upscaling. You really need an external device to get better quality. Getting your hands on an LCD - or even an old CRT - monitor that definitely supports a 15Khz vertical sync frequency is not an easy task these days... They're out there but they're sought after by people like me and are therefore expensive...

    I think for now I will stick with one of the ubiquitous RGB SCART to HDMI boxes and see how I get on. If I really start doing a lot more with these older systems - streaming, collecting, etc - then it'll be worth investing in something like the OSSC. They're pricey at £150+, but they are very good. There are better quality upscalers out there, such as the Framemeister xRGB-Mini, but they are even more expensive... :eeek:
     
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  5. Byron C

    Byron C And now a word from our sponsor

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    OK... I may have made a breakthrough...

    I kept this old Sony monitor from many many years ago... I looked up the specs a while back and it says that the minimum vertical sync frequency it accepts is 31Khz, which is normal for a VGA monitor... but no good for systems that use 15Khz such as my STe, my PlayStation, my Megadrive, etc..

    [​IMG]

    But I came across this youtube video of someone demoing some games on an Atari Falcon 030. He's using the same monitor... in the low-resolution ST/STe video modes.... huh...



    So I start doing some googling to find out what vertical sync frequency/frequencies the Falcon used. I couldn't really find anything definitive, but I did find this buried in the video comments

    [​IMG]

    'works superbly with Atari STE and Falcon 030 computers'...

    *blink*

    Youwotmate? You're telling me this monitor I've had sat here for years - for longer than I've had the Atari out of the loft - can accept 15Khz vertical sync signals and all this time I didn't know?! You****ingwotmate?!

    OK so I lied earlier. An upscaler will not be my next purchase, this will be my next purchase

    [​IMG]

    It's an adaptor that properly wires up the Atari 15-pin DIN video connector to a standard VGA connector to use with a 15Khz-capable monitor. And it's only £32 (plus shipping).

    An upscaler plus LCD monitor or TV is a good compromise, but the gold-standard for retro systems is using a CRT display. If this works I will be chuffed beyond belief. It'll have to wait until next payday, but.... EXCITE

    [​IMG]
     
  6. Byron C

    Byron C And now a word from our sponsor

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    I've posted bits and pieces on various social media channels, and various other threads here and there, but I really should update this thread!

    This little dongle then....

    [​IMG]

    It seems it was already in high-res mode when I got it. Woohoo! That's my Atari STe in high-res on a VGA CRT! Bask in its monochrome glory! :grin:

    [​IMG]

    But we need low-res mode for games - only GEM desktop stuff will run in high res mode. So let's see if this CRT really does support a 15KHz sync signal.

    To quote James May, "Oh cock".

    [​IMG]

    Well that's a kick in the nadgers.

    I had a re-think. I was going to need a solution to use all my other consoles with a modern screen anyway. I already have a working CRT screen and these systems just don't look right on an LCD, I'd like to keep using the CRT ideally...

    Enter the GBS8200:

    [​IMG]

    This is an upscaler originally designed to convert arcade cabinets to use modern monitors. It takes 15KHz RGB signals and spits out VGA at the other end. The plan is to have this as the centre of a universal SCART-to-VGA adapter/upscaler. Plop an RGB SCART signal at one end and get an upscaled VGA signal at the other.

    The quality with these boards is a little iffy at the best of times so I'm going to need to do something about that. The simplest hack is some copper tape over the traces between the RAM chip and the main processor.

    I don't want the easy solution though. In that spirit, enter the NodeMCU development board for the ESP8266 microcontroller. Also welcome the gbs-control firmware to the party, but I can't show you a picture of that...

    [​IMG]

    Why do I want this? Well the GBS8200 has I2C programming pins exposed and a header to put it in 'firmware flashing' mode. If we hook up the NodeMCU to the GBS8200 via I2C then the the NodeMCU, running the gbs-control firmware, can take over control from the microcontroller on the GBS8200. Apparently there are a ton of improvements over the stock firmware, including running the memory bus more slowly so that the copper tape hack is not needed. The really cool thing though is allowing you to 'pass through' the original resolution to the output VGA device without doing any upscaling - hell yes! I know my monitor can take 240p resolutions, I used to run games at 320x200 on back in the day.

