Amstrad MEGAPC

Discussion in 'Retro & Arcade' started by Reaper, Dec 3, 2010.

  1. Reaper

    Reaper Member

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    Alright, thanks to bj74cruiser, I now have a mega pc.

    In short, it's a 386 computer & sega megadrive in one.

    Now, I thought that due to lack of photos on the rest of the internets, I'll upload some internal pictures here.

    You can search for external photos, I currently have it apart. Yea, I havn't even powered it on yet, I pulled it apart instead. I tend to do that. :D

    http://i96.photobucket.com/albums/l186/mv75/Image0124.jpg

    Motherboard picture. FINALLY! Someone has posted a picture of the actual motherboard. About frigging time they just stopped showing their megapcs off and actually showed something useful I say. :D

    http://i96.photobucket.com/albums/l186/mv75/Image0127.jpg

    Bottom left, video card area. Looks to be some sort of WD 90c paradise card, 2x memory chips with 2x 4464 empty sockets with "vga memory expansion" screen printed on. If someone has more patience than me to find actual datasheets, the chips on there are aaa1m304p-08 I guess they are 64kx8 80ns chips giving 512KB for 4 of them. I have quite a few spares of these chips to plug in.

    To the top right is a vga disable jumper. Yea, I'm going to try that and plug another vga card in instead. Well, maybe.

    To the bottom left, the pin row is where the ribbon cable from the megapc card plugs in.

    To the bottom right is a 3 bank of jumpers labelled 16color, 256color and non-int. Now this one is interesting, the 16color and the non interlaced ones are jumpered, the 256color one is open. Maybe it'll affect the mega drive output?

    http://i96.photobucket.com/albums/l186/mv75/Image0128.jpg

    Ram slots. Interesting is the empty solder joints for 4 more sockets. If I had the actual sockets, I'd try and solder 4 more on. Anyone got leads for those? Oh yea, Co-processor socket too. Anyone got a spare?

    http://i96.photobucket.com/albums/l186/mv75/Image0130.jpg

    Megapc card itself. Yes, 8 bit. For power only I think the edge connector is.

    This one is interesting, it appears to have that red "do not remove" thing over an edge connecter just like the megadrive2 IIRC, has internally. I forget what it's for, anyone elaborate?

    Ok, on the left, it seems that side is a sound card. It has a yamaha chip.

    The big rectangle is a z80 cpu.

    The middle is a "sega" chip and the right is a motorola 68k.

    The long black strip is a sort of edge connector that plugs into the front interface card.

    http://i96.photobucket.com/albums/l186/mv75/Image0131.jpg

    "inner" of the front interface card. That is where the megadrive card plugs in.

    http://i96.photobucket.com/albums/l186/mv75/Image0132.jpg

    "Outer" side.

    Joystick ports, cartridge port, reset button, mega/pc select switch and a volume slider.

    There is also a microswitch above the cart port, dunno what it's for, it's depressed when installed. EDIT: I just figured it out, when a cart is installed it would depress that. I guess that is the "power" switch for the megadrive side.

    Oh yea, the hole in the card is where the red edge connector on the megadrive isa card slots through. On the front of the computer where it says megadrive compatible, or whatever, that panel is removable and has that covered edge connector behind it.

    Anyway, ask more questions while anyone wants to as I'll have the board out for a little while longer as I'll re-replace the battery as, sorry bj74cruiser, but it was a pretty crap solder job that I'll re-do properly. :)

    Oh yea, the size of the machine is pretty small too. Only about another ~3 inches more from the top of the motherboard. Quite a small computer. Maybe about the size of a matx machine, but slimline.
     
    Last edited: Dec 3, 2010
  2. Asteroid

    Asteroid Member

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    Oh yes, finally some properly interesting old shit. :D
     
  3. Mau1wurf1977

    Mau1wurf1977 (Banned or Deleted)

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    Did it come with a monitor? I heard you need a multisync CRT that can do 15 KHz or something like that...

    Does it work?
     
  4. OP
    OP
    Reaper

    Reaper Member

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    Should work, bj74cruiser had the pc side working. I'm in the process of getting a megadrive game or two and a controller, then I'll test that.

    Monitor, yea, I have an nec multisync. :)

    But no, I havn't powered it yet myself, as I pull stuff apart instead.
     
  5. Mau1wurf1977

    Mau1wurf1977 (Banned or Deleted)

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    Coolies! Looking forward :)
     
  6. breech

    breech Member

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    I always wanted one of these or a megaplus, nice score.I wonder if it has a game built-in like sonic 1 or super hang-on? Be sure to remove that battery before it leaks.
     
