Author Topic: A CPC is Born! GX4128  (Read 10903 times)

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Offline Badstarr

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A CPC is Born! GX4128
« on: 07:13, 27 April 12 »
Hi to all!  ;D


After neglecting the GX4000 to Plus modification project a little of late, I decided to roll up my sleeves and get cracking on it again. Having had some keyboard issues which turned out to be a faulty membrane, I swapped the 464 keyboard for one from a dead 6128 I got from ebay a while ago (will get round to repairing both one day  ??? )


After soldering many, many, many wires to the GX4000 ASIC and CPU and various other places and soldering the other ends to a piece of PCB cut from a dead 464 mainboard, I had an Expansion Port rigged up which I tested with my trusty multimeter 1 or 2 (hundred) times. Testing complete I fired up the GX4000 and it still worked, always nice to see that blue and yellow menu screen! I have acquired an affection for it during this project!  :laugh:


For my birthday I got a nice shiny DDI-1 interface which the previous owner had been generous enough to modify it to use a 3.5" drive or HxC with and the interface powered by the CPC. After a quick test on my 464 I removed the DDI-1 Amsdos ROM and performed a little surgery on it so it was ready to use with the GX4000.


I plugged in the DDI-1, prayed to the CPC gods and after a deep breath I turned on the machine and it didn't burst into flames! Next I connected a disk drive (unfortunately still configured as DS1 for now) and popped in a copy of Fluff. An |B RUN"FLUFF later and... well check out the youtube video and you can see!  ;D  Excuse the messy desk etc!


Amstrad GX4128 Lives! or A CPC is Born! - YouTube


I haven't given up on making a Disk interface from scratch, I am still working on that, but as seems to be the case more and more these days I seem to have so much stuff to do, and it seems its usually car related!  :laugh:


Well next on the list for the GX4128 Rev. 1 (as I'm calling it) is to tidy up and get those exposed wires inside the case and integrate the Expansion Port as neatly as possible into the side of the case. In the meantime I will be putting together a nice straightforward guide on how I did all this, which I guess will be essentially a multi media version of The Cranium's guide.


Thanks for looking!  ;D





Proud owner of 464 GTM64 6128 GTM65, GX4128 and a 464/6128 Plus Hybrid a 20 year long ambition realised! :-)

Online robcfg

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Re: A CPC is Born! GX4128
« Reply #1 on: 10:39, 27 April 12 »
Nice work!


Glad you managed to get it up and running!  8)

Offline MacDeath

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Re: A CPC is Born! GX4128
« Reply #2 on: 13:48, 27 April 12 »
excellent, now all you have to do is to find a square monitor. :D


Also, is your machine equipped with Disk or Tape ?
GX4000 ... but disk is for 6, not 4... and it is 3" disk.

So technically it is a real GX6128 you have here.
PErhaps even 7128 (7 for 3"1/2 ?) or HxC ?
GXHxC128 then...ouch...

I was alway ashamed the GX4000 didn't have a Keyboard plug nor a proper extension port or even tape port.
there should have been an upgradable GX4000 instead of a 464PLUS.

And IMO it should even have featured 128K.
« Last Edit: 13:52, 27 April 12 by MacDeath »

Offline Bryce

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Re: A CPC is Born! GX4128
« Reply #3 on: 15:18, 27 April 12 »
You mean like the Atari XEGS? That's how the GX really should have been done.

Bryce.

Offline Badstarr

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Re: A CPC is Born! GX4128
« Reply #4 on: 16:33, 27 April 12 »
Thanks Robcfg and MacDeath!  ;D


It's certainly nice to have a new CPC with Plus features! I can sleep a little better knowing that its not a case of all eggs in one 464 Plus basket!


The model number I have chosen may seem a little strange however I used the following rationale. From what I can gather Amstrad Computers indicate the series by the first number, or prefix, in this case the machine is a GX4-000, in the case of a CPC the remaining numbers refer to memory configuration, however as you can see the GX4000 does not show its memory but as its no longer a simple GX4000 I felt that I should change the zeros to indicate the built in memory. As the machine does not currently have a built in disk interface I could not justify calling it a GX6000/GX6128. When the machine has all the bits in the box I plan on calling it a GX6128!


As for the monitor, I actually quite like the stretched out widescreen for some reason, I have adapted my GT65 to work with the Plus/GX but the 21st Century has spoiled me with super thin TFT screens! Space is at a premium on my work desk as you can see in the video so the GT65 has been stored away for now.


