Some questions about the Timex TC2048/TC2068
I have been doing some research about the specs of these 2 machines but I suppose it would be better to ask for advice in the forum since I have never owned any and I am not aware of any possible issues.
They both use the same "ULA" (SCLD) but only the TC2068 has RGB signals on the espansion bus?
The RGB signals are digital or analogue?
Can the TC2048 be hacked to route the RGB signals to a suitable socket?
Does the video output (CVBS) of these machines show the same dot-crawl like on the Spectrum 48K?
What about the compatibility of these machines with the Spectrum software? I read it is fairly high but anyone remembers great/good games or programs not working tainting Timex's reputation?
The TC2068 uses a cartridge to achieve spectrum compatibility making it work like the TC2048?
The expansion bus is similiar to the Spectrum's? Will peripherals work ok?
The keyboard suffers from membrane problems or is it reliable? Are repairs easy or hard and costly?
What is the general opinion about these clones regarding gaming? Definitely worth or so-so?
They both use the same "ULA" (SCLD) but only the TC2068 has RGB signals on the espansion bus?
The RGB signals are digital or analogue?
Can the TC2048 be hacked to route the RGB signals to a suitable socket?
Does the video output (CVBS) of these machines show the same dot-crawl like on the Spectrum 48K?
What about the compatibility of these machines with the Spectrum software? I read it is fairly high but anyone remembers great/good games or programs not working tainting Timex's reputation?
The TC2068 uses a cartridge to achieve spectrum compatibility making it work like the TC2048?
The expansion bus is similiar to the Spectrum's? Will peripherals work ok?
The keyboard suffers from membrane problems or is it reliable? Are repairs easy or hard and costly?
What is the general opinion about these clones regarding gaming? Definitely worth or so-so?
Post edited by Renegade on
Comments
So the TC2048 would be a better choice if gaming was the primary interest.
Nevertheless, I am still wondering if it would be possible to arrange RGB out from the machine.
Yes, if you want to use the software from the computer ZX Spectrum, TC2048 will be the best choice. Unfortunately, this computer is pretty rare, but it is supported in such projects as the ZX Uno and the ZX Next.
The signals R, G, B, BRIGHT, CSYNC, you can get on the PCB of the TC2048 computer. By the way, studying the differences of electrical circuits TC2048 and TC2068 I found another software incompatibility. Computers TS/TC2068 incorrectly display bright black color. The TC2048 computer does not have this error.
I was using TImex 2048 from 1989 to 1991. I had about 400 games and only few of them didn't work.
Sometimes it was a strange behaviour, sometimes a crash. As far as I remember:
Uridium - game is unplayable because player can't control his spaceship.
Arkanoid, Top Gun, Skateboard Construction System - when you start playing it crashes.
There was an article in Polish magazine "Komputer" about fixing few games (including Uridium), so I think that most of not-working games can be fixed.
Timex 2048 & divIDE 57c
Glad to hear that!
Nice to know that too.
Thanks!
Any CVBS output will display that pattern. It's due to PAL color coding on top of the black and white signal.
From what I remember, my TC2048 image was much the same as the SNES or Amiga in that regard.
I used those machines with the same TVs and there was no difference regarding PAL artifacts, black levels, color saturation, etc.
The original version of the game Arkanoid, Abu-Simbel Profanation, Rasputin, etc will not work on ZX Spectrum Issue 3-6. This is due to changes in the ULA. It is quite natural that these games will not work on the TC2048. For these computers, you must use the patched versions of games.
Coming back to TC2048, here were also some compability issues with ZX Spectrum with regards to mods in the Timex ROM, lack of proper /IORQGE line and other polarity of the embedded Kempston joystick interface.
Don't take me wrong, TC2048 is a very nice computer in small case with embedded Kempston interface, CVBS output on board, not bad keyboard, a proper power switch and power-on led. Size wise is is very similar to any "rubber" Speccy.
Unfortunately all these additional video modes were not used often in the software.
I think that "additional video modes were almost never used in the software" is more accurate :)
Timex 2048 & divIDE 57c
Would those differences be sufficient to cause compatibility issues with a very common spectrum peripheral, I mean, joystick interfaces, the programmable type or not?
And if they do, there is no workaround possible?
I mean, back in the day, were people complaining that joystick interfaces didn't work?
Well, I suppose that if the machine already has an integrated kempston interface gamers would not exactly be looking for an external solution, or would they? (5v and autofire issues perhaps?)
