Oh no! Not another ULA.

Any discussions related to the creation of new hardware or software for the ZX80 or ZX81
Post Reply
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Oh no! Not another ULA.

Post by Andy Rea »

Yes folks you heard it here first... Very much still a work in progress

using real 5v part :mrgreen: nobody wants stinky 3.3v stuff :lol:

Shall we play a game? spot the difference....
Image

Got it yet? On the left we have altera unobtanium, Whilst on the right Atmel still in production...but for how long who knows>

anyway the plan is to produce two versions, price will be cheaper for standard version because chip is cheaper

Enhanced version similar in operation to my old altera design and will include clock doubling also but of course will require those extra wires ( if you know, you know )

the form factor is unusual and may not be for everyone it will fit inside an original case but better use an old beat up one since it requires the removal of the pcb support pillar near the regulator.

Regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
User avatar
Paul
Posts: 1546
Joined: Thu May 27, 2010 8:15 am
Location: Germanys west end

Re: Oh no! Not another ULA.

Post by Paul »

Hi Andy, great that you're making another Version!
Could you please post a picture with an Issue1 and an Issue3 board for mounting reference?
I can't really imagine how it fits inside ;)
Cheers Paul
In theory, there is no difference between theory and practice. But, in practice, there is.
Moggy
Posts: 3333
Joined: Wed Jun 18, 2008 2:00 pm

Re: Oh no! Not another ULA.

Post by Moggy »

Yes folks you heard it here first...


Really? :twisted:
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Oh no! Not another ULA.

Post by Andy Rea »

Hi Paul,

the issue 1 photos are in a socket on the board and is operational, The issue 3 board still has a soldered in ula on it so i just placed the MK4 ula over it for the piurposes of taking a photograph.

Image
Image
Image
Image
Image
Image

@Moggy... the cats out of the bag now huh :lol:
what's that Smell.... smells like fresh flux and solder fumes...
User avatar
Paul
Posts: 1546
Joined: Thu May 27, 2010 8:15 am
Location: Germanys west end

Re: Oh no! Not another ULA.

Post by Paul »

Thanks, that looks good.
Would a replacement DC-DC converter (recom) instead of 7805 still fit?
In theory, there is no difference between theory and practice. But, in practice, there is.
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Oh no! Not another ULA.

Post by Andy Rea »

i think so i measure the gap between pcb's at 9.5 mm when the MK4 is mounted in a turned pin socket. the 1A 5v recoms are 7.5mm thick, but you might have to make it's leads a little longer. so that it cann lay on its back.

regards
what's that Smell.... smells like fresh flux and solder fumes...
Moggy
Posts: 3333
Joined: Wed Jun 18, 2008 2:00 pm

Re: Oh no! Not another ULA.

Post by Moggy »

I think most of us lay the Recom/Traco types on their back anyway so no problem I would have thought.

Can't wait for them to be on sale though I may have to sell MY TS1500 to buy them! :twisted: :lol:
User avatar
Paul
Posts: 1546
Joined: Thu May 27, 2010 8:15 am
Location: Germanys west end

Re: Oh no! Not another ULA.

Post by Paul »

I'm also looking forward to get my hands on the enhanced version :ugeek:
In theory, there is no difference between theory and practice. But, in practice, there is.
Lardo Boffin
Posts: 2203
Joined: Sat Nov 26, 2016 2:42 am

Re: Oh no! Not another ULA.

Post by Lardo Boffin »

Exciting times!
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
User avatar
Andy Rea
Posts: 1606
Joined: Fri May 09, 2008 2:48 pm
Location: Planet Earth
Contact:

Re: Oh no! Not another ULA.

Post by Andy Rea »

Little update,

pretty much proved the device works as expected, missed a pull up resitior off, and a capacitor LOL.

i still plan to produce 2 versions, standard and enhanced

Standard version plug in and go. composite video 1v p-p into a 75 Ohm load ( most tv's and monitors)

Enhanced version will be approx. GBP 5 more expensive (different chip ) and will offer Clock doubling, inverse video, inverse border, M1not, and a constant 3.25Mhz output for people with zonx or other sound cards that need the clock. of course to use these features 5 extra wires need soldering to connect the address lines that are not present at the ULA socket.

Things that are different between this enhanced version and my really old altera design ( that had clock doubling ) .. The reset wire and resistor are gone. you can still lock the features set but resetting requires a) a power cycle. or b) exciting code at memory address 0. i.e an external system reset, causing the cpu to start exciting code at address - or a deliberate RAND USR 0 .

Clock doubling in FAST mode still requires a POKE 1001,x ( x doesn't matter) but you no longer need to set a feature bit to allow this.
Rompatch is also automatic, this allow easier switching back to slow mode from fast when in clock doubled mode.

so currently the control bits are as follows, we now have 2 spare bits.... what to do with them ???

Code: Select all

//=================================================================================
// FOR REFERENCE
//
// bit 0,	0 == normal operation of poke code,
//		1 == lock this setting (all bits of this write cycle locked)
//		(RESET BY a RESET automatically genrated whenn cpu excutes instruction at memory location zero)
//
// bit 1,	0 == 
//		1 == 
//				
//
// bit 2,	0 == uk/us select read normally
//		1 == uk/us select read inverted
//	
// bit 3,	0 == 
//		1 == 
//	
// bit 4, 	0 == Video normal
//		1 == Video inverted 		// video and border
//
// bit 5,	0 == border normal
//		1 == border inverted		// just border
//
// bit 6,	0 == M1not disabled
//		1 == M1not enabled
//
// bit 7,	0 == Turbo Off
//		1 == turbo On				// also activates Rompatch, patches 1 byte in rom to allow easier switching from fast to slow in basic
finally i estimate ( and thius is a rough guess based on todays prices )
Standard ULA to cost 20 GBP + postage cost (currently GBP 8.75 to most of Europe)

Enhanced ULA to cost 25 GBP + postage cost (currently GBP 8.75 to most of Europe)

Image
Image
Image
Image
Image

Those wires... (if ya know, ya know !)

regards Andy

P.s those faint diagonal lines seem to be a rolling shutter effect and you cant see them in real life )
what's that Smell.... smells like fresh flux and solder fumes...
Post Reply