    Also, we need to do something about the sync signals. The SCART system uses the composite video pin to carry the sync signal - that's why it's called 'composite' by the way, it's horizontal sync, vertical sync, and video signals all on one pin. Consumer AV gear with SCART can deal with this. The video element of composite video gets stripped away leaving what's known as composite sync. The GBS8200 apparently has trouble with using the composite video signal for sync, so it's far better to feed it a clean CSync signal which has been stripped of video.

    That's where this comes in:

    [​IMG]

    It's actually designed for converting from SCART to BNC, but as well as breaking out each of the video & audio pins it handily includes a sync-stripping circuit built in to give you a nice clean CSync signal. Neat.

    Well... it would be neat if it actually worked with my STe... :waah:

    [​IMG]

    I also couldn't get the NodeMCU to establish an I2C connection to the GBS8200, but that's entirely my fault. My cack-handed soldering skills are totally out of practice and I hosed the pads for the I2C pins on the GBS8200 board :wallbash:. I hate trying to clear through-holes that have been filled in with solder...

    My own cack-handed-ness aside, I could not get the GBS8200 to detect the Atari STe's video signal, even when the NodeMCU wasn't in the loop and even when the sync-stripper on the SCART board was switched off.

    I gave up after several frustrating hours and came back to it in the morning. I bypassed the SCART board and wired the GBS8200 video harness directly to the SCART pins and, just on the off-chance, I used a PlayStation instead of my STe to test...

    SUCCESS! Sort of!

    [​IMG]

    Sync was very hit and miss - I presume that's the GBS8200 having trouble with using composite video as the sync signal, so I definitely need to get a sync-stripper back in the loop. Nevertheless, let's try this configuration with the STe.

    Balls. Same as the night before!

    [​IMG]

    OK, let's put the STe to one side for a moment - maybe there's some weirdness going on with the STe's composite signal, maybe the GBS8200 is freaking out with a 5v TTL-level sync signal.

    After some thorough reading of the gbs-control wiki, I discovered a very good forum post detailing how to get a SCART signal to work with the GBS8200. The TL;DR is that most people aren't terminating the video signals properly in their sync strippers and are just implementing the LM1881 datasheet verbatim.

    Instead, this LM1881 implementation is offered, which is apparently much closer to what would be inside a piece of consumer AV gear with a SCART input:

    [​IMG]

    So. I could just solder this circuit together 'dead bug' style. I could just slap it on some veroboard/stripboard. Both of those options require more cabling and I want as little cable in the loop as possible - the more cables we have the more chance we have of interference...

    Instead of that I designed a PCB:

    [​IMG]

    The main purpose of this board is to implement the sync-stripping circuit shown above, but while I was at it I thought I might as well add some headers so that I can plug the NodeMCU directly into this board for a neater solution. I'll still have to connect the I2C pins to the GBS8200 with header pins, but it's one fewer board to mount inside a case.

    Right now I am waiting on parts, which is the bane of these kind of projects. 5x LM1881 ICs and 2x PCB-mount SCART sockets were delivered today; I am waiting for a replacement GBS8200 and the PCBs are on their way from China. I need a capacitor set since I don't have any components here at all, but I can get that cheap on Amazon.

    So I guess that's it for now! If you've made it this far, I congratulate you :lol: - thank you for reading!
     
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  7. Byron C

    Byron C And now a word from our sponsor

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    Alrighty, time for an update!

    [​IMG]

    Got mah boards last week, but didn't have time to play! Pretty damn impressed at what you get for $2 (plus $12 shipping), especially considering you get 5 copies...

    [​IMG]

    Spotted a bug though... I didn't route out the 'debug' pin - this is part of gbs-control and it's not required for basic operation, but it does allow gbs-control to fully take control of the entire process. Never mind, I want to do a rev2 anyway: I need to add a cutout for the plastic clips that some PCB-mount SCART sockets have, and now that I see the physical thing in my hand I see how I can drastically reduce the overall board size.