But what about cursor, or sinclair interface, joystick adapters?
Are these known to work with the TC2048?
For instance, Protek joystick interfaces with a switch for selecting kempston/cursor/sinclair are known to work (or not)?
http://www.worldofspectrum.org/infoseekid.cgi?id=1000323
Is there some kind of list with information regarding the pheripherals know to work (or not to work) with the Timex TC2048?
There are two answers to your question:
1) These devices will not work together with the TC2048;
2) If you have a soldering iron, tester, and desire, then anything is possible.
In that case, is there a readable, detailed description of the TC2048 expansion bus connectors?
This is the best I can make of it... >:P
The SCLD was made by NCR in the United States. It's not the same as the ULA made by Ferranti. They would be similar products but would have had a different logic fabric underneath. The circuit was based on the spectrum's ula circuit, however, with changes made for the new video modes and for interfacing the additional hw the machines had.
All Timex ports are fully decoded. So that means things like port 0xfe, which on the spectrum responds to all even ports, only respond to port 0xfe on Timex machines. That's theoretically a compatibility issue but in reality no sw used anything but port 0xfe to access that port. Port 0xff controls the video mode. Some sw on the spectrum read from that port to see ula attribute bytes on the floating bus, an example being Arkanoid. That will not work on Timex machines because port 0xff is a real port on those machines.
Timex made the ts2068's expansion bus compatible with the zx81/ts1000/ts1500 so they could offer peripherals that worked on all machines. The tc2068 changed the ts2068 somewhat by removing some of its bankswitching features. I'm not sure why they did that - perhaps the people doing it (in Portugal) didn't understand or have information about the bankswitching. And of course the ts2068 was a 60Hz machine whereas the tc2068/tc2048 were 50Hz machines so the ts2068 will sometimes run sw faster and there can be more flicker present in some games.
The tc2048 was made to be more compatible with the spectrum by changing the expansion bus to be compatible with the 48k spectrum and they went back to resistor decoupling between the scld and the z80 cpu to recover floating bus behaviour (this is something that causes a lot of rf noise and was designed out of the ts2068 to allow the computer to be sold in the US). They replaced the ts2068 rom with a spectrum rom and put a kempston joystick in (the ts2068 has two joysticks read through the ay chip). Aside from the small gains in compatibility this gets you, the machines are nominally the same if you ignore the extra hardware on the ts/tc2068. The ts2068 cartridge spectrum emulator is nothing more than a spectrum rom in the bottom 16k.
The ts2068 technical manual has a lot of detailed information including a circuit to generate the sync signals for rgb.
https://github.com/z88dk/techdocs/tree/master/targets/timex
Write games in C using Z88DK and SP1
Everything you wrote is irrelevant. The problem is in computer architecture, namely the presence of a bidirectional buffer instead of resistors between the data bus ULA and CPU.
So I have this programmable joystick interface I would like to use with the TC2048, and for which I have the schematic:
It works fine with the spectrum, but could I expect it to work with the TC2048?
I see there D0, D1, D2, D3, D4, A8, A9, A10, A11, A12, A13, A14, A15, +5V, Ground, A0, RD and IOREQ.
According to the chart Claudius posted above the signals are all on the same place of the edge connector in the TC2048, right?
The bad news: the device will not work with TC2048 for the reason I mentioned above. The good news: connecting this device to the TC2048 will not lead to fatal consequences.
Without the intervention of using a soldering iron, only an integrated Kempston Joystick interface.
Without the intervention of using a soldering iron, only an integrated Kempston Joystick interface.
@Black_Cat: Can you propose a modification that would work or know of some modification that succesfully works?
Nothing is impossible. It all depends on whether you are ready to make the necessary changes to the TC2048 computer and the joystick interface.
Of course I would have to assess the level of changes vs my own skills.
But if the work necessary is proven to deliver results then I am sure it would be worth.
You'll be the first one to do this work and you will have to rely on my instructions, and exactly to fulfill them.
Sorry, but that doesn't sound to me the best approach for the situation.
Would you be so kind to share with the rest of the community the alterations you have in mind?
Have you yourself tried any of them on your machine(s) previously?
And what will it change? Maybe someone from the community will be able to do your work for you? I have another suggestion. I'll give one simple task, and if you deem it too complicated for you, then let's stop at this. The first task: open TC2048 and make high-quality photos of the PCB from both sides. It is necessary to know what changes have already been settled.