Eagle-cad zx-specific parts

[sirmorris]

Hi all,

When I made my IO card I built an edge-connector part that has proved quite useful.

I'll happily give it to anyone that would find a use for it.

Has anyone else put anything like this together?

[BrunoFlorindo]

Hi Sir Morris.
I don't have a use for it at the moment, but pictures or a download link would probably be very useful to hardware hobbyists.
If in a near future we get our own ftp, there could be folders just for hardware, schematics, and projects like the one you mentioned.

[sirmorris]

Gladly.

/me is secretly chuffed that he can offer something

Here is a link to the MMC interface that I built: http://www.robsonfamily.dsl.pipex.com/zxraio.sch

I thought I still had the eagle-cad library that I made for the edge connector but sadly that's gone the way of the dead harddrive. You can hack the rest of the parts from the schematic leaving just the edge connector.

PS I discovered a problem with this design - the IO's A0/A1 lines are attached to A0/A1 on the edge connnector. Which won't work. They should be attached to A8/A9. The IO address decoding scheme of the '81 is funky to say the least. To properly decode the IO the bottom 3 bits must be 1. Which means you can't address the chip's registers. Which if you know about programming the 8255 you'll know what I mean. If you don't know then you'll be glad I told you. But in likelyhood you won't care, so that's fine too If the PIO address lines were on 8/9 then you could use OUT(c),n and put the required address values in B so they get placed on the upper byte of the address lines and passed on to the chip. D'OH!

[sirmorris]

Math123 pointed out that the edge connector part that I use is tailored for my application and doesn't work so well with standard edge connector parts. I'm using header blocks which plug into my edge-connector converter.

So.. I spent my lunch time making a new part - and here it is.

To use this just unzip the 'sinclair.lbr' file into eagle's library folder. Add a new part called 'zx-edge' and you're away!

Please let me know how you get on.

Charlie

[Math123]

Hi Chalie,
got it in my project. Thank you.

Now I wonder how much it will cost to produce the board...
Btw. its a 128 k SRAM with 128k FLASH (both DIL32) and a USB-memorystick-interface with hardware SPI-port made up in an ALTERA EPM7064SLC44. The board fits in a regulad Sinclair 16k Ram housing. Needed 3 signal layers and a ground layer. Hope to get it down to double-layer.
Matthias

[sirmorris]

Nice! I love the 'fits in a rampack' factor

[eduardo]

Hi!

I'm trying to download the Eagle Cad ZX Library posted here, but seens to be no more available (return an error "this file is not available anymore")

Can anyone re-pubublish the file, or, send me this libraries for Eagle CAD?
It will be very usefull in a project that I trying to develop.

Thanks!

[]'s
Eduardo Luccas
Sao Paulo-Brazil

[sirmorris]

Hi Eduardo,

here is the edge connector library. Good luck with your project. Can you say what it is??

Regards

Charlie

[RetroTechie]

Nice! I love the 'fits in a rampack' factor

Considered that for Flash-based mass storage - I wouldn't feel sorry about butchering an original ZX81 RAMpack to bring a ZX81 into the 21st century (well perhaps with RAM pack wobble all over again ). Don't have much use for those RAMpacks anyway since I do ZX81 RAM expansions internally, leaving edge connector free.

The IO address decoding scheme of the '81 is funky to say the least. To properly decode the IO the bottom 3 bits must be 1. Which means you can't address the chip's registers. Which if you know about programming the 8255 you'll know what I mean.

If you're hooking up a 8255 to a ZX81, who says you should use A0/A1 to get consecutive I/O addresses for 8255 A/B/C/control registers? Sure you could use A8/A9 (complicating things programming-wise). You could also use different decode logic, say with 8255 registers on I/O addresses spaced 8 apart. Or use memory-mapped I/O, for example patching that 8255 into 4 non-used addresses in the ROM space (-mirror?). Or some other funky scheme like that.

[eduardo]

Hi Eduardo,
here is the edge connector library. Good luck with your project. Can you say what it is??
Regards
Charlie

Hi Charlie.
First, sorry for long delay to reply.
Thank you very much for the library file.

About my ideia, I have an AY sound interface, from Brasilian Microdigital, for TK85, this interface is compatible with Zon-X. I will re-create the PCB in Eagle, to produce some boards for TK85 enthusiasts, to make possible they can build your own AY interface.


My best regards,

[]'s
Eduardo Luccas
Sao Paulo-Brazil