New Hardware Projects

[RWAP]

If we were to design / build some new hardware - what would people be most interested in?

I should think the best bet would be
a) An easy means of getting a stable picture on a colour TV - crisp black on white. I know the later ULA cured this, but most ULAs are soldered to the boards and not easy to replace! Surely something could be done to the signal coming from the UHF modulator?
b) A compact flash / SD card interface to load games immediately - similar to what the DivIDE and DivIDE Plus have done for the Spectrum

[iturbez]

I think both of them are very interesting. And would build both of them...

Go on!

[Mike3]

count me in for both.. hopefully in kit form and not Surface mount....On the video maybe composite & VGA out ... as here in the US we have switched to digital and probably composite may go away also sooner or later...

Mike

[sirmorris]

My SD board is coming soon.

http://arduinonut.blogspot.com/2010/02/ ... -cold.html

It'll be professionally made and can be provided in complete kit form or with smt components already in place, or prebuilt. RAM on board too, but it can be disabled with a jumper if not required because of a pre-existing expansion. I already have most of the software - the most time consuming part of it all - already written.

I admit the DMA side of things might not be working out at the moment but I might just forget about that bit of it all and go back to the original idea of having some ROM on there too.

C

[Mike3]

Looks interresting SIRMORRIS .. count me in for a kit version ....

Mike

[sirmorris]

I'm considering a redesign - this is the right place for a discussion I think

1. Get rid of the microcontroller and revert to my original IO port design - all DIP/TTL for authenticity, ease of building?
2. Add an EPROM with patched LOAD"" routine (and SAVE"" too? is there any use in that?)
3. EPROM disable to use built-in printer/taperoutines.

Possibilities:

Pass-through? If so standard or non-standard? Don't forget the wobble..!
Any good ideas from out there?

I'll be looking to get orders shipped mid April, so when I've got the redesign in hand I can let people know the cost.

Charlie

[RWAP]

Charlie - will you be willing to sell these ready-assembled, in bulk at a discount, so that I could offer them on my website - if people want the kits, then they could purchase direct from you? - I have pm'd you with some discussions.

As for the pass through connector - yes please - but bearing in mind that this will ideally need to sit between the ZX81 and the 16K RAM pack, maybe we should look at another expansion board project, or maybe the one created by littlejohn - viewtopic.php?t=61

The other issue is a keyboard interface - maybe it could be built into the SD/MMC interface to reduce the number of expansions needed?

From memory, the original cost of the expansion board project of $40 was prohibitive - they would have to be half this price to be worthwhile.

The design of the SD/MMC card project would need to take into account whether an expansion board has male or female connectors - perhaps the best solution would be to offer a 3 way expansion board, or just a T expansion board, so the standard 16K plugs in the back and the SD/MMC card in the top.

Anyone else?

[BrunoFlorindo]

Since Rich is a business man, he has to find out if the demand is enough to justify the investment. I honestly have no idea what interests ZX81 users at the moment, worldwide speaking. I really wanted to come up with this AY interface which would be better than the old Zon-X81, in the sense that it would be just like the ZX Spectrum 128K AY, but for the ZX81. Realistically speaking, I think I'm the only one who would enjoy such a thing.

About the Sir Morris's SD card interface, I have to ask: What type of firmware would be used to handle loading and saving? Would it have full FAT32 support?

edit: 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.

[sirmorris]

@Rich
I agree about the keyboard interface - It was something I'd thought of but didn't want to publicly float as you sell replacement keyboards

The RAM will be on-board, with a jumper to disable it if used with a pre-expanded machine. There is enough problem with wobble as it is. I'm wondering if a horizontal board would be better than a vertical. They both have their disadvantages A horizontal form factor would enable a pass-through on the back. I'd still shoot to make a board that would fit into a rampack though

I think this would primarily sell to people that want to chuck something on the back of the machine and not have to worry about expansion backplanes, wobble etc.

@ bruno - I think Yerz might go for that too

[RWAP]

I think that there would be enough interest in an AY interface and also the SD/MC interface - Bruno, you are right, I should set up a web page - I have quite a lot of zx81 customers, so can email them to start with.

The idea of having the RAM built into the SD/MMC interface is good - do we need to ensure it has the hi-res modification?

The main issue will be the firmware - in that something similar to FATware on the ZX Spectrum's DivIDE is ideally required, but also able to write to the card - ie. the user can browse and select a .p file on the SD card (which would be formatted on the PC as FAT) and then load it with LOAD "".

A command would be needed to create a new .p image file on the card and then SAVE "" would save to that image.