Author Topic: Joyce hardware  (Read 6529 times)

0 Members and 1 Guest are viewing this topic.

Offline MaV

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.097
  • Country: at
  • Ius summum saepe summa est malitia.
  • Liked: 388
  • Likes Given: 822
Joyce hardware
« on: 01:18, 07 April 11 »
Hi guys!

I bought a Joyce on Ebay a couple of years ago which sadly hasn't seen much use. Primary reasons for this are the monitor and the keyboard.

Comparing Joyce's keys with those of the CPC6128, my guess is, they should be equally easy to handle. But the keyboard that came with mine won't let me type easily, and some keys frequently get stuck. Having it opened and looking at the membrane and the keys I can find no apparent reason for this.

SO:

1) I've decided not investigating any further into the keyboard problem, instead I'll try to find a different solution: Connecting a PC-Keyboard to the Joyce, like Bryce's solution for the CPCs in the wiki.

2) Then there's the floppies which I might be able to replace with an HxC floppy emulator.

3) And lastly, I'd like to get rid of the crt. That means taking out the board, placing it in a new case and trying to find a way to connect it to any other type of lcd monitor/tv. My reasons hopefully are obvious. The crt may have been ok in its day and age, but 50 Hz flickering and monitor radiation just won't do it nowadays.

I'm starting at zero here and do not expect an easy success. It's also not top priority on my list (that'll be a CP/M system built from scratch), but I'd be happy if anyone is able to share info about the three topics.

On a sidenote: I prefer the real hardware to emulation, whenever possible, even if it is cut down to a board. And no, it won't look like a Joyce anymore, but it will still exactly behave like one (hopefully that is).

MaV
Black Mesa Transit Announcement System:
"Work safe, work smart. Your future depends on it."

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.250
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3949
  • Likes Given: 416
Re: Joyce hardware
« Reply #1 on: 10:29, 07 April 11 »
I made a Keyboard Adapter for the CPC?? Shit, I need to cut down on the whisky, I have no recollection of that one. Was it good? :D

On a more serious note:

1) Keyboard: The connector uses a pinout and signals very similar to PS/2 (5V, 0V, Clock and Data) and the protocol was also similar, but I've never tried connecting a PS/2 keyboard to PCW. chances are, amstrad skimped on the handshaking, so a real PS/2 keyboard probably wouldn't initialise. Technically, it wouldn't harm either the PS/2 keyboard or the PCW if you connected them together (assuming you connected the correct pins through an adapter). Worth a try perhaps.

2) Connecting a HxC should be no problem, you'll just have to make an adapter cable.

3) Monitor: Again Amstrad avoided using a standard protocol, so the output of the mainboard is actually a 4 pin connection with NSync, Video and two grounds. Which were the signals required by the LA1385 (CRT driver used in the monitor). The good news is, with a cheap OPAmp and a few resistors and capacitors, you could merge these two signals and the output would be approximately Composite Video (or at least good enough to drive a composite video input). Probably still greyscale, no idea whether Amstrad had any colour information in the signal at all.

Eitherway, I don't own (or intend owning) a PCW, so I can't try any of these things out.

Bryce.
« Last Edit: 11:20, 07 April 11 by Bryce »

Offline arnoldemu

  • Supporter
  • 6128 Plus
  • *
  • Posts: 5.335
  • Country: gb
    • Unofficial Amstrad WWW Resource
  • Liked: 2261
  • Likes Given: 3478
Re: Joyce hardware
« Reply #2 on: 11:40, 07 April 11 »
I made a Keyboard Adapter for the CPC?? Shit, I need to cut down on the whisky, I have no recollection of that one. Was it good? :D
Both were good, the whiskey and the keyboard:

PC USB keyboard on the cpc, all extra windows keys supported, cpc on tft monitor and software loading of sata hd too.
it was great.
My games. My Games
My website with coding examples: Unofficial Amstrad WWW Resource

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.250
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3949
  • Likes Given: 416
Re: Joyce hardware
« Reply #3 on: 12:11, 07 April 11 »
And then the alarm clock rang, and once again, I was back in reality...

(Although my CPC really is connected to a 19" VGA TFT display)

Bryce.

