Spectrum Computing

Port $38 is an even port, so the ULA will respond even if an addon is plugged in externally. And if the upper address byte is not explicitly put on the bus, it won’t even get a consistent keyboard read. The best you’d get is a sample of the EAR signal.

markusr I'm posting this on behalf of Xalior who doesn't post here. He says he wrote https://github.com/StalePixels/trampoline_examples with examples of how to use "unlimited executable memory" for DOTN and NEX files, building from the same codebase even. If you want more direct 1:1 help,...

Oh lol, I went back and reread your question this morning. You're not trying to make your assembler generate DOTN commands, you're trying to build your assembler as a DOTN command! While my explanation of how they work under the hood might be interesting, it doesn't help answer your question. I'll s...

DOTN is not a separate file type at all, it’s just a dot command. That’s probably why you’re not finding much info. The main thing to know is that, unlike standard esxDOS which only allows dot commands to be max 8KB (filling one page of divMMC RAM mapped between $2000..3FFF), NextZXOS allows them to...

Z80 as in Zilog’s CPU, with X added for the unknown eXciting factor. I read this on an ex-Sinclair Radionics and Science of Cambridge engineer’s history/reminiscence website the other day.

I'm not intending to speak for Peter or Einar here, but from my perspective, the real jewel in the SC crown is the ZXDB database of titles and metadata, which has been made available to use for free by anybody. Hosting and downloading of the indexed game files is a separate thing, and usage goes str...

I would prefer to see all that tacky fake CRT stuff included in displays rather than devices that output video signals. It really has no place place in anything but a display, and even then, only for the people who actually want to see the fake stuff. It reminds me of rednecks and chavs that deliber...

Mods are needed! So yes, obviously it's possible to do any mod at all on any Speccy or Next game. What did you have in mind? Just design it, then code it :D I'm not trying to be flippant, but at 14MHz I'm able to get about halfway through Outrun stage 3 most times using the keyboard, which is the s...

spectrum next and other systems with fast CPUs? I'm not sure if 28MHz is a thing, last time I was interested in super spectrums, informations about 28MHz were little bit confusing). The Next has 3.5, 7, 14 and 28MHz. It's as simple as pressing NMI+8 to toggle between the four speeds while you're ru...

You are probably right in getting it to work with the Sega pads makes the most sense. I have schematics for 3- and 6- button Sega controllers, if you're interested in exploring that part too. Not for the host side, but I think you're going to do that part with a pico, and you have it well-covered.

Seven.FFF wrote: ↑Tue Nov 14, 2023 7:21 pm but I think the wiring was for 3 button quadrature mice

Darn it, this was meant to be a reply to this thread.

I'm not sure, because I never had any interest in the C64/Amiga scene, but I think the wiring was for 3 button quadrature mice, and while the sticks always had the potential to coexist for the same wiring, nobody apart from much more recent hobbyists ever made any. So nobody made any games either. S...

There's plenty of 3 button DE9 joysticks out there. You just have to pick the wiring you want!

It is possible to build a Kempston interface that populates both the Joystick register and the Mouse register at the same time, so both items will work in it like an autodetect, though I'm not sure that all software would expect that, and the joystick and mouse data might conflict. They can indeed ...

Yep it’s bitten a few people. The reason it’s like that, btw, is because the Pi is conceptually a hat for the Next rather than the other way round. And it lets you use stacked headers like this, and add further hats to the Pi as well. https://dl.dropbox.com/scl/fi/6js414t6i3oc9581bcgre/Photo-Nov-05-...

I'll probably spend more time with the 128 and BBC cores. Yes, and it should be possible to put PiTubeDirect on a Pi Zero, attach it to the 2x20 header on the Xberry Pi, and use it with Hoglet’s BeebFPGA Next core. Just remember that Pi Zeros on Nexts/N-Gos/Xberry Pis have a 2x20 female header atta...

Yes, square waves have odd harmonics. That is, a perfect square wave is equivalent to a bunch of sine waves at 1, 3, 5, 7 … Infinity times the base frequency, tailing off in amplitude as it goes higher, all superimposed on top of each other. The Speccy beeper is far from a perfect square wave but un...

Announced on main Next and Next games facebook groups, Next forum and Next discord.

The Xberry Pi is a Spartan 6 FPGA clone of the ks1 Next issue 2B board, but sized and laid out to fit a Pi case. The extreme shrinking means some of the connectors and buttons are not present, or only present on pin header pads you can break out to connectors and buttons yourself. But because it can...

On some models of Spectrums the printer buffer doesn’t exist and has been replaced with additional sysvars. Amstrad did not care much about backward compatibility with the ZX Printer. If devs are going to the trouble to play nicely with BASIC it’s worth making programs play nicely on all models. Thi...

Even if you want to use BASIC and/or printing early on in your loading process, once you have called into your machine code entry point with USR, you can reclaim the remaining space by disabling interrupts and calling LD-BYTES directly from machine code, to load one final headerless block over the t...

Sure, send it my way by PM if you like. I have both ks1 and ks2 Nexts to test it on.

Devs and end users are treating N-Gos as functionally identical to ks1 Nexts as far as software is concerned, so we shouldn't expect any problems. Never hurts to check though!

Not a problem, I’m glad you solved it.

Ben does maintain a hardware cross-compatibility list but the ZX-VGA-JOY is not on it. I think it’s still worth talking to him so he can add your findings to the list.

It does make more sense now you said you’re using another external device that generates video output.

High horse?! Where are you getting that from? Just trying to help.