And I absolutely agree that the GX4000 should have offered some kind of upgradeability to a full Plus machine, I think it could have made quite a difference to its success as I think most of the potential buyers for the GX4000 would have been CPC users looking to upgrade and consoles were all the rage in the 90's.



Proud owner of 464 GTM64 6128 GTM65, GX4128 and a 464/6128 Plus Hybrid a 20 year long ambition realised! :-)

Offline Gryzor

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Re: A CPC is Born! GX4128
« Reply #5 on: 16:37, 27 April 12 »
[attachimg=1]


PS no sound then?

Offline Badstarr

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Re: A CPC is Born! GX4128
« Reply #6 on: 16:42, 27 April 12 »
Hehe  :laugh:  There is sound but the digital camera it terrible at picking it up also the speakers on the TV are a little wimpy but if you play the video full blast you should be able to faintly hear the sound just don't let the white noise deafen you!
Proud owner of 464 GTM64 6128 GTM65, GX4128 and a 464/6128 Plus Hybrid a 20 year long ambition realised! :-)

Offline Gryzor

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Re: A CPC is Born! GX4128
« Reply #7 on: 17:18, 27 April 12 »
Actually I was hearing some nice ambient noise, like it was added for effect to the video :D

Offline Badstarr

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Re: A CPC is Born! GX4128
« Reply #8 on: 17:29, 27 April 12 »
I know! Weird isn't it!? I have no idea why it makes that noise, I guess it could be the internal noise from the lens motor in the camera or just general electrical cross talk being picked up? It sounds like I have a server farm in the room with me! I will post another vid shortly with the TV full blast so we can hear the wonderful CPC sound  ;D
Proud owner of 464 GTM64 6128 GTM65, GX4128 and a 464/6128 Plus Hybrid a 20 year long ambition realised! :-)

Offline TFM

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Re: A CPC is Born! GX4128
« Reply #9 on: 21:20, 27 April 12 »
Greets to the good work :)
TFM of FutureSoft
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Offline Badstarr

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Re: A CPC is Born! GX4128
« Reply #10 on: 21:43, 27 April 12 »
@ TFM/FS Thanks very much!  :D
Proud owner of 464 GTM64 6128 GTM65, GX4128 and a 464/6128 Plus Hybrid a 20 year long ambition realised! :-)

Offline TFM

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Re: A CPC is Born! GX4128
« Reply #11 on: 22:43, 27 April 12 »
No, no, thank you very much for sharing. I know how incredible much work it is to come that far. And you made it. You really can be proud  :)
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Offline MacDeath

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Re: A CPC is Born! GX4128
« Reply #12 on: 02:07, 28 April 12 »


yeay...
Atari was screwed with this one because it looks terrible, and those Atari 8bit consoles were shitty anyway.
Atari was only good for Atari ST/STE/Falcon/MEgaSTE/TT...
and the Atari Lynx.

(Also the Portofolio...)

The idea of a lower-config computer of the range released as a console was discarded because Atari shat their whole 8bit range...

But clearly, Alan sugar could have gone better as it would then remove the 464 from the range.

Also having a tapedriver plug on the console would also have been a cheap way to enable proper "savegames" possibilities.
it's not like nobody have a tape recorder in 1990...


anyway, to re-use a CPC6128 keyboard is the clever choice to make.
more compact and also the same as the PLUS range...
Perhaps you can even make a proper casing for it with a good cable.
« Last Edit: 02:12, 28 April 12 by MacDeath »

Online robcfg

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Offline Badstarr

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Re: A CPC is Born! GX4128
« Reply #14 on: 20:27, 28 April 12 »
@MacDeath, I do intend to make a nice case for the 6128 keyboard, however, I may still repair the 464 one as it has a retro charm I quite like, on the other hand, the old "If it aint broke don't fix it" philosophy may prevail, as it's working and once I repair the 6128 I could house it in the sawn off 464 case I have with an HxC for a nice compact machine.


@Robcfg, those vids do look nice, much better than I have come to expect from those machines! I guess it's usually the case that many machines only start to really be fully exploited long after obsolescence has set in. That's why a good community like this one is good news for many 8 bit machines that tend to get scoffed at based on the quality (usually the graphics!) of their contemporary software and games. My opinion is that hardware development has always been two steps ahead of software so the machines get left behind by faster machines with more RAM that can be coded for less efficiently and still maintain a reasonable user experience. That's not to say coders aren't talented, it's just that the more space and cpu cycles available the less you have to keep an eye on how much resources are being used up. And that to an extent is the point of having more powerful machines. A good example of how it can all go so badly wrong though would be the horror that was Windows Vista!


