Search found 1093 matches

by Lardo Boffin
Sun Dec 15, 2019 6:58 pm
Forum: Hardware
Topic: Earliest known ZX81?
Replies: 5
Views: 76

Re: Earliest known ZX81?

Very nice! Was it a kit build? I have had a few early ones (but not that early!) with ZX80 PSUs and cables that looked like they might be. My assumption was that if they bought a kit version they didn't get a PSU etc. and therefore used one that was easily available at the time.
by Lardo Boffin
Sun Dec 15, 2019 6:17 pm
Forum: Hardware
Topic: vLA81 ULA and 16/32K internal RAM
Replies: 20
Views: 208

Re: vLA81 ULA and 16/32K internal RAM

1024MAK wrote:
Sun Dec 15, 2019 5:48 pm
Lardo Boffin wrote:
Sun Dec 15, 2019 5:29 pm
I quite liked the Sinclair ROM bodge
:shock: Image

You mean ‘mandatory modification’ surely :lol:

Mark
Did I say bodge? I meant resource scarcity inspired improvised technical adjustment.
by Lardo Boffin
Sun Dec 15, 2019 5:29 pm
Forum: Hardware
Topic: vLA81 ULA and 16/32K internal RAM
Replies: 20
Views: 208

Re: vLA81 ULA and 16/32K internal RAM

Excellent post. They are there to be used and abused imo. not polished or put in glass cabinets. The first thing I did to my 80 was fit a switching reg, then ripped the guts out of the modulator to fit a composite board then finally a new ROM for ZXpand use and ended up with a much better tooter. M...
by Lardo Boffin
Sun Dec 15, 2019 12:47 pm
Forum: Hardware
Topic: I got a ZX80!
Replies: 7
Views: 104

Re: I got a ZX80!

Thanks, I'll see if I can get one the same type from Mutant Caterpillar that will involve no soldering to the board. As an aside, the other week I got a very, very early ZX81 (8106 Modulator, 8102 ULA, 8028 RAM) which actually had a ZX80 PSU with it, the same ZX80 type cassette and RF cables and sl...
by Lardo Boffin
Sun Dec 15, 2019 12:43 pm
Forum: Hardware
Topic: vLA81 ULA and 16/32K internal RAM
Replies: 20
Views: 208

Re: vLA81 ULA and 16/32K internal RAM

Presumably the major issue with bent pins on an IC is that it makes maintenance more difficult in the future? Would it be possible to fit a low profile socket, then fit another socket (pins bent out) and put the IC in that? Only the sandwich socket is modified and the RAM chips are easily swappable?...
by Lardo Boffin
Sat Dec 14, 2019 9:08 pm
Forum: Hardware
Topic: vLA81 ULA and 16/32K internal RAM
Replies: 20
Views: 208

Re: vLA81 ULA and 16/32K internal RAM

Thanks Chris. Just one or two questions.... :D :D * I assume L1 needs to be changed to L2? * With the mod as shown the zeddy has 32K of RAM? * Does that leave it in a state where most / all commercial software will still work? (Concerned that games that expect things to be in a specific RAM location...
by Lardo Boffin
Sat Dec 14, 2019 8:53 pm
Forum: Hardware
Topic: I got a ZX80!
Replies: 7
Views: 104

Re: I got a ZX80!

I have a programmer. But to fit a newer one on a standard eprom would need an adapter on the board and that wouldn't fit at all (and I don't want to make any changes at all to the actual board, even soldering). I thought a ROM-el would fit, but it's a gnat's whisker too tall. I remember seeing an o...
by Lardo Boffin
Sat Dec 14, 2019 7:31 pm
Forum: Hardware
Topic: I got a ZX80!
Replies: 7
Views: 104

Re: I got a ZX80!

Got this today. And it was a bargain if I do say so! I discovered that it has a vigin exp port too, never scratched by a RAM pack, much to my delight. It has a few marks and a little rip in a lower corner. It came with a ZX81 ROM and ZX81 keyboard overlay. I removed the overlay and as there's not m...
by Lardo Boffin
Sat Dec 14, 2019 7:30 pm
Forum: Hardware
Topic: vLA81 ULA and 16/32K internal RAM
Replies: 20
Views: 208

Re: vLA81 ULA and 16/32K internal RAM

I've done a few of these (and have done a lot of fiddling with various configurations and written a lot of emails bothering Mr Ingley with silly questions) and there is no need to cut any tracks, just bend out 4 pins (1,2,23,26) of the 32k RAM chip and connect to address lines A11 to A14. Note that...
by Lardo Boffin
Sat Dec 14, 2019 5:12 pm
Forum: Hardware
Topic: vLA81 ULA and 16/32K internal RAM
Replies: 20
Views: 208

Re: vLA81 ULA and 16/32K internal RAM

Thank for the links. I was wondering how using one of these to get 32K would work in relation to your mod process?

Presumably the same tracks would be cut. Would the part where you reconnect the two cut tracks be connected directly to a pin on the vLA?
99296B80-6AF1-4C58-9EED-2F0452085BE3.jpeg