  7. OP
    OP
    Reaper

    Reaper Member

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    Well if you outbid me in the sale thread here for it..... :)

    From a youtube vid I've seen, nah, no inbuilt games.

    The battery had already been replaced with a nimh one, but I just have to tidy it up a bit since I now actually have the motherboard out of the case. It wasn't easy at first, took some fandangling and prying to get the megapc card out. It definitly wasn't for the faint hearted that's for sure.

    I'm eyeing some auctions on ebay and maybe going to gametraders soon to get some megadrive stuff. I currently don't have any as I got rid of it all a while ago as I didn't want to collect it. Ah well. At least I only need a few games and controllers this time.



    Oh yes, more on the pictures, on the megapc card picture, the thing above it is the inside of the front face. Yea it's upside down.

    Floppy drive hole is obvious on the right.

    On the left is the holes and stuff for the mega drive side.

    At the top is the two holes for the pad connectors, small oval is the reset button and to the right of that is the switcher for mega / pc selection. It's moved when the front face panel is slid along. Above that is the volume control slider.

    In the middle of what looks like a cart hole is what the red capped edge connector fits in. It is actually sealed on the outside although the picture suggests otherwise. And as I mentioned first post, that middle section is removable.

    Below that is the spring loaded twin panels where the cart slot actually is.
     
  8. breech

    breech Member

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    I wont be bidding, I have about 20 other projects going right now lol. BTW you will need a monitor that can sync 15 + 31 khz. NEC multisyncs work with practically anything else you can throw at them.
    Link 1 Link 2 Otherwise there are some new scan doubler options that may work for you.
     
  9. Nitephyre

    Nitephyre Member

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    WTF, Amstrad made a Megadrive on ISA card for PCs? Wow, that's cool :D
     
  10. bj74cruiser

    bj74cruiser Member

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    I have just replaced the battery before I sold it to Reaper so it should be good for a long time
     
  11. bj74cruiser

    bj74cruiser Member

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    I actually had this running on a 15 inch LCD
     
  12. OP
    OP
    Reaper

    Reaper Member

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    Yep, battery is a good one. My personal favorite choice, a varta 3.6 nimh. I highly recommend it and have used it on my 2 286 motherboards here. Short of doing a cr2032 mod, I'd choose nothing else but this battery. I wouldn't and don't am bothered with external AA batteries either as they can and do leak.

    Monitors yea, I fired it up last night hooked to my 17" samsung lcd, it displayed fine, but in games such as elite it would flick off and on at intervals when the screen was animated.

    So I ripped out my nec multisync this morning and fired it up, graphics displayed perfectly. I switched it to mega mode and hit the micro power switch near the cart slot and the display stayed on, so there is hope it'll work fine. I just have to wait for a megadrive game I got off ebay last night to arrive. I also have to get some controllers too.

    Other stuff:

    I put a jumper on the vga disabled jumper on the board and ran my trident card just fine.

    Now this is where it gets tricky.

    I ran it without the megapc card plugged in and it displayed and operated just as a pc just fine.

    I then plugged the megapc card in and it went into a 2 colour only scheme. It was just mono display.

    Now, I re-enable the onboard graphics and take out the trident card. Using the onboard video it needs the megapc card in or there is no display at all.

    Oh yes, the adlib sound works just fine when I plugged in some 2.1 speakers in the jack on the back of the megapc card (that half of the card is a sound card). Next I've been thinking to get a p2/p3 slot1 cpu and set up my bh6 board with winxp or something and try plugging that megapc card in and see if it's detected as an adlib sound card.....

    Oh yea, I upgraded the video memory too, it's now got 512KB of video memory.

    I also discovered a great information tool, quarterdesk manifest. It tells me a lot about well, everything while in dos mode. I used it to confirm the video memory upgrade.

    http://www.jumpjet.info/DOS_Lives/05/Utilities.htm

    About the third one down, mft.zip
     
  13. IamDan

    IamDan Member

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    Awesome man.. A mate of mine used to have one. Was cool to have the best of both worlds.
     
  14. OP
    OP
    Reaper

    Reaper Member

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    Alright, got a megadrive cart in the mail today, I tried it, it displays, but is "out of sync". :( Had a look at the specs and it seems my multisync is from 31khz and up, xv15. Bummer.

    But for the sound, no need to fangle with the vga cord to figure it out, it outputted through the headphone/speaker jack just fine.