So I say "Long Live The 8 Bits!" as they show us that with clever and efficient programming miracles can be achieved!
Proud owner of 464 GTM64 6128 GTM65, GX4128 and a 464/6128 Plus Hybrid a 20 year long ambition realised! :-)

Offline Bryce

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Re: A CPC is Born! GX4128
« Reply #15 on: 11:26, 29 April 12 »
I'm also a big Atari XL/XE fan and from a hardware point of view, they have a few advantages over the CPC.

Bryce.

Offline MacDeath

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Re: A CPC is Born! GX4128
« Reply #16 on: 23:49, 29 April 12 »
Quote
Hmmmm, not as shitty as you think...
yeay I know...

I spend a lot of time at a french forum :
Gamopat.forum...
LA MICRO-INFORMATIQUE 8-16bits HYPOCONDRIAQUE

There are a few Atari 8bit fans there...

But my point was that this Atari 8 bit took like 25years for coders to understand how to do better than a mode0 in 4 colours... sort of.

Its video modes are somewhat quite hard to even understand : complicated...

That's what I like with the CPC... limited video modes, yet simple so efficiants... no attributes nor big constraints.
Just... limited number of colours yet good resolution to compensate, and still a few effects too.


IMO the Atari 8 bit also suffer the MSX syndrome...
"Many" different generations all named the same.
Gotta specify what model you talk about actually...
(which you did Bryce...)

Many guys tell me "MSX is great"...
while they should say "MSX2 or later"... because MSX1 is not that awesome IMO.


but hey, Tramiel killed the Atari 8 bit ranges... because of Atari ST of course.



Yomps on "Atari8bit"...
I guess this could be done almost the same but in mode1 on an amstrad PLUS perhaps...

The Space Harrier is nice, yet somewhat not that much coloured...
It is a modern homebrew though...
I also believe we could get somethoing better on a CPC6128/PLUS cartridge...

Space Harrier on CPC wasn't that good (to much transparency, yet it is fast and almost playable provided you manage to see the things on the screen. But not that much faithfull to Arcade concerning Gameplay (some sort or erzatz...)
 and the second opus was speccy ported too much too, IMO.

Crowland is nice indeed...
I just hope the flickering sprites are due to the emulation...
Nice parallax too, not sure it could be achieved that well on a CPC, but clearly a PLUS can do something looking as good and even playing as well.


Oh, Pokey was a nice soundchip though...
And we al know those britons never put Hardware sprites on their machine which is quite a shame...
« Last Edit: 00:01, 30 April 12 by MacDeath »

Offline MacDeath

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Re: A CPC is Born! GX4128
« Reply #17 on: 00:32, 30 April 12 »
Quote
My opinion is that hardware development has always been two steps ahead of software so the machines get left behind by faster machines with more RAM that can be coded for less efficiently and still maintain a reasonable user experience.
Well...

Software dev was mined by piracy, while Hardware production/dev wasn't.

Also Software makers were limited by their knowledge, experience and imagination... and they were mostly alone...
Many of the best productions were from teams... like a pair of coders, often... (Oliver Twins ?)

At those times, a coder wouldn't share his coding secrets... because doing so he was arming the concurrents.

Proper complete documentation on the electronics parts weren't that complete nor easily available... custom chips in computer were some sort of "secret" that you wouldn't give to rival computer maker... and many tricks (or "undocumented features) were simply by-products of faulty (or genius) designs, not even imaginated by the creators.

ex :
Overscan/full screen on CPC is not really an "official" feature... yet a good surprise...


internet wasn't what it is, coders simply couldn't see each other that easily from one side of the glode to another, or even one part of a country to one other...


In France we had this magazine : Amstrad 100pour100...
it used to have nice technical articles from demomakers (and actually crackers) concerning Overscan, Rasters, scrollingsand so on...

But those were released a bit late in the CPC era... like 1989+... not 1985...


And last but not least... many coders actually still had some habitudes froms older machines...
Many guys who did CPC games were more Speccy coders than actually CPC coders.


Hardware often had one complete year to be developped... while Software had a few months at best.


and so on and so on.

