Sinclair ZX80 / ZX81 / Z88 Forums

I did spot some cheapish CPLDs on eBay.com: EPM7256SQC208-10....$7 each..Can be programmed with USB Blaster + JTAG (I Believe) has 256 Macrocells & 160 I/O lines,but is surface mount ! http://www.ebay.com/itm/Altera-IC-CPLD-256MC-10NS-208QFP-EPM7256SQC208-10-NEW-/182324077815?hash=item2a735ca4f7:g:...

I spotted an interesting Article in PyroElectro (PyroElectro.com) about using a CPLD (EPM7128SLC84) to generate a VGA video output : http://www.pyroelectro.com/tutorials/fpga_vga_resistor_dac/index.html I also spotted the software to program the Altera devices : http://dl.altera.com/?edition=lite Bu...

Which CPLD to choose Xlinix, Altera etc ?

I’ve been looking at Complex Programmable Logic Devices (CPLDs) and wondered which to choose ?? The Altera MAX ones look cheap and the USB Blaster cable is cheap ..But which is best, easiest to program etc ??

I believe DiskonChip was an early form of Flash Memory a sort of precursor to modern flash pens/drives. I suppose with the necessary Glue logic a DiskonChip could be made to function as a Floppy emulator. Though you could do the same with NVSRAM such as DS1250, however, though this is only 512K x 8 ...

Video Circuit TIMEX Sinclair 1500+

Do you have any more details about the Video circuit , using a CPLD + DACs + NTSC encoder + TMS9918 ?? As if you could get this working it would be cool in many other homebrew microcomputers !

Information only (for those that are into building homebrew computer): http://stores.ebay.com/P-A-Electro-Components/DIY-Homebrew-Kits-/_i.html?_fsub=8692137013 I had spotted these kits... the ZX Spectrum one likes quite interesting.. I have bought stuff from them in the past so they are OK, though...

The USB Blasters are pretty Cheap and do work OK.. The EPM9320s from Digikey are £101 each !! I've got several CPLDs that I got Cheap anyhow! EPM7128SLC84 (64 I/O lines, as fast as 7ns, 128 macrocells) would do the Job...but might as well go for something better... can be sourced for as little as $2...

At this stage it's all just ideas in my head..what you may call the design or feasibility stage. But one possible solution could be : Z80 CPU (possibly 20MHz Z84C0020VEC) EPM9320LC84 CPLD 320 macrocells ..I've found a source where I can get these Cheap (£14.50 each) 64K SRAM (possibly UM61512 15ns D...

I remember someone telling me it had been done using GALs and it used less than 128 Macrocells...? though it would be nice to have a few extra Graphics modes and stuff as the original ZX81 was somewhat lacking in these respects. Plus I can get the CPLDs cheap (I already have some) . The CY7C341s are...

Hi. I'm new to the ZX81 forum, but have recently been toying with the idea of making my own Z80 computer (based on ZX81) . I have some CPLDs GALs and stuff (plus Z80 CPUs obviously). My question is : how many Macrocells does the ZX81 ULA take/need as I have some EPM7128s (128 Macrocells),CY7C341-35s...