Newbie Timex Sinclair 1000 Questions

[DistantStar001]

Hi all, new to this forum, but figured that I'd jump in with some questions.

I recently got two Timex Sinclair 1000s, and have a few questions.

First, What are the appropriate power supply specifications? I was able to determine that it was 9v and center positive, but I'm not clear on the amps. I've been using the supply from an Atari 2600 and it works, but I've had some bad luck with Commodore 64 PSUs, so the sooner I get the right supply with the right amps the better.

Second, I also got a 16k RAM pack and was wondering how this worked in terms of the memory map? Does the pack add on memory to the existing internal 2k, or does it replace the map altogether (ignores internal, and access 16k in the pack instead)?

Third. Maybe this is more of a software question, but I've tried to load Unkatris (I understand it to be a 1k version of Tetris), both with and without the 16k pack. In both cases, the game does load to the "boot screen" (for lack of a better word). However, without the pack, the game crashes as soon as touch a key, it crashes (grey screen). With the pack, it seems to display something similar to the load screen, only static and not moving. So I have two theories, but both could be wrong, or it could be a combination of the two. Theory one, the game was meant for 50htz, and my TS1000s are 60htz. Theory two, the game was programmed for 1k exclusively. I know that there are some games like that for the VIC-20 that require a certain amount of memory. No more, no less.

I'm also attempting a 16k internal mod to one of these, but I messed up and bridged a trace. I cleaned it up, and resoldered the wires to the board, But I am waiting to get a better socket before I attach them to the SRAM again. Still, I would love to know if I'm on the right track. So pictures below, before I screwup again.

In any case, glad to be here, and any advice or

[1024MAK]

Hello and welcome. You may wish to properly introduce yourself in the welcome area

I’ve moved your thread to the hardware area, as most of your questions are hardware related (you posted in the trading/sales section).

To answer some of your questions:

PSU

Without a memory/RAM pack connected, any DC PSU that can provide 8.5V to 12V (loaded voltage) at 700mA or a higher current is fine. If a regulated DC PSU is used the range is 7.5V to 12V. A PSU with a voltage lower than 9V is often preferred, as this reduces the amount of heat produced inside the computer.

If using with a memory/RAM pack, then a minimum of 10.8V is recommended.

The original Sinclair/Timex PSU are only 9V nominal, because they are unregulated, with no load (nothing connected to the output) their voltage can be as high as 16V. But the output voltage drops under load. At their maximum rated load, the voltage should not drop below 9V.

If using your TS1000 (or ZX81) with power hungry expansions, a PSU with a current rating of 1.2A or greater is recommended. Just a memory expansion / RAM pack on it’s own will run using a 700mA PSU.

External Memory Expansions / RAM Packs
If these have more than 4K bytes of RAM, then they completely disable the internal RAM. All RAM seen by the Z80 CPU will then be provided by the external memory / RAM pack. The start of the RAM is in the exact same place in the memory map. I posted some memory map information here.

I have not tried Unkatris, so can’t answer you question on this game. Most software that will run on an unexpanded machine will run on a machine with 16K bytes of RAM. But some may not. This is due to systems with less than about 4K bytes using a collapsed display file (so save on memory usage).

Keep in mind that the TS1000 and the ZX81 are basically the same machine. Apart from cosmetic and minor differences, the main differences are, the ZX81 has only 1K bytes of internal RAM, The TS1000 has 2K bytes of internal RAM. They use different modulators for the different TV broadcast frequency ranges. Fitting one resistor tells the system to use 60Hz timing for the display. Whereas not fitting this resistor tells the system to use 50Hz timing for the display. BASIC always takes notice of this ‘hardware setting’, but machine code programs may or may not. In any event, the program should not crash. You just may not get a usable display (depending on your TV / monitor).

Internal Memory Upgrade
To upgrade to 16Kbytes, have a read of the links in this post

Mark

[bola_dor]

Third. Maybe this is more of a software question, but I've tried to load Unkatris (I understand it to be a 1k version of Tetris), both with and without the 16k pack. In both cases, the game does load to the "boot screen" (for lack of a better word). However, without the pack, the game crashes as soon as touch a key, it crashes (grey screen). With the pack, it seems to display something similar to the load screen, only static and not moving. So I have two theories, but both could be wrong, or it could be a combination of the two. Theory one, the game was meant for 50htz, and my TS1000s are 60htz. Theory two, the game was programmed for 1k exclusively. I know that there are some games like that for the VIC-20 that require a certain amount of memory. No more, no less.

I felt curious as I have a CZ1000 that is no more nor less than a rebranded TS1000 (not even a clone) but at 50Hz so I googled it

tested it on Eighty One the emulator and it works ok with 2k but not if you enable the 60Hz option..
As you described it has a Loader, not a common thing on this machines.

here are the sources https://sourceforge.net/p/emuscriptoria ... ee/tetris/ it was written in C ...there are the sources perhaps someone can adapt the loader to 60 Hz

UNKTRIS means ONEKTRIS in Spanish BTW...
enjoy your zeddy !!!!

[DistantStar001]

Hi everyone!

First of all thanks to Mark for getting back to me so quickly. Sorry, it's taken me so long to get back to this, but between (now online) school and "quarantine", I've been a little swamped lately.

