TS1000 error code 2 keeps happening

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bwinkel67
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Re: TS1000 error code 2 keeps happening

Post by bwinkel67 »

XavSnap wrote: Thu May 28, 2020 11:55 am If it's a Sinclair Ram Pack, may be an ULA error… :oops:
Not the inboard ULA in the Zx81, but in the Ram Pack…
Yup, a TS1000 (Sinclair) RAM pack
XavSnap wrote: Thu May 28, 2020 11:55 am A faulty RAM case up to 2kb... too.
Wasn't quite sure what that meant? Are the RAM chips in the pack 2k chips? I have an opened motherboard TS1000, so could I just grab it's 2K chip and piggyback on each chip for a quick test to find which one it may be?
XavSnap wrote: Thu May 28, 2020 11:55 am 4 caps in the RAM pack: Try to install a 1uf per RAM case, and a global polarisez one to ajust de voltage level.
So replace all 4 caps but make on 1uf?

I'll have to see what a plarizes one is...if I can adjust voltage level would that help with the interference it is giving on the RF feed?
XavSnap wrote: Thu May 28, 2020 11:55 am Some of my RAM pack corrupt the display too… it was a know problem.
The Ram pack calibration was set to another zx81's circuit, some of mine seem to run properly on another Zx81 !
This RAM pack came with my other TS1000 (bought at a yard sale 25 years ago) that I have out of the case (broken keyboard). It will be my hardware project to add composite out since its' RF doesn't provide a backporch signal, making it rather useless when connecting to most LCD and color CRT TV's.
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XavSnap
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Re: TS1000 error code 2 keeps happening

Post by XavSnap »

RamPack.jpg
So replace all 4 caps but make on 1uf?
No, in this case, try to change each capacitor.
If it steel wrong, check the capacitor in the Zx81's case to drive the 7805 regulator.

Yes, you can try the piggyback.

:mrgreen:
But, it seem to be an address decoding problem from the ULA...
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
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1024MAK
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Re: TS1000 error code 2 keeps happening

Post by 1024MAK »

The Sinclair/Timex RAM packs use eight 4116 (or equivalent) one bit x 16K DRAM chips. One physical chip stores one bit of a byte. So to store a whole 8 bit byte, you need eight chips.

There are various versions of the Sinclair/Timex RAM packs, the earlier version uses two circuit boards and multiple multiplexer chips. A partial failure of one of these can cause all kinds of weird failures, as the Z80 and the ROM code doesn’t detect a failure of this type.

Later versions use a single PCB and Sinclair used a ULA to reduce the chip count. Again, a partial failure can cause all kinds of weird failures.

It may or may not help to replace the electrolytic capacitors. Replace with new parts rated at the same or greater voltage, and with the same value (in uF).

I think XavSnap is suggesting fitting additional 470nF or 1uF multilayer ceramic capacitors across pin 8 and pin 16 on the DRAM chips to reduce screen jail bar patterning. This is unlikely to sort out the errors you are getting.

Mark
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bwinkel67
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Re: TS1000 error code 2 keeps happening

Post by bwinkel67 »

I have the dual circuit board variety. It may be a loose solder joint on the connector as the RAM pack works when first used but as it heats up it starts to falter (same with the screen glitch) so I will look to the connector first, and the ribbon connector between the two circuit board as well, to see if I see any dry solder joints and re-heat them.

I will also try the cap technique to get rid of interference once I've figured out what's wrong with the RAM pack.

You can get them for under $20 here in the US on eBay so I'll see how much time I will spend on debugging it...

The demo program below crapped out yesterday after printing two lines and now it ran through three full iterations (choice 3) and on the fourth one finally gave an error (C/140). Yesterday I first ran Elite and killed like 4 pirates before it started giving errors so it does requiring heating up before failure -- i.e. that seems to be consistent). The screen glitch occurred sooner, after going through the square pattern and starting at the spiral one. It's pretty warm today with 83 in my room so that might cause it to act up quickly.

banner.p
(2.03 KiB) Downloaded 237 times

BTW, having finally figured out how to load programs from a wave file makes it much easier to use the TS1000. All I needed was a LCD TV that showed the loading pattern and luckily my cheap SuperSonic TV did. Still can't get programs from and old cassette loaded on EightyOne -- I have one, Battleship, that I wrote as a kid that almost got published by Gladstone right before Timex pulled the plug that I really want to get. The cassette itself looks brand new and has been kept in a dry cool place. Am looking on craigslist for a free cassette recorder so I can try with that. Sampling with audacity was just futile and I even tried to match to the output of wave files that EightyOne generates but those are so clean and digital it's hard to use as a starting point.

