Redgate gets a Zeddy

[redgatemodels]

I appear to have agreed to buy a ZX81, untested, but looks OK. 1A PCB. I'll make an adaptor lead for my Speccy PSU and give it a test when I get hold of it.

Let the fun begin, how soon before 3D Monster Maze is loaded I wonder

[mrtinb]

You'll need a 16k RAM pack for that.

[redgatemodels]

Plan is to do an internal 16K conversion

[mrtinb]

Plan is to do an internal 16K conversion

https://www.ebay.com/itm/256060383699

https://www.ebay.com/itm/196088813344

[redgatemodels]

Plan is to do an internal 16K conversion

https://www.ebay.com/itm/256060383699

Yep, that's the one

[Lardo Boffin]

A socket and a RAM chip, about £5:

http://blog.tynemouthsoftware.co.uk/201 ... n.html?m=1

Edit - see this post though!

https://www.sinclairzxworld.com/viewtop ... 353#p51353

[1024MAK]

Nah, all those are easy peasy lemon squeezy solutions. If you are a real Sinclair fan, you want the hardcore modification such as this one

Mark

[redgatemodels]

Well it’s in hand, a bit tatty and has extra holes in the bottom case as it’s been screwed to a wall in the past

It came with an issue 4 Speccy that had the same treatment. Got the pair for 40 quid.

Ordered a 3.5mm jack and 2.1mm socket to make a power supply adaptor. Let’s see if it powers up next week sometime.

[redgatemodels]

So, let’s see where we are with the ZX81.

power lead adaptor made, tested positive tip, 11.87v

Connected to two different modern tvs there is what looks like an inverted screen, black background not white, but there is a visible white K cursor and some of the keys respond.

Opening it up there’s no noticeable damage, unlike the Speccy that came with it that has holes drilled in the pcb! Clearly the pcb tails are goosed, but the top face of the keyboard is dented, scratched etc so would be getting a new one anyway.

Here’s a couple of pics including some mods underneath? Are these factory?

So, the odd display, is that a function of using a modern tv, or is there something more sinister going on?

[1024MAK]

The components on the underside near the jack sockets are normally fitted on the component side. And yes, that’s work that was done in the factory.

I have no idea why you have an inverted display. Using a modern TV should not make any difference. The video signal is generated in the ULA.

Normally you either need some extra circuitry to invert the screen (or use a ULA replacement module or a modified ZX80 or a clone that has this feature).

Mark