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Re: Amstrad Mega PC

Posted on 2020-09-09, 12:18

By the way, since you seem to own flash carts, there's a small homebrew scene for the Mega Drive/Genesis .. Project MD looks quite nice, for example. A few commercial games, like Pier Solar or Tanglewood were also made recently. Yes, have been supporting these projects - its nice to have original …

Re: Amstrad Mega PC

Posted on 2020-08-27, 08:24

thanks for sharing this! yes this should work just fine - I will try it tomorrow evening on the 386sx board , it should boot without issues Very exciting news 😀 - have everything crossed that all goes well for you keropi and we get to see a what an stock original megapc plus could do performance …

Re: Amstrad Mega PC

Posted on 2020-08-16, 13:25

Some photo's from the testing... P8160250.JPG Myst via Win3.1 works ! - the CD ROM drive struggles during the startup video, but the game itself plays fine and looks good . This is certainly a result as my attempt with the old 5420 graphics chip found it was very difficult to play - now the only …

Re: Amstrad Mega PC

Posted on 2020-08-16, 13:13

Will have a bit more to report at the end of the week as I've found a local PCB maintence firm who's going to do the graphics chip replacement for me - and I have a few upgrades in progress at the moment - until then I'll tantalise you all with the image of the NOS 5428 chip I managed to find for …

Re: Amstrad Mega PC

Posted on 2020-08-16, 12:57

I'm strugging to work out the +/- pins for the Ext Bat on the motherboard, using my aging multimeter, the resistance appears to be approx zero on pin 4 (furthest from the edge of the MoBo) which I think means that's negative? This is based on what I read at http://pc-restorer.com/replacing-cmos- …

Re: Amstrad Mega PC

Posted on 2020-08-13, 20:28

Hello there. I'm the one who made the post linked above. I've upgraded to a 486SLC33 motherboard since (the one with the CL5420 chip and AMI BIOS) but I still have the older PC7486SLC80 one. And the processor is indeed a Ti486SL 25Mhz as the following picture I've just taken of the naked …

Re: Amstrad Mega PC

Posted on 2020-08-12, 18:55

very interesting info Zalog about the 386sx board with a 486slc cpu... too bad we can't locate the correct bios - most likely the only change is the activation of the 1kb of cache LOL Looking into the whole issue has been a really interesting bit of Amstrad PC history, Indeed the whole of the later …

Re: Amstrad Mega PC

Posted on 2020-08-12, 18:20

I just watched him do the replacement and almost couldn't help talking and pointing at my screen... :D As for the fire, I'm thinking that was an exaggeration in the post before. When he turned it on, there didn't even seem to be any magic smoke. :) Agreed, my thinking is with these rare boards its …

Re: Amstrad Mega PC

Posted on 2020-08-12, 08:16

I'm on the case with the battery. I have someone going to my aunts this week to get the base and undo it for me to see... I have a vague memory of infact replacing the battery as it didn't hold settings etc, maybe one of the reasons why it was going for £5.. I remember opening it and finding the …

Re: Amstrad Mega PC

Posted on 2020-08-11, 08:05

This thread is awesome! I found it when doing a search on upgrading the Mega PC with a 486slc.. I also need to get someone technical to open it and take out the battery! If my 7486slc board can't be found, i'd like to try to upgrade the original 386sx board processor, GFX etc.. so.. Are there any …

Re: Amstrad Mega PC

Posted on 2020-07-22, 12:43

However, in case it's not possible.. QuickTime 2.x can also use DCI if the driver supports it. 🙂 Display Control Interface was essentially Windows 3.1x-only (Win95 was planned to have DCI32, but it never really materalized). Some movie players like Xing MPEG Player also use DCI. . That's good to …

Re: Amstrad Mega PC

Posted on 2020-07-20, 09:11

Myst? You might be lucky then. 😁 It uses QuickTime VR and QuickTime 2.x (16Bit) has direct frame buffer support for certain VGA chips built-in, too! Just check the help dialog in QuickTime's Control Panel applet. 😁That's fab news, myst is one of my favourite games and being able to play it on the …

Re: Amstrad Mega PC

Posted on 2020-07-18, 15:27

allright - did the transplant and it was a success ! - SpeedSYS reported a bump in video memory from 3.085kb/sec to 7.850kb/sec - Wolfenstein3D benchmark gained 2fps , doom some ~1.5fps - these are cpu-bound so no surprise - win3.11 reported a massive boost in performance - as expected since 5420 …

Re: Amstrad Mega PC

Posted on 2020-07-16, 18:15

line-in #2 stays ;) also: https://i.imgur.com/RZcc1Zjl.jpg That's fab news, thanks for keeping the extra line in. The scan doubler connection sounds also sounds a very sensible solution - can't wait to see it in action 😀 Oooooooooh!!! Looks like your cirrus logic 5428 has arrived - guess we'll be …

Re: Amstrad Mega PC

Posted on 2020-07-16, 07:15

I've decided to go with a Backpack CD drive that connects through the LPT port. [...] Ah , a LPT cdrom... how does it perform? does it bring the cpu down on operation? A seconday line input can be possible but it must be further down the pcb This might not be an issue though since the megapc card …

Re: Amstrad Mega PC

Posted on 2020-07-15, 08:42

how will you connect the external cdrom? backplate of card is pretty much full atm though... I've decided to go with a Backpack CD drive that connects through the LPT port. I had thought of attaching to the IDE, but it requires cutting and when I thought about it the LPT option would be easier and …

Re: Amstrad Mega PC

Posted on 2020-07-14, 20:36

If you solder there a 8bit slot it will work - it will barely fit as the drive cage is in the way. Lack of expandability really hurt the system.... Yes, it does look very tight in there - probably too tight to do anything really useful 😔. I think your decision is the better option - will have to …

Re: Amstrad Mega PC

Posted on 2020-07-14, 09:31

I also noticed on schematic the vga chip is marked as "CL-GD542x" and not GD5420 specifically like all other ICs... so they just went for the cheaper option apparently! That's good, looks like there should be no problem adding a 5428 then :D BTW have you noticed the artwork on the reverse of the …

Re: Amstrad Mega PC

Posted on 2020-07-13, 08:16

So have been busy over the weekend....... Dropped in a Cyrix FasMath 33Mhz Co-processor - unfortunately the Cyrix logo is a bit dull so it doesn't photo well :-( _20200710_073346.JPG Added on a nice gold coloured heatsink onto the 486SLC - things are running much cooler now and it does seem to make …

Re: Amstrad Mega PC

Posted on 2020-07-13, 08:05

Ah even photos like these are great! thanks! I see there are missing details anyways due to photocopy It makes sense they modified a 386SX design since the 486SLC will just work in place of a 386sx all it needs is bios to enable that 1kb of L1 LOL Thanks for the jumpers, I was wondering what JP12 …

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