Offline redbox

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.751
  • Country: gb
    • redbox
  • Liked: 326
  • Likes Given: 267
Re: Joyce hardware
« Reply #4 on: 13:36, 07 April 11 »
(Although my CPC really is connected to a 19" VGA TFT display)


And very soon mine will be connected to a 32" LCD TV  ;)

Offline robcfg

  • Supporter
  • 6128 Plus
  • *
  • Posts: 2.266
  • Country: se
  • 8-Bit Technomancer
    • index.php?action=treasury
  • Liked: 1009
  • Likes Given: 2363
Re: Joyce hardware
« Reply #5 on: 13:51, 07 April 11 »
Bite the dust! CPC464 on a 52" Plasma screen  :P



Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.250
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3949
  • Likes Given: 416
Re: Joyce hardware
« Reply #6 on: 14:11, 07 April 11 »
Did you have to meditate to get it to work, or is that picture on the right unrelated? :D

Bryce.

Offline Devilmarkus

  • Vivid source of indefiniteness
  • 6128 Plus
  • ******
  • Posts: 4.035
  • Country: de
  • WebCPC / JavaCPC developer
    • index.php?action=treasury
    • CPC-Live website
  • Liked: 1014
  • Likes Given: 926
Re: Joyce hardware
« Reply #7 on: 15:05, 07 April 11 »
Bite the dust! CPC464 on a 52" Plasma screen  :P




Cool: Lego Duplo for experts ;)
When you put your ear on a hot stove, you can smell how stupid you are ...

Amstrad CPC games in your webbrowser

JavaCPC Desktop Full Release

Offline MaV

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.097
  • Country: at
  • Ius summum saepe summa est malitia.
  • Liked: 388
  • Likes Given: 822
Re: Joyce hardware
« Reply #8 on: 15:16, 07 April 11 »
I made a Keyboard Adapter for the CPC?? Shit, I need to cut down on the whisky, I have no recollection of that one. Was it good? :D
For health reasons I advise you to send me all remaining bottles of whisky. I'll see to it that they'll receive proper treatment.  ;) Boy, I love helping people!  :P

Actually, I've been thinking about the mouse adapter on the wiki page, and you've been one of many contributing to it. Ugh!

Quote
3) Monitor: Again Amstrad avoided using a standard protocol, so the output of the mainboard is actually a 4 pin connection with NSync, Video and two grounds. Which were the signals required by the LA1385 (CRT driver used in the monitor). The good news is, with a cheap OPAmp and a few resistors and capacitors, you could merge these two signals and the output would be approximately Composite Video (or at least good enough to drive a composite video input). Probably still greyscale, no idea whether Amstrad had any colour information in the signal at all.
Ah, good. Or not so good. I'll need to learn more about analog electronics to get the hang of OpAmps.

MaV
Black Mesa Transit Announcement System:
"Work safe, work smart. Your future depends on it."

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.250
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3949
  • Likes Given: 416
Re: Joyce hardware
« Reply #9 on: 15:25, 07 April 11 »
Ok, the PS/2 and USB Mouse adapters are my designs, I'll admit that one :) Can I keep my whisky now? :D

I was about to scribble down a schematic for the OPAmp solution, then I realised that one already exists: http://www.retroisle.com/amstrad/pcw/Technical/Hardware/pcwrfout.php

Ignore the Powersupply part of the schematic and forget the modulator box too, the signal coming out at the top of the 2K2 resistor (just before the modulator) should be close enough to keep most Composite video displays happy.

Disclaimer: I haven't tested this, so measure the signal carefully before you attach it to anything expensive.

Bryce.


Offline MaV

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.097
  • Country: at
  • Ius summum saepe summa est malitia.
  • Liked: 388
  • Likes Given: 822
Re: Joyce hardware
« Reply #10 on: 21:45, 07 April 11 »
Ok, the PS/2 and USB Mouse adapters are my designs, I'll admit that one :) Can I keep my whisky now? :D
In this case, yes you can keep it. But beware of the pink elephant, this species is dangerous and so far only one person in known history has succeded in making money from such a creature. ;)

Quote
I was about to scribble down a schematic for the OPAmp solution, then I realised that one already exists: http://www.retroisle.com/amstrad/pcw/Technical/Hardware/pcwrfout.php

Ignore the Powersupply part of the schematic and forget the modulator box too, the signal coming out at the top of the 2K2 resistor (just before the modulator) should be close enough to keep most Composite video displays happy.

Hey, excellent. There are still a few questions, though:
What's the pulse shaper supposed to do? improve the signal?
What does RVx mean? regulated voltage, I guess. The rectangles are trim potentiometers, right?
What is TPx? test point?
"Supply decoupling" in the right box?

What do the OpAmps exactly do?

I am certain these questions are obvious to an electronics engineer (which I'm not.)

Quote
Disclaimer: I haven't tested this, so measure the signal carefully before you attach it to anything expensive.