One final question, is it easy to upgrade the TS1000 internally to take 16K? Can you just plop in a 16K chip in place of the 2K or is there a limit? If so what chip should I be hunting for. Not having the RAM wobble would be nice plus, and I'm guessing, like the TS1500, you could then extend to 32K if needed.
bwinkel67
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Re: TS1000 error code 2 keeps happening

Post by bwinkel67 »

An observation that doesn't have to do with the malfunction of the RAM pack. When using a RAM pack it seems to speed up some computations and slow down others. So two examples:

This one is slower on 2K TS1000 compared to 16K TS1000 (5.5 seconds vs 3.3 seconds to fill screen):

Code: Select all

10 PRINT "HELLO";
20 GOTO 10

Whereas this one is faster on 2K TS1000 compared to 16K TS1000.

Code: Select all

 5 SCROLL
 10 PRINT "HELLO"
 15 GOTO 5
 

I haven't tested difference between numeric computations like this:

Code: Select all

10 LET I=0
20 LET I=I+1
30 SCROLL
40 PRINT I
50 GOTO 20
But the ZXSimulator, which runs at 9.5 seconds on the above first test compared to 5.5 seconds, will literally run over 4 times faster on this simple increment test. It makes sense since that it's slower printing a screen full of text as my character plotting routines do slow things down a bit. Computationally it currently only does integer arithmetic so that may be why it is faster and I have a plan to keep addition/subtraction as integer when implementing floating point (shifting it 4-5 digits base-10 works) so it should still be close that that speed difference. Just didn't expect over 4 times of a slowdown on TS1000.
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1024MAK
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Re: TS1000 error code 2 keeps happening

Post by 1024MAK »

Alas, an internal RAM upgrade is slightly more complex than just fitting a larger capacity chip. But it’s not difficult. See this post for the relevant links ;-)

Mark
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bwinkel67
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Re: TS1000 error code 2 keeps happening

Post by bwinkel67 »

So taking the RAM pack out of its case seems to have fixed the corruption. That suggests a loose contact/solder-joint. The video glitched about 5 minutes into starting up the computer. I went out and came back half an hour later and it was still running but no video glitch. So perhaps the LCD TV/Monitor (Toshiba) adjusted itself to the video signal. I know on my cheaper one (SuperSonic) it more literally adjusts itself by going into color and then black & white.

I have since loaded Minesweeper and played a game so all seems to be working at the moment. Minesweeper uses the most amount of memory.
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1024MAK
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Re: TS1000 error code 2 keeps happening

Post by 1024MAK »

An unexpanded ZX81 or TS1000 operates with a ‘collapsed screen’ (D_FILE) to keep RAM usage to a minimum.
When there is plenty of spare RAM (e.g. a 16K byte RAM pack is fitted), the screen (D_FILE) is expanded to full size.
The fully expanded screen RAM size is 793 bytes (32x24 + 25 HALTs, almost occupying a whole 1Kbyte of RAM), an empty fully collapsed screen occupies only 25 bytes (HALTs).
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
bwinkel67
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Re: TS1000 error code 2 keeps happening

Post by bwinkel67 »

That makes more sense now in how you can actually write usable 1K programs...never understood that before. Kind of cool that the screen collapses to a minimum.
bwinkel67
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Re: TS1000 error code 2 keeps happening

Post by bwinkel67 »

Woohoo, I was able to finally load Battleship off of my old cassette to the TS1000. I had recorded the entire thing via audacity and had little luck getting EightyOne to read it in. However, playing it back out to the TS1000 did the trick. At least I got screen shots of the 15 or so pages of code I'll get to type in but that's the first real game I wrote as a kid which almost got published as a TS1000 game. I'll post the .p file here once I recreate it.
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