UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Specific Vintage Equipment > Vintage Computers

Notices

Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

Closed Thread
 
Thread Tools
Old 24th Mar 2020, 12:50 pm   #161
John Earland
Hexode
 
Join Date: May 2013
Location: Middlesbrough, North Yorkshire, UK.
Posts: 442
Default Re: Zx81

I tried the '81 this morning and left it running without modifications for just over two hours - unfortunately the same thing happened. The unit rebooted and then the picture was lost. I tried retuning the TV but it was clear that it was the computer. I squirted the freeze spray onto the underside of the PCB where the ULS is situated and immediately the picture returned. I guess this means a new ULA? :-(
John Earland is offline  
Old 24th Mar 2020, 1:00 pm   #162
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

It does look that way, sorry. You could check other things, for example make sure the +5V supply is 5V when the machine is cold and is still 5V when the machine is running warm and the fault has appeared.

Cooling the ULA may just allow it to run on a bad supply voltage for a little bit longer (stranger things have happened). But at the moment it does look as though you have a thermal fault on your ULA.
SiriusHardware is online now  
Old 24th Mar 2020, 1:41 pm   #163
Slothie
Octode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,287
Default Re: Zx81

Build the world's first water cooled ZX81!
Slothie is offline  
Old 24th Mar 2020, 1:46 pm   #164
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

Some of the retro parts sellers sell a full length low profile heatsink specifically to go on the ULA which, even when working 100%, normally runs quite hot. But I fear that this ULA may already be beyond redemption.
SiriusHardware is online now  
Old 24th Mar 2020, 2:09 pm   #165
Slothie
Octode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,287
Default Re: Zx81

I did a look around for replacement ULAs and they're all out of stock. - replica cpld based replacements furnish lots of dead links. I guess it would require more dedicated research than the 10 mins I spent.
Slothie is offline  
Old 24th Mar 2020, 3:58 pm   #166
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

This source

https://retrorevivalshop.co.uk/index...roducts_id=560

...claims to have five of the ones made by the New Zealand guy (who also makes the Vdrives for the Spectrum). Have not used this source myself.
SiriusHardware is online now  
Old 24th Mar 2020, 6:36 pm   #167
John Earland
Hexode
 
Join Date: May 2013
Location: Middlesbrough, North Yorkshire, UK.
Posts: 442
Default Re: Zx81

Oh-thanks for that! I’ll take a look-would love to have this little fella up and running again!
John Earland is offline  
Old 24th Mar 2020, 7:01 pm   #168
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

In the meantime maybe you can get your ZX81 fix by fitting the CCU PCB to the other ZX81, the one with 'dark' video output.
SiriusHardware is online now  
Old 24th Mar 2020, 7:50 pm   #169
electronicskip
Nonode
 
electronicskip's Avatar
 
Join Date: Oct 2010
Location: Gloucester, Glos. UK.
Posts: 2,148
Default Re: Zx81

All this chat about ZX81s has made me get mine out of hibernation as im stuck at home now for the duration .
Might get the old Speccy out too and have a bash at Horace goes skiing !
__________________
Oh I've had that for years dear!!
electronicskip is offline  
Old 24th Mar 2020, 9:08 pm   #170
Timbucus
Octode
 
Join Date: Mar 2019
Location: Barry, Vale of Glamorgan, Wales, UK.
Posts: 1,362
Default Re: Zx81

Mine has been out a few times as well over the last few weeks - must try again now I have a tzxduino loading some .p files into it!