Second, I followed the instructions for the 16k upgrade as best as I could, but so far, no luck. The best I've gotten is jail bars, then nothing.

This is what it looks like now, but I'm sure I've gotten something wrong here. In any case, everyone can now see my terrible soldering (honestly this is the best work I've done, the rest I'm simply too embarrassed to show).

Third is an additional update that seems to fall within the same theme as my initial post: I recently got an American version ZX81. It was advertised as semi-functional, but have discovered that to be something of an overstatement. But it did come with a few interesting things.

The first was a couple of 16k RAM packs, the wider of which seems to have a dip-switch config and has a pass-through connection on the back? Not sure what that's about.

the other is a bare expansion board with sockets for four ICs and a button in the front, as well as a battery backup on the backside. Any Idea what this is? what it does? and what I need to get it to work?

As for the ZX81, it's been modded with a composite that doesn't output any picture and a reset button that I have no idea if it works because the best I'm getting out of RF is a black screen and occasional wavy bars. Also, there was an IC that was glued upside-down to the board next to the outer ram chip? An SN7400N if that makes any sense to anyone out there. For the life of me, I can't imagine why it was there, or what it was doing (if anything). I removed it on the off chance it was causing a short, but have held on to it just in case. Here's a picture of the underside of the board:

It's a little hard to get one of the oversides given the shortness of the wires from the modifications holding it to the upper case, but you can clearly see the nonfunctional composite mod. Any ideas on how to get this one working would be appreciated as well.

In any case, any help or advice is greatly appreciated, and hopefully, it won't take me forever to get back to all of you.

[1024MAK]

I’ll have a look at your pictures later. However some photos showing the RAM chip from an angle would be helpful, as it is difficult to see the wiring and connections from that single overhead photo.

The Memotech RAM pack has DIP switches so that it can be configured to work with another RAM pack. Hence your ZX81 or TS1000 can then have even more RAM. The other RAM pack is a Sinclair design. If the DIP switches are set correctly, the Sinclair RAM pack can be plugged into the rear of the Memotech RAM pack and that should provide a total of 32K bytes of RAM (assuming both RAM packs are in working order).

The instructions are available on this web site.

The bare board is a Hunter RAM board. IIRC it’s designed to take static RAM (SRAM) chips. If a battery is used, this will retain the data in this type of RAM chip when the mains power is off / disconnected. I don’t have one of these boards, and have not played with one, so I defer to others on this subject. If you search the forum for Hunter you may find out more...

From just the photo of the underside, it’s not possible to help you with your new ZX81 really.
It looks like it has two 2114 RAM chips providing 1K bytes of RAM. I don’t know what the SN7400N (which is four x two input NAND gates) was doing. We would need to see how it was wired in order to work it out.

Mark

[Moggy]

Just to add to Marks comments re the Hunter board.

Made in America by Paul Hunter they can be used in a few configurations.

1) battery backed static RAM board which this one is set up for (the reset switch being the give away)
The push button switch shown here incidently should be on the reverse of the board and a sliding or toggle type write protect switch should occupy this position.

2) It can also be used as an EPROM board using either 4X 2716 EPROMS or 2X 2732 EPROMS made possible by altering a switchable link on the board or 2X static RAM chips and 2X 2716 EPROMS.

I have both types of board c/w manual and some correspondence from Paul hunter to the original US. purchaser.
A scan of the manual I'm sure is posted somewhere on the forum,if not will endeavour to repost if interested.

EDIT.

The manual can be found here..

https://www.sinclairzxworld.com/viewtop ... &start=150

They are very well made and highly prized at the time.

[DistantStar001]

Hello again,

So to begin with here are the angled pics of the TS-1000 mod:

Hopfully they help.

Second, I desoldered the reset switch on the ZX81 to get a picture of the top of the board. In it, you can see where that IC was glued to the board. Like I said it wasn't wired to anything, just glued to the board with its pins sticking in the air?

Also, thank Moggy for the pick of your board. Now not only do I know what parts I need, but also how to reconfigure if I want to. I think I'll stick with the RAM expansion for now since I don't have an ePROM programmer. But it's nice to know I have an option. I guess my only other question is since this board is also a pass-through (line the Memopak) can it too be used in conjunction with the other packs I have? Or is that just overkill?

[Moggy]

Yes ,as Mark says,you can put that Sinclair pack behind the Memotech to get 32k although I find these two packs when used together need a fair bit of power and the standard 700ma power brick can get very hot after prolonged use, so better to use something about 1.5a if possible.

The way I used the board back then was to plug the Hunter board into the 81 then put the Sinclair pack behind it, load say a utility or what ever and save that to the board for future use which was handy in the days of tape loading but this has now been put to bed for me at least with the arrival of the ZXpand and also the battery life of 10 years as stated in the manual was a tad optimistic as I barely managed a year with mine.

[DistantStar001]

Thanks, Moggy! Good to know.

Also, Update! I know the problem with the ZX81! It had a bad ULA. I swapped it the one from the TS-1000 that I still haven't figured out the memory upgrade yet, and it worked! Now I have two working computers instead of just one. I still need to source a new ULA but at least for the moment, PROGRESS!!!

[Moggy]

Two more back on the road, excellent news.