New Hardware Projects

[sirmorris]

The trouble with packing everything onto one board (I know this hasn't yet been suggested, I'm kind-of heading off the idea at the pass ;¬) is that you increase the cost for everyone for the benefit of very few.

I'm just thinking out loud here.

If the SD/MMC (or RAM card or whatever) had an expansion port on it with the IO addresses already decoded etc it would be trivial to add an AY, keyboard, joystick interface I'm sure.

Repeat the mantra - wobble is the enemy - wobble is the enemy.

I've always thought an expansion that sits _under_ the zx would be the best - after a dk' case full-size keyboard mod, that is. A small rectangular unit that the zx sits on top of, screws into the underside of the case, connects via ribbon.

OOh now there's a thought - should that be the way to go? Connect to the expansions via ribbon? They could stack up one-on-top of the other like a cake at the back of the unit. There'd be no wobble and you could add all the bits you wanted.

RAM, card storage, keyboard/joy, AY, voice, nuclear power controller...

Of course - there'd have to be more than 2 people interested to make this all worthwhile..!

[RWAP]

Rich, didn't you had a list somewhere where users could let you know what they were interested in? If it was in this forum, it tends to get forgotten. A page similar to what you did for DivIDE+ orders could probably help. A list of hardware that you know exists for the ZX81 (or existed), plus the option for 'other hardware not listed here') and next to each item the number of people interested in it. These users would send you their name, e-mail address and the item they would happily purchase, but the only thing published would be the number of people interested in each item. The other information would be kept private. Just an idea.

I have created a page about possible projects - see http://www.rwapsoftware.co.uk/zx81/zx81_projects.html

[RWAP]

The trouble with packing everything onto one board (I know this hasn't yet been suggested, I'm kind-of heading off the idea at the pass ;¬) is that you increase the cost for everyone for the benefit of very few.

I'm just thinking out loud here.

If the SD/MMC (or RAM card or whatever) had an expansion port on it with the IO addresses already decoded etc it would be trivial to add an AY, keyboard, joystick interface I'm sure.

Repeat the mantra - wobble is the enemy - wobble is the enemy.

I've always thought an expansion that sits _under_ the zx would be the best - after a dk' case full-size keyboard mod, that is. A small rectangular unit that the zx sits on top of, screws into the underside of the case, connects via ribbon.

OOh now there's a thought - should that be the way to go? Connect to the expansions via ribbon? They could stack up one-on-top of the other like a cake at the back of the unit. There'd be no wobble and you could add all the bits you wanted.

RAM, card storage, keyboard/joy, AY, voice, nuclear power controller...

Of course - there'd have to be more than 2 people interested to make this all worthwhile..!

I agree - individual interfaces are better as they are cheaper to produce and sell.

The problem with an expansion unit underneath the ZX81 is that the angle and height of the keyboard is changed, which will not suit everyone. Ribbon cables are an option, although they look untidy - how about just a means of connecting interfaces together in series (eg. a screw peg at the top which could even be connected to the 16K Ram pack?)

[Moggy]

This is fantastic!!!! could this be a revival of all the little cottage industries that sprang up in the eighties ? the enthusiasm and know how seems to be there. Having whetted My appetite on Hunter memory boards I will happily buy an sd board in fact I will buy anything thats made. The ay interface is interesting providing some useful software accompanies it (My zonx 81 is nothing more than a glossy black brick!!) As for the connection method I seem to remember a company at the time , whose name escapes me, used the ribbon cable and cake stack method Sir Morris describes, very succesfully. They offered a full office suite assembler etc. The cable was short and therefore looked very tidy was very stable but the injection mouldings used would cost a bloody fortune these days !!!!
Full praise to Sir Morris and Rich for time and effort put into this as for who would buy it all can do is mis-quote a line from the film Field of dreams ..." Build it and I will come"!!

11 out of 10 Chaps Moggy


PS Does Anyone else's houselights go dim whenever Sir Morris starts another project!!?

[sirmorris]

PS Does Anyone else's houselights go dim whenever Sir Morris starts another project!!?

ROFL

Thanks for the enthusiasm

I'm getting excited about cake layers now. The plug at the zeddy could carry a couple of extra signals - one in particular would be useful - video - but that would require a clip or solder connection inside the machine.

[siggi]

Hi Charlie,
the German ZX-Team uses a 64 pin VG connector to avoid any wobble. It has some pins free for additional signal (like video). If you would use the same connector, we could easily share the new and existing expansion cards. See Kai's pages for details:

http://www.fischerkai.de/zxteam/zx96_e.htm

For those who prefer wobbeling: it's easy to make some adapters to connect both types of connector:

Adapter_1024x768.JPG

(184.8 KiB) Downloaded 1837 times

And here is my ZX81-Laptop with Kai's AT-Keyboard interface card attached:

AT-KBD_1024x768.JPG

(190.09 KiB) Downloaded 1836 times

Siggi

PS: I am currently thinking about a docking station for my ZX-Laptop: with AT-Keyboard-Interface, Monitor, serial ports, ....

[sirmorris]

Haha that's brilliant

For me the most important thing however is that any casual zx81 user could feel they want to buy one Plug in and play, not be concerned with future expansions. If that was a possibility then great, otherwise it must appear as simple as possible.

We, the 'hardcore' users must have possibilities too. I love the DIN connectors - they're very stable and I would be tempted to solder one directly to the zx81 edge connector. But I don't think that's an option for someone making an impulse buy so they can play monster maze once or twice

Another connector I have my eye on is a 50 pin dual row pin header. Something you could use a SCSI interconnect for. They're as easy to buy as the DIN connectors and you may already have some

[Moggy]

"For me the most important thing however is that any casual zx81 user could feel they want to buy one Plug in and play, not be concerned with future expansions. If that was a possibility then great, otherwise it must appear as simple as possible."

Good points Sir Morris whilst it is great ,for those so inclined, to connect up to their fridge, microvave , transporter pad or phaser array, some of us just want to keep their collection "as is"
and buy either a recreation of old expansions with decent software or newer ideas that did not exist then sd boards etc, built with original connector types wobble not withstanding I thought that was the original premise to make and sell whats viable. The "hardcore" guys would be more happy , I suspect , building rather then buying, not all of us are that technicaly able and like You say some of Us just want to plug and play and do not want to spend half a day pulling levers and tying up bits of string etc but remain , I hope , accepted forum members.

Anyway rant over


Regards Moggy


Build Me a MIDI interface and I will retract everything!!!!!

[BrunoFlorindo]

No one will probably like this idea, but I'll mention it anyway. Instead of ribbon cable, expansion boards and similar things, how come no one has come up with something like this but for the ZX81 and Spectrum?



(original link is now dead)

[siggi]

The pure Z80 inside the ZX81 or Spectrum is not able to drive such a long cable. This would require line drivers and a well-terminated bus to avoid signal distortions.
I made something similar to drive a very long cable to an external keyboard (for buffering of the Z80 address lines, used for keyboard scanning).

Siggi