My Spectrum and the new Next are always on my desk...
Timbucus is offline  
Old 24th Mar 2020, 9:22 pm   #171
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

Have any of you seen the new '81 software titles produced by Paul Farrow? His whole website is a treasure trove of interesting ZX things but here he's done a 3D isometric maze puzzle game in the style of Knight Lore / Alien 8 for the ZX81.

http://www.fruitcake.plus.com/Sincla...heElements.htm

Free to download, I believe.
SiriusHardware is online now  
Old 24th Mar 2020, 9:26 pm   #172
electronicskip
Nonode
 
electronicskip's Avatar
 
Join Date: Oct 2010
Location: Gloucester, Glos. UK.
Posts: 2,148
Default Re: Zx81

There was a game called 3D Monster maze for the ZX81 was pretty good considering the constraints of memory.
__________________
Oh I've had that for years dear!!
electronicskip is offline  
Old 24th Mar 2020, 9:31 pm   #173
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

Oh, that was virtually the 'Killer App' for the ZX81. I don't think anyone didn't have that game.
SiriusHardware is online now  
Old 24th Mar 2020, 9:52 pm   #174
Slothie
Octode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,287
Default Re: Zx81

I remember playing that on my friends ZX81. A year or so previously I'd written a 3d maze program for my Commodore PET and I remember being annoyed I hadn't bothered to sell my game as everyone I knew with a Zx81 had 3D Monster Maze
Slothie is offline  
Old 24th Mar 2020, 10:53 pm   #175
John Earland
Hexode
 
Join Date: May 2013
Location: Middlesbrough, North Yorkshire, UK.
Posts: 442
Default Re: Zx81

I never had a zx81-Spectrum was my first and I loved Horace and the Spiders!
John Earland is offline  
Old 24th Mar 2020, 10:59 pm   #176
Slothie
Octode
 
Join Date: Apr 2018
Location: Newbury, Berkshire, UK.
Posts: 1,287
Default Re: Zx81

I never had a Spectrum but I was very impressed with it at the time. It's no wonder it spawned the careers of many a computer programmer, you got a lot of computer for not much money. It's a shame Sinclair perused the business market and didn't realise what an opportunity he had in the home computer/games market.
Slothie is offline  
Old 25th Mar 2020, 12:09 am   #177
emeritus
Dekatron
 
Join Date: Jan 2012
Location: Brentwood, Essex, UK.
Posts: 5,303
Default Re: Zx81

My recollection is that the ZX81 manual encouraged you to PEEK into the memory and see what was in the various locations. A good way of getting an insight into to what was going on. Data for BASIC programs usually had to be stored in REM statements.
emeritus is online now  
Old 25th Mar 2020, 9:42 am   #178
John Earland
Hexode
 
Join Date: May 2013
Location: Middlesbrough, North Yorkshire, UK.
Posts: 442
Default Re: Zx81

Quote:
Originally Posted by emeritus View Post
My recollection is that the ZX81 manual encouraged you to PEEK into the memory and see what was in the various locations. A good way of getting an insight into to what was going on. Data for BASIC programs usually had to be stored in REM statements.
I never quite got PEEK (still don't to be honest) but as I'm going to be working from home for some time, I might get out my old manuals and start!
John Earland is offline  
Old 25th Mar 2020, 1:27 pm   #179
electronicskip
Nonode
 
electronicskip's Avatar
 
Join Date: Oct 2010
Location: Gloucester, Glos. UK.
Posts: 2,148
Default Re: Zx81

Did anyone have any experience of the Sinclair ROM carts?
They are very collectable nowadays , but they have always eluded me.
__________________
Oh I've had that for years dear!!
electronicskip is offline  
Old 25th Mar 2020, 1:48 pm   #180
SiriusHardware
Dekatron
 
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,471
Default Re: Zx81

For the ZX81? They were available for Spectrum (for the interface II), but I have never been aware of any made for the ZX81.

For some time now there has been a ZX81 hardware add-on called the ZXpand (see what they did there) which, among other functions, allows ZX81 software in .P format etc to be loaded from flash media. There was, possibly still is, a custom version of the ZX81 keyboard membrane available which has the ZXpand specific keywords / commands on it.

If we want to wax nostalgic about the Spectrum, maybe it's time for a specific thread about that too?
SiriusHardware is online now  
Closed Thread

Thread Tools



All times are GMT +1. The time now is 11:29 am.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Copyright ©2002 - 2023, Paul Stenning.