    I did find this though;

    http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=120457605985&ssPageName=STRK:MEWAX:IT

    Looks like it should work. Anyone else find one cheaper?
     
  15. Mau1wurf1977

    Mau1wurf1977 (Banned or Deleted)

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    I'm sure it will work, but you might not be totally happy with the result. I had a similar product for hooking up a PSOne to a PC monitor and while it worked the image wasn't perfect.

    But finding a 15 khz capable monitor is not easy either...
     
  16. OP
    OP
    Reaper

    Reaper Member

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    Just wondering on that compro you bought, it accepts 15khz signals right?

    I was thinking of getting one anyway after seeing what you did with yours and that vga to rca box for recording videos and having a go myself on some stuff, but anyway, if it does, then I might try getting a vga to rca straight cord and try that.

    Maybe something like this:

    http://cgi.ebay.com.au/VGA-SVGA-3-R..._Accessories_Wires_Cables&hash=item4aa2f70924

    I know it says tv out through vga connector, but a signal is a signal right? I know that isn't entirely true as there is ttl and analog, man, this is doing my head in.

    Oh yea, it was pointed out to me on vintage computer that that converter I linked two posts above was for analog cga as well so may not work. Ah! It's hard to find a digital to digital upscaler.

    At least I know the machine works fully though. I saw the cart graphics and little sega logo, torn / shifted, but seeable, and sound working. :) I also have a real megadrive ONE :D coming too with more games, but more importantly I bought it for the controllers. Can't believe it was cheaper to buy that console with 5 games, two controllers than it would have been to buy just two controllers and a game or two.
     
  17. Mau1wurf1977

    Mau1wurf1977 (Banned or Deleted)

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    Be careful with these "no logic" adapters:
    The Compro device I bought is a S-Video capture card, it wouldn't do much for you.

    Do you know more about the type of signal that comes out from your MegaPC?

    Some possible options for you:

    1. I reckon an old Amiga Monitor would work. They are 15 KHz though you need to sort out the connection into the monitor. In europe we had RGB Scart plugs, and I'm not sure what the Amiga Monitors over here came with.

    2. An old CRT TV should also work (They take 15KHz RGB just fine). But again unsure what RGB connections Australian TVs had. AFAIK you guys didn't have RGB Scart plugs.

    3. 2nd hand LCD monitor which takes 15 KHz signals. They do exist it seems, just needs some research.

    4. 2nd hand Multisync CRT monitor
     
    Last edited: Dec 9, 2010
  18. OP
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    Reaper

    Reaper Member

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    It's a digital 15khz signal. It outputs through the onboard paradise 90c video.

    The crt tvs I have here have either composite or svideo inputs.

    One would think actually that a vga to svideo converter as I mentioned just before, like the one you got (the ebay link you have in your thread) should work if then plugged into a tv, or into the compro, both of which I am planning to buy anyway after seeing what you did with your videos. :) Plus the compro has game consoles listed as being a device to hook up along with vhs, etc.

    I've probably missed something, but anyway. :)
     
  19. Mau1wurf1977

    Mau1wurf1977 (Banned or Deleted)

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    The thing is I don't know if my VGA to S-Video box works with a 15KHz (it's analogue by the way :) signal and I have nothing here to test this...

    That 15KHz scaler you linked earlier looks like the solution, but boy it's quite expensive...

    Only cheaper one I found is this RGB/Scart to Component box: http://cgi.ebay.com.au/NEW-SCART-RG...457?pt=LH_DefaultDomain_0&hash=item3362ac07d1

    That 15Khz scaler you linked, does the input pinout of that box match the pinout of the VGA cable on the MegaPC? If the pinout lines up, at least you wouldn't have to build your own cable.

    Hmm well the more I think about it, that scaler will be useful for any other RGB console you might get down the track. Doesn't look that expensive anymore if you put it into perspective...
     
  20. OP
    OP
    Reaper

    Reaper Member

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    Cool, added to watch list.

    I'll have to check it out later on the pinup line ups, but I'm sure it would match.

    I just did a big blitz just then and bought a heap of stuff including the vga converter and a c200, so I'll just wait until it all arrives and test it out. But as I mentioned, I wanted those items anyway to get some video from my 286 etc anyway like you did with your wingcommander videos. :) Seems easier than trying to record on video camera, and the only video camera I have is my crappy phone one.

    Oh yea, I ordered a componet cable for the MD1 I'm getting as well, just for the shits and giggles of trying that on the compro, plus it'll be easier to hook to a tv if I ever wanted to.
     

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