    Tonight I finally had chance to get an 'alpha' build assembled! Only the essentials hooked up at the moment, I'm more interested in testing the sync-stripper right now.

    [​IMG]

    Honestly the most pleasing part is that I absolutely nailed the footprint for the SCART connector! So pleased with that!

    [​IMG]

    I need to add the aforementioned cutout, but other than that it fits....

    [​IMG]

    All wired in for a first test run...

    [​IMG]

    So... Does it work...?



    You bet your sweet arse it bloody works! :grin: Absolutely rock solid picture, no 'jumpiness' or jitter whatsoever. It's a little dim, but that's normal for the stock GBS-8200 configuration - I'm not concerned about that, the gbs-control firmware will sort all of that in the 'final' version.

    And just for those who prefer still images...

    [​IMG]

    Previously when I wired directly in to the GBS-8200 RGBS pins from SCART, I could get a very 'jumpy' signal working with the PlayStation but the STe would not play ball at all. So. Does the STe work with my custom sync stripper then...?



    Yes. Yes it does work. :clap: You can't see it, but right now I am happy-dancing. Although not too vigorously because my back is already a bit sticky... (Did I tell you how ****in hot it is right now? Oh, I did? Never mind...)

    Obligatory photo of the STe working:

    [​IMG]

    Onwards! Next step is a 'beta' build of the current hardware: add 2.54mm pin headers for all off-board wiring, 2.54mm socket strips for the NodeMCU, and add the I2C pins to my second GBS-8200 without trashing the solder pads this time (ok, ok, I've learned my lesson: lead-free and leaded solder don't play nicely, I know...). While I'm waiting on the parts I need, I'll get on with Rev2 of the PCB: I need to add cutouts in the board for the SCART clips, the SCART socket needs to come forward (those lugs on the housing need to be either over the edge of the board or flush with it), I need to add the pin for the 'debug' connector, and I want to drastically reduce the overall footprint of the board.

    Time for a cool refreshing beer*!

    *OK you got me it's Budweiser, which is only marginally better than fizzy piss.
     
  8. Guest-44638

    Guest-44638 Guest

    Not sure it's safe to enquire how you know this...
     
  9. Byron C

    Byron C And now a word from our sponsor

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    Pretty simple really...

    [​IMG]
     
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  10. Guest-44638

    Guest-44638 Guest

    Knew it wasn't safe... :eek:
     
  11. Dr. Coin

    Dr. Coin Active Member

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    You were looking for help with a enclosure for an earlier design, will you need help for this updated converter?
     
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  12. Byron C

    Byron C And now a word from our sponsor

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    I'll be busting out my rusty CAD skills when I've got down to a final revision :grin:. To be honest the enclosure I was looking at will pretty much do the job, I'm just going to have to re-locate the case cutouts and the stand-offs. Really regretting the fact that I got rid of my 3D printer now!
     
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  13. Pete J

    Pete J Employed scum

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    I was trying to find a GIF of the Malcolm in the middle bit where they're in the car on a really hot day and he peels himself off the leather seat, but I had no luck.

    So, y'know, just imagine I found it and watch it mentally. In your head.
     
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  14. Byron C

    Byron C And now a word from our sponsor

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    Can do :grin:
     
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  15. Byron C

    Byron C And now a word from our sponsor

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    New PCB revision is done!

    [​IMG]

    SO MUCH SMALLER. I can probably make it even smaller again, but why push it? I've already shaved 30mm off one edge and the shipping & customs is still by far the most expensive part of this process: £1.59 for the 5x boards and £10.57 in shipping & customs charges.

    Also: Yeah I put my logo on it, what of it? :grin:

    This time I opted for a black solder mask since it made zero difference to the price. Plus, everyone knows that black PCBs are just so much more cool :hip:

    [​IMG]

    The "JLCJLCJLCJLC" text on the board is so that JLCPCB know where to put their order number; you can ask them to remove the order number but it adds a lot to the cost - but if you add that text to your solder mask then JLCPCB will put their order number there instead.

