New ZX80 boards

[zx81jens]

@Lee:

i have (at the moment) four members who have interest - and i think there would be more.

the schematics would be nice. please send it to zx81jens (at) gmx.de

we have linked this post to our german forum right here: http://forum.tlienhard.com/phpBB3/viewt ... 1816#p1816

the ZX80 is a great machine - i have two of them, one with the ZX80-ROM and one with the ZX81-UPGRADE. i also have some ZX81 with a lot of things on it (like USB an Commodore64-Floppy).

many warm and sunny greetings from germany (spring is here) and thank you
jens

[Lee Hart]

1. The question over files... OK, let's see if I can attach a PDF file of the schematic...
Nope; it says "the extension pdf is not allowed." What extensions are allowed?
Or... I did send a copy to zx81jens -- perhaps he will post it somewhere?

2. Copyright infringement... the simplest thing to do would be to approach Sinclair/Amstrad.

> However, you are not making an exact copy of the original - it will be functionally
> the same, but you will have your own circuit board and off the shelf chips - software
> has to undergo a "look and feel" test, but not hardware for copyright infringement.

Correct.

> The only custom chip would be the ROM and ULA - I presume the ZX80 has a ULA?

No, the ZX80 uses only common generic ICs. No ULA; indeed, no custom parts at all. That is what attracted me to it! My ZX80 board is the same.

The ROM code is of course unique. But there are lots of clones of the ZX80 and ZX81 ROMs that can be used that are functionally equivalent but different from the originals.

[BrunoFlorindo]

Hi Lee and welcome aboard.
I'm very active in everything-Sinclair, from the ZX80 and Microace (have both here in the U.S.) to the Spectrum +3 and all Timex computers as well (Portuguese and U.S. versions). I encourage anyone who has an active interest in preserving or developing anything related to these computers. Your project sounds very exciting!
I'll mention a few things that I've heard and read, but the Spectrum people on CSS or WOS are best qualified to clarify these things.
I know for a fact that ZX Spectrum coders are working on something called Open82. It's a project aimed at creating a 100% compatible rom for the ZX Spectrum clones (like the Harlequin, which is still w.i.p.), but free of any Amstrad code. How did they start this project? By using the ZX81 rom as a start. It seems the ZX81 rom has something to do with Nine Tiles software and isn't subject to any restrictions from Amstrad. Now that we're talking about an even older Sinclair machine, I'm inclined to believe it's a similar situation. It would need confirmation, but we should not contact Amstrad. Amstrad has been bought recently by another corporation, and these little hobbyist projects could be interpreted the wrong way. I don't recommend contacting anyone. There are people on CSS and WOS that know the answers to these questions. The nice folks at #spin on irc.coldfront.net can also give a fast reply if you look for them during the day (European time).
But there's an easy way around this, something that doesn't require confirmation from anyone and avoids worries or the possibility of legal complications. The ZX80 board could be sold without any rom, but with an eprom or flash memory that can be programmed with whatever the user wants or already has. We've done this with the Spectrum and it worked. On the Spectrum we do it with RS232 or the Joystick port, but we flash cartridges with it, not the internal rom. But it works! It's also better than buying eprom burners.
Of course, this whole "issue" would only be real if it was a commercial venture. If it's between a group of Sinclair enthusiasts, I don't think there would be any problem.
Please share some pictures of the work you have done. It would be great to see.

[RWAP]

1. The question over files... OK, let's see if I can attach a PDF file of the schematic...
Nope; it says "the extension pdf is not allowed." What extensions are allowed?
Or... I did send a copy to zx81jens -- perhaps he will post it somewhere?

Image files are the ones allowed by the board mainly - although you can email me the pdf and I will store it on my server if you like - send to rich AT rwapservices DOT co DOT uk

[zx81jens]

hi lee, hi guys (and girls, if there were any)

some time ago i was on ebay.it (italy) an found a ZX80/ZX81-clone in one machine (!) - it is called TL801. finally, the website http://www.zx80.it and the producer of the TL801 are no longer there... what a pitty.

i have no schematics from the TL801, but with the kit i ordered an extra board (without the chips). maybe that is usefull to you? i´ll scan this an send it to you directly (maybe this weekend if there is time). i will also link a thread from the german forum, where i´ll show your schematics and the layout

the TL801 has "two" machines on one board: the ZX80 and the ZX81 (without NMI). you have both ROM in one chip an can switch between it by changing a jumper. that works fine.

thank you form your marvellous work
greetings
jens

[BrunoFlorindo]

Before I go to work I thought I should post here an e-mail from Andrew Owen which helps clarify things regarding the ZX80 rom:

Code: Select all

> I know for a fact that ZX Spectrum coders are working on something called Open82.

It's not dead, but it's not healthy. There's still 7K of Amstrad code
in SE Basic and I've given up much hope of ever making that Open
Source.

> How did they start this project? By using the ZX81 rom as a start.

That's a bit misleading. The original OpenZX project (which merged with
Open82) had nothing to do with the ZX81. Open82 brought the ZX81 math
library to the table.

> It seems the ZX81 rom has something to do with Nine Tiles software and isn't subject to any
> restrictions from Amstrad.

The ZX80 ROM is copyright 1980 Nine Tiles Networks Ltd. The ZX81 ROM
is copyright 1981 Nine Tiles Networks Ltd. I contacted John Grant
directly to ask for permission to distribute the ZX81 ROM under the
GPL. There is implied permission to do the same for the ZX80 ROM in
the email I received.

I would recommend that anyone planning on distributing a ZX80 board
contact Nine TIles Networks Ltd directly as a courtesy to John Grant.

Regards

-Andrew

Again, this would only apply if what's being planned had a commercial purpose. If it's only for a few of us and we're just covering the cost of getting the boards done, it should be ok.

[RWAP]

The schematic appears at: http://www.rwapsoftware.co.uk/downloads/zx80sch.pdf

The silk screening for the PCB appears at: http://www.rwapsoftware.co.uk/downloads/zx80silk.pdf

[zx81jens]

hi!

here is the link to the german forum:

http://forum.tlienhard.com/phpBB3/viewt ... 1819#p1819

greetings
jens

[sirmorris]

I am very *very* excited by all of this.

Carry on!

C

[Mike3]

Count me in for a board also....

Mike