Will do.

MaV
Black Mesa Transit Announcement System:
"Work safe, work smart. Your future depends on it."

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.250
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3949
  • Likes Given: 416
Re: Joyce hardware
« Reply #11 on: 22:42, 07 April 11 »
RVx just means Resistor Variable x (ie: they're Potentiometers) with the values written beside them (all 10K) I think he just gave them a reference label so that you know which one to tweak for each voltage level (shown in box at the side). TPx are the test points referenced in the same box. Before you connect the output to a TV, you would need to test each of the three points and vary the resistor until the voltage was correct (ideally you'll need access to an oscilloscope for this). When each point is measuring the correct signal voltage the output levels are correct (and won't damage the TV).

Supply decoupling is the method used to ensure each IC is getting a clean supply (with no noise or ripples). Usually each IC gets a small capacitor across it's power pins. These aren't always shown on the schematic, especially with OPAmps, where the power pins aren't usually shown at all. In this case, he recommends putting a 0.1µf (100nf) capacitor across the three power inputs (two in your case, because one was for the modulator, which you won't have).

The OPAmps in this circuit are just amplifying each signal to the correct level. Each signal (NSync and Video) is first being amplified separately (IC1A/B), to get the signals correct relative to one another, then they are mixed together and the third OPAmp amplifies the mixed signal to the correct level.

Bryce.

Falls du es besser auf Deutsch verstehen würdest, sag mir bescheid und ich erkläre's dir in einem PM.

Offline MaV

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.097
  • Country: at
  • Ius summum saepe summa est malitia.
  • Liked: 388
  • Likes Given: 822
Re: Joyce hardware
« Reply #12 on: 23:48, 07 April 11 »
Supply decoupling ...
Duh! I feel stupid now. It's not as if I haven't already used such capacitors a couple of times (Glättungskondensator). The values and their position - 100nF and not in the schematic but in the key section - should have been enough hints.

Quote
-snip-
Ok, got it.

Still, what's the pulse shaper supposed to do here?

There's also something that looks like a capacitor between TP3 and the 2k2 pull-down resistor. It has no value attached to it, could be denoting a longer distance.

Quote
Falls du es besser auf Deutsch verstehen würdest, sag mir bescheid und ich erkläre's dir in einem PM.
Thanks, Bryce. Everything's crystal clear now. I'm used to reading technical docs in english, so no problem here. Schematics sometimes pose a problem. There's a lot of ways to draw electronics. It's obvious to an expert, not so much to the layman.

Dein Deutsch ist übrigens perfekt. :)

MaV
Black Mesa Transit Announcement System:
"Work safe, work smart. Your future depends on it."

Offline Bryce

  • The Hardware Guy.
  • Supporter
  • 6128 Plus
  • *
  • Posts: 11.250
  • Country: wf
  • It's not broken, it just hasn't been fixed yet.
    • index.php?action=treasury
  • Liked: 3949
  • Likes Given: 416
Re: Joyce hardware
« Reply #13 on: 09:41, 08 April 11 »
Hi MaV,
      The pulse shaper is just two inverters in series for each signal. All this does is clean up the incoming signal, which should be a nice crisp square wave, but most likely isn't, due to lots of different factors. The inverters take a wobbly sloping signal and convert it back to the desired shape (see badly drawn example below) :)

The capacitor at TP3, yes it's a capacitor and yes they forgot to put a value on it, I would choose a 220µf electrolytic here, with the + pole towards the OPAmp. It's there to filter out the DC component of the signal, which may have been introduced from the amplification. It may not be necessary though and the circuit would work without it. Including it might however improve the picture sharpness.

Bryce.


Offline MaV

  • Supporter
  • 6128 Plus
  • *
  • Posts: 1.097
  • Country: at
  • Ius summum saepe summa est malitia.
  • Liked: 388
  • Likes Given: 822
Re: Joyce hardware
« Reply #14 on: 01:47, 10 April 11 »
      The pulse shaper is just two inverters in series for each signal. All this does is clean up the incoming signal, which should be a nice crisp square wave, but most likely isn't, due to lots of different factors. The inverters take a wobbly sloping signal and convert it back to the desired shape (see badly drawn example below) :)
I had a hunch that it must be something like this. The setup itself (two nands) doesn't do anything besides inverting the signal twice.


Quote
Including it might however improve the picture sharpness.

Super! Thanks for your help! I just need to buy the ICs now.

MaV
Black Mesa Transit Announcement System:
"Work safe, work smart. Your future depends on it."