    EDIT: Oh ffs... I didn't add the cutouts for the SCART socket clips, did I? :duh: **** it, I'm a developer so it's a feature now, not a bug. :grin:

    In all srsnss it's not a deal-breaker, you just have to cut off the clips if your chosen SCART socket has them... The clips do add some strain relief, but with that many solder points I'm not too worried about long-term mechanical reliability. It's not like this is going to be a retail product!
     
    Last edited: 2 Jun 2020
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  16. Byron C

    Byron C And now a word from our sponsor

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    And here's what the rev1 SCART interface board should look like while fully populated!

    [​IMG]

    The black wire is a classic bodge wire: there's no convenient point on the GBS-8200 board to solder it to so it's soldered directly to the chip leg; I forgot to add the footprint for it in the original board, so it's soldered directly to the pin of the microcontroller socket!

    [​IMG]

    All seems good so far!

    [​IMG]

    I also tested out the VGA input with the Atari STe adaptor I bought a while back and it works great in low-res mode; the GBS-8200 won't sync in high-res mode, because the VGA-in isn't actually designed for VGA signals, it's designed for CGA/EGA.

    [​IMG]

    Turns out that I still suck at Golden Axe. I'm not entirely sold on having the monitor set up over there. I need to move the cabinet quite far away from the wall and there's no easy access to decent speakers. I might bring it back onto my desk, but that would mean no secondary PC monitor...

    [​IMG]

    I've been using one of those multi-voltage mains adaptors to power the GBS-8200, but right now I also need that adator to power both the Mega Drives and PSone. I don't have any other 5v barrel-jack mains adaptors, but I do have plenty of 12v ones with the right tip size and I also have plenty of MicroUSB cables and USB mains adaptors...

    Witness the unholy union twixt USB cable and DC barrel jack! It should be fine, as long as whatever USB mains adaptor I use isn't too smart and doesn't actually follow proper USB spec (USB power sources are supposed to limit available current unless the client device negotiates).

    [​IMG]

    Rev2 SCART interface PCB is on its way, and I've also ordered some more SCART sockets as well as a couple of panel-mount 3.5mm audio sockets! Once I've got the Rev2 SCART interface in my grubby little hands I'll fire up my rusty CAD skills and get to designing a case!
     
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  17. Dr. Coin

    Dr. Coin Active Member

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    I was going to call you out on protocol, but you're ahead of me.
     
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  18. Byron C

    Byron C And now a word from our sponsor

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    I do have a proper 5V 2A DC adaptor on the way, so this isn't permanent - but it'll do for a quick temporary hack :grin:
     
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  19. Vault-Tec

    Vault-Tec Green Plastic Watering Can

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    Awesome !
     
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  20. Byron C

    Byron C And now a word from our sponsor

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    Ran the 240p test suite on a softmodded Wii this morning, and all the test patterns look great - including the drop shadow tests

    [​IMG]

    After re-arranging things a little I thought it worth double-checking which of the Playstations work.

    This PSX is in rough shape :(. There are no case screws for it and it does not detect discs :(. I would love to get it back to its former glory because this was my Playstation, but it might prove more cost-effective to just buy one that works... I don't know yet....

    Also those memory cards aren't great either. One of them has a snapped case and both of them only work intermittently :(.

    [​IMG]

    This fat PS2 however works just fine! The disc drive doesn't sound great when trying to read PSX discs, I'm going to try it with PS2 games shortly but I wouldn't be surprised if the drive dies before long...

    Dat FF8 theme though... <3

    [​IMG]

    And this PSone also works just fine! No wonky noises from the drive in this at all!

    [​IMG]

    Time for some more cleaning I think. Starting with the PSone and its controller. There is absolutely zero wasted space in these things!

    [​IMG]

    [​IMG]

    Clean and shiny! Going to leave it dry at least overnight before I put it back together. There are lots of nooks and crannies for water to hide in, and trapping water inside it is just asking for it to be corroded...

    [​IMG]

    You would not believe the utter filth that was encrusted into these buttons... *boak*...

    [​IMG]
     
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