List of ULA availability

ZX80 / ZX81 hardware and software offered for sale or swapping
User avatar
1024MAK
Posts: 1779
Joined: Mon Sep 26, 2011 9:56 am
Location: Looking forward to summer in Somerset, UK...

Re: List of ULA availability

Post by 1024MAK » Sat Sep 24, 2016 9:48 pm

Right, I have just checked my own archive, and I have some good news. I have both a copy of Andy's ULA page including pictures and a copy of RetroTechie's web site (http://bitcycle.org/) from 1st August 2015 including the zip file.

If the owners / authors can confirm that they are happy for me to make these available, I will do so.

Mark

User avatar
Andy Rea
Posts: 1267
Joined: Fri May 09, 2008 1:48 pm
Location: notts UK

Re: List of ULA availability

Post by Andy Rea » Sat Sep 24, 2016 10:41 pm

I'm happy for you to make my little bit available to all.

.andy
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

User avatar
RetroTechie
Posts: 325
Joined: Mon Oct 31, 2011 11:16 pm
Location: Hengelo, NL
Contact:

Re: List of ULA availability

Post by RetroTechie » Sun Sep 25, 2016 1:04 am

1024MAK wrote:RetroTechie's web site (http://bitcycle.org/) has been off line for a little while now, but I don't know anything more.
Probably automatic payment for a hosting-related bill went wrong. But so far I haven't bothered to find out what needs doing as I've been busy with more important things. It is/was a pretty low-traffic site, and as said the Internet Archive has most of it for those who care.
The Internet Archive does have a lot of his site here but I don't think it has the zip file to download :-(
Attachments
ZX81_ULA-in-a-CPLD_v1.10.zip
Most recent version at time of this post
(1.78 MiB) Downloaded 106 times
Bitcycle.org - just flipping bits

User avatar
1024MAK
Posts: 1779
Joined: Mon Sep 26, 2011 9:56 am
Location: Looking forward to summer in Somerset, UK...

Re: List of ULA availability

Post by 1024MAK » Sun Sep 25, 2016 1:08 pm

Andy Rea wrote:I'm happy for you to make my little bit available to all.

.andy
Said files attached ;)
ZX81 ULA Replacement ula.zip
(370.93 KiB) Downloaded 138 times
Mark

User avatar
Fwapp
Posts: 147
Joined: Mon Jun 01, 2015 9:32 pm

Re: List of ULA availability

Post by Fwapp » Sun Sep 25, 2016 5:33 pm

Ta :)
ZX80, ZX81 - 2C158C Bugged Rom iss.1, 2C158C "kludge fix" iss1, 2C184E iss1, 2C210E iss3, US NTSC iss1 "straight traces", US NTSC iss3 TS1000

User avatar
PokeMon
Posts: 2142
Joined: Sat Sep 17, 2011 5:48 pm

Re: List of ULA availability

Post by PokeMon » Sun Sep 25, 2016 11:12 pm

Thanks, backed up personally right now. 8-)

User avatar
mrtinb
Posts: 508
Joined: Fri Nov 06, 2015 4:44 pm
Location: Denmark
Contact:

Re: List of ULA availability

Post by mrtinb » Wed Oct 19, 2016 6:50 pm

Martin
ZX81, Lambda 8300, Commodore 64, Mac G4 Cube

gsreis
Posts: 3
Joined: Sun Jul 02, 2017 3:33 pm

Re: List of ULA availability

Post by gsreis » Sun Jul 02, 2017 3:58 pm

There are some time since last post, and my question is how mature is this schematic ?
Is it safe to construct this circuit to replace ULA ? Have someone try to assemble it ?
thank !!!

User avatar
Andy Rea
Posts: 1267
Joined: Fri May 09, 2008 1:48 pm
Location: notts UK

Re: List of ULA availability

Post by Andy Rea » Sun Jul 02, 2017 4:26 pm

whilst this TTL version that i built many years ago worked it was not without some small problems, hsync timing not perfect, no back porch, it was built using parts i already had rather than " ideal" parts.

you would be much better off ( if its a schematic your after ) looking at Mark's great work found here. download/file.php?id=1246
RetroTechie wrote:
Mon Apr 15, 2013 12:05 am
Why didn't I try this before... :idea:
Let's hope the file size isn't an issue for maintainer(s?) of this site - it shouldn't be I think, as this is low-traffic material. :lol:
ZX81_ULA-in-a-CPLD_v1.10.zip
Rink wrote:I wonder what the utilisation of the CPLD is like? I'd be tempted to see if I can put the design in an Altera CPLD since I've been playing with those lately.
My design uses 59 macrocells from a 72 macrocell CPLD (Xilinx XC9572). So with a bit of luck it might fit in a 64 macrocell Altera CPLD. But that would be a tight fit. Unfortunately 128 macrocell Altera devices I know off, come in 100 pin QFP packages. Which is just a little too big to fit onto a 40p-DIP footprint (although Andy somehow managed that anyway :mrgreen: ).

ZX81 ULA logic isn't very complex - a few counters, a few flipflops, an 8 bit shift register, and some logic tying things together. Understanding how everything works together in a ZX81 is the hard part IMHO. A 64 macrocell will probably do if all you need is a 'vanilla' ZX81 ULA replacement. If you want to add extra's like clock doubling/tripling, a blockswitching mechanism for the RAM etc, then better go for a 128 macrocell device.

You'll also need 5V tolerant inputs, and personally I have a strong preference for not starting new designs using parts that are considered obsolete. So for this application I'd be looking at Xilinx 9500XL (XC9572XL in VQ64 package would be a nice choice), or Altera MAX 3000A family.
also please not that Paul is currently working on a cpld based plug in replacment.

regards
6 x ZX81, 1 x TS1500 , 1 x +3e, 1 x timex 2040 printer, 1 x timex 2020 cassette deck, siclair printer and some spectrum

Post Reply

Who is online

Users browsing this forum: No registered users and 2 guests