Spectrum Computing

Couldn't you just lower RAMTOP automatically? Surely it's not that difficult to find the entry point to the CLEAR routine?

One advantage to a Lego design is you could make it smaller and then redesign it any time you got bored of it. Assuming you get a roughly 50/50 split between black and orange pieces. A site that kits it up for you does look neat, although personally I couldn't bring myself to use unofficial pieces. ...

Also bear in mind that the signal put out by the Speccy is outside the PAL spec, so a very modern display might just struggle syncing with it directly.

From the Zilog docs;

Each cycle in the HALT state is a normal M1 (fetch) cycle except that the data received from the memory is ignored and an NOP instruction is forced internally to the CPU. The HALT acknowledge signal is active during this time indicating that the proces-sor is in the HALT state.

Oh well. I can dream! Looks like a wireless keyboard would do the job. Anyone have any luck attaching a USB wireless keyboard via a PS/2 adapter? https://i.postimg.cc/ygHKn14n/e91ea6e5-2955-4a8b-9a6f-6966416d185b-cropped.jpg I'm pretty sure USB keyboards and mice have to support the PS/2 protocol i...

I doubt there is one. Most of the genre stuff is a throwback to the old WoS flat file arrangement and I'm not sure consistency was ever its strong point. It's not a great way of representing that kind of data in the real world either. Generally I'd take the approach of allowing multiple "tags&q...

Batman The Movie has a great soundtrack, although I'd put the Batwing level as my favourite of all:

Here's a question: How come AY music sounds so different on the CPC from the Spectrum? Is there some kind of hardware filter or amplifier involved? Spectrum AY music often sounds thin and weedy like that Firefly tune, whereas the CPC seems fuller and more resonant, more arcadey in a way. The CPC ha...

Ah yes "!" vs "M" if I recall. As one bank is used by +3DOS , I wonder what happens with that on the +2A/B , if its got anything in it or used, as in for the ram-disk. It's the same. +3DOS still reserves some for a disk cache and keeps the second screen free regardless of whethe...

The episode on which is based is called "No sax please. We're Egyptian" which is obviously spoofing "No sex please, we're British" so I'd suspect its a mistake.

Hmm, so, relatedly: are there any games that work on a 128/+2 but not on a +2/+3 purely because there isn't enough RAM? I doubt it. The Syntax for using the RAMdisk is entirely incompatible between the two, so that'd break thing in BASIC long before running out of RAM. In a pure m/code game, you ca...

It's not actually the same size ROM, the +2A/+3 has 64K of ROM, where the +2 has just 32K, although I don't think that matters here. The RAMdisk on the +2 is a very minimal implementation and can use all 5 extra 16K pages on the 128. I'd assume the directory structure is also pretty minimal. The RAM...

You probably only need find about 9 bytes somewhere: CALL original _usr_address EXX LD HL,$2758 EXX RET And then just call that in place of whatever the original USR was doing. Could possibly