Considering Alan Sugar did a lot of executive medlings, it is a miracle the CPC managed to be a good computer after all.
« Last Edit: 00:39, 30 April 12 by MacDeath »

Offline ukmarkh

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Re: A CPC is Born! GX4128
« Reply #18 on: 01:41, 30 April 12 »
Hmmmm, not as shitty as you think...  :P


Space Harrier - Atari 8-Bit XL/XE (Final Release)


Yoomp! - An 8-bit Atari game

I've always had a soft spot for the Atari 800XL - For me it was an amazing little computer.


atari xl/xe game crownland

Offline TotO

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Re: A CPC is Born! GX4128
« Reply #19 on: 10:48, 30 April 12 »
In France we had this magazine : Amstrad 100pour100...
A great magazine.
But, better to write it : Cent Pour Cent (hundred percent) ... 100% CPC and all about CPC.
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Offline TFM

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Re: A CPC is Born! GX4128
« Reply #20 on: 21:20, 30 April 12 »
I'm also a big Atari XL/XE fan and from a hardware point of view, they have a few advantages over the CPC.

Bryce.
Really? Which one could that be, except the 256 colors? (I'm asking seriously, like usual, would appreciate some short comments).
 
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Offline MacDeath

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Re: A CPC is Born! GX4128
« Reply #21 on: 21:48, 30 April 12 »
Quote
Really? Which one could that be, except the 256 colors?
Well, the 256 colours palette, and a few sprites, the soundchip was good to (4 channels instead of only 3...)

the MOS 6502 wasn't set at the usual 1mhz but at 1,7x mhz... which is quite some kind of overclock too.

And the XE had a nice ATARI ST-like look... which is kool too...
Sadly most (all ?) models lacked in-built disc drive.


And the video modes are somewhat axed on large blocky pixels anyway... and a pain in the @$$ to properly use/program...
Also the hardSprites may be quite... not that good looking (big pixels, not alot of colours anyway...)...

Most of the times, games were like some "Mode0.5"... a mode0 with 4 colours (mostly for the background) but a lots of rasters and a few Hardsprites... perhaps like Ghost and goblin on CPC with more rasters...

Managed nice scrolling though, or even some nice "3D"...
would have been really cool to have the CPU overclocked on the CPC too... ;)

check it by yourself...
60 Best Atari 8-bit games - Part 1
60 Atari 8-bit Games - Part 2
60 Best Atari 8-bit Games - Part 3

So having such a big Palette was often rendered useless because of all the limitations in number of colours actually usable without restrictions...
had the CPC had 256 colour palette, it would have passed as the best Graphic capability of the early 80's
(which it actually was anyway with its cubic3 RGB, lol... and only one grey).

There were a lot of "software video modes" possible on the Atari 8 bit, yet not always that easy to actually exploit for games.

But IMO, those Atari 8 bit games can be good to provide ideas on the way to actually well use the PLUS/GX4000 with mode1, rasters and Hardsprites...

Also if only the Atari ST also had a pokey in addition to its YM... would have been awesome.


But sorry to spoil the topic, it was supposed to deal with a far superior machine : the GX4128...

not an Atari Jokes topic...
« Last Edit: 22:34, 30 April 12 by MacDeath »

Offline TFM

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Re: A CPC is Born! GX4128
« Reply #22 on: 00:24, 01 May 12 »
Ok, ok, you can be likely be right in all that things. But not about the CPU, because the 6502 stuff is just a fart compared to the Z80. Our lovely Z80 can address 16 Bits, and that 6509 buggy-boy can only address 256 bytes directly.
Compare Driller or Starglider on c64/atari with the much more superior version on CPC. The power of the Z80! Year baby!  8)
But I like the Atari (and Atari freax) way more that all c64 stuff (pure evil!).
 
 
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Re: A CPC is Born! GX4128
« Reply #23 on: 03:24, 01 May 12 »
the MOS 6502 wasn't set at the usual 1mhz but at 1,7x mhz... which is quite some kind of overclock too.

Actually, the C64 is the only 6502 machine I know that runs at such a slow speed (maybe because it's actually a 6510). The BBC-B 6502 was clocked at 2MHz.

Offline TFM

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Re: A CPC is Born! GX4128
« Reply #24 on: 17:57, 01 May 12 »
Actually, the C64 is the only 6502 machine I know that runs at such a slow speed (maybe because it's actually a 6510). The BBC-B 6502 was clocked at 2MHz.

Well, the c64 had 0.9 MHz. Actually it runs thereby in the KHz region. :P
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