Sinclair ZX80 / ZX81 / Z88 Forums

On regular Donkey Kong, you can't go up or down a ladder while carrying the hammer. Yes, I wasn’t sure if being able to or NOT being able to was the bug. Anyway I hope the control issues can be sorted out as otherwise it’s a really smashing little game, one of the 81’s finest. Appreciate the commen...

I agree, great little game. Support for the joystick on my ZXPand would be nice if possible. Well, neither myself or the other D currently own a ZXPand, so we didn't develop for it. If you can point me in the direction of hardware specs, I'd love to add it in. Glad you enjoy the game. It's certainl...

If it works on real kit and the windows version of Eighty One I would have thought the problem lies at your end. Is your emulator a straight Linux one or running through retro-arch? I only ask as I have had endless hassle keyboard wise when running a zx81/spectrum emulator through retro-arch. As I ...

TMD2003 wrote: ↑Fri Apr 16, 2021 8:55 pm And I thought Duke Nukem Forever was the ultimate case of "stuck in development hell". I also hope Jari Mäenpää doesn't read this forum and get any ideas.

In the absence of any entries to my wondrous competition recently, I'll give this a go.

Feel free to include it on your competition page!

D

1024MAK wrote: ↑Wed Mar 24, 2021 9:12 pm 74LS244 and 74LS245 data buffers are normally reliable, but just like anything else, they can fail.

Mark

I've ordered a few and should have them in a couple days. I'll let you know.

So, I'm in the the process of tracing data and address lines. I notice they run through 2 separate ICU's. 74LS244 and 74LS245 data buffers. How often do these things fail? I haven't traced them yet, but I'm curious. And even with good continuity from the pins, if the ICS are bad, I assume the machi...

So, I'm in the the process of tracing data and address lines.

I notice they run through 2 separate ICU's. 74LS244 and 74LS245 data buffers. How often do these things fail? I haven't traced them yet, but I'm curious.

Update! Making progress, I think. I replaced all the power related diodes, and socketed the memory chips. Still no video. I tested the ROM in my 1500, and it worked fine. Good news! I also tested the Z80 on my 1500 and got a black screen. Hmm...maybe bad Z80. I tried my working Z80 in the bad machin...

Check / test also diodes D5 and D6. Also, I don’t know how good this design is with no load. The 4116 DRAM chips draw typically about 20mA to 30mA each when being accessed. Try connecting some 1k ohm or 820 ohm resistors across the +12V and 0V/GND to see if the voltage drops nearer to the maximum s...

Well, I've made some progress. After removing the memory, I discovered the replacement Q2 transistor was shot. I replaced it, and got proper voltage...ish. I'm now showing 13.5V on the 12V rail and -5.4 on the -5 volt rail. I'm guessing the D1 12V Zener is shot and will be replacing when it arrives....