Search found 212 matches

by TMAOne
Sat Oct 05, 2013 12:24 am
Forum: GAMES
Topic: New game finally available after 30 years in development!
Replies: 2
Views: 2702

New game finally available after 30 years in development!

Deflection.jpg Well, sort of. Here's the story: When I bought my Sinclair kit in 1982, a friend of mine who was studying computer science, (and just happens to be a friggin' genius), came down with the unusual Adult Onset Juvenile Diabetes. To make his hospital stay more interesting, I smuggled him...
by TMAOne
Thu Aug 29, 2013 11:57 pm
Forum: WANTED
Topic: Timex Sinclair 1000 ULA & Timex Sinclair 2020 tape recorder
Replies: 9
Views: 12959

Re: Timex Sinclair 1000 ULA & Timex Sinclair 2020 tape recor

Hi Paulo,

If you haven't found a donor unit already, there is a discussion here: viewtopic.php?f=7&t=1180 about replacement ULA's that have become available from new old stock.

See eBay item: 261273794335

Ian
by TMAOne
Mon Aug 19, 2013 9:13 pm
Forum: Hardware
Topic: Remanufactured ULAs?
Replies: 57
Views: 25065

Re: Remanufactured ULAs?

What's the most interesting ULA failure you've ever seen? I have one that overwrites the first character of the active line across all unwritten positions of the last line of the general display. For example, for J = 1 to 5 scroll print J next J ... would produce a 1 with the rest of the line fille...
by TMAOne
Sun Jul 14, 2013 7:26 am
Forum: Lambda 8300/ Power 3000 Lounge
Topic: Lambda 8300
Replies: 20
Views: 31639

Re: Lambda 8300

There are more knowledgeable folks about than I, but I'll tell you what I found with my relatively recently acquired example. What is the DC voltage & amperage in? I've seen it listed between 10.8V 500ma and 12V Mine came with a monster 12V 1.8A combination transformer and cosmic ray deflector. That...
by TMAOne
Wed May 29, 2013 5:15 am
Forum: Hardware
Topic: 16K RAM Pack Schematic / Chip Layout
Replies: 71
Views: 47801

Re: 16K RAM Pack Schematic / Chip Layout

Thank-you for the links. Interesting material. I guess there's quite the science to diagnosing the spookier classes of errors. The tiny program I have already is, (I see now), a simple "march algorithm", intended to spot "stuck at" faults. It is good enough to figure out if a 4116 has gone to chip h...
by TMAOne
Wed May 29, 2013 12:49 am
Forum: Hardware
Topic: 16K RAM Pack Schematic / Chip Layout
Replies: 71
Views: 47801

Re: 16K RAM Pack Schematic / Chip Layout

Success!

My jury-rigging had caught up to me. I had a cold solder joint at the diode.

The board is now merrily testing 16K. Write 0, read back 0, write 255, read back 255, working so far. (This is with a good pack.) So the circuit works, and you're a genius (again) PokeMon.
by TMAOne
Tue May 28, 2013 11:41 pm
Forum: Hardware
Topic: 16K RAM Pack Schematic / Chip Layout
Replies: 71
Views: 47801

Re: 16K RAM Pack Schematic / Chip Layout

So when you try to read (with PEEK) from S0 and $8000 - do you get same values ? And try $0001 and $8001 - will be the same ? Yes, what I'm seeing starting the loop at $8000, is an echo of what is at $0000. After a POKE, the value remains unchanged. I tried playing with the diode again but it doesn...
by TMAOne
Tue May 28, 2013 9:52 pm
Forum: Hardware
Topic: 16K RAM Pack Schematic / Chip Layout
Replies: 71
Views: 47801

Re: 16K RAM Pack Schematic / Chip Layout

* A15 from main board D'oh! That's me, my bad. I got so hung up on soldering pins 5,6, 8, & 9 together I forgot to connect them to A15, then when I checked I was looking for vertical lines. Okay, now it boots. The RAM pack is not seen yet however. I have been using a working RAM pack for initial ex...
by TMAOne
Tue May 28, 2013 7:01 pm
Forum: Hardware
Topic: 16K RAM Pack Schematic / Chip Layout
Replies: 71
Views: 47801

Re: 16K RAM Pack Schematic / Chip Layout

Still "no go". Yes, I remembered to power the chip. I now have the 4148 in circuit. (Tried 2 different diodes, and tried reversed polarity just in case--all "no go".) So I did "the experiment" you first thought of PokeMon. WIth A14 of the RAM pack taken to ground instead of the 74HTC02 gate output, ...
by TMAOne
Tue May 28, 2013 6:51 am
Forum: Hardware
Topic: 16K RAM Pack Schematic / Chip Layout
Replies: 71
Views: 47801

Re: 16K RAM Pack Schematic / Chip Layout

My 74HCT02 chip arrived today, so I wired the circuit up, with a known good ZX81 and RAM pack. It won't boot for me. Admittedly, the way I've implemented it is far from elegant, but I've checked the connections and they seem to be correct. The RAMCS and A14 connections have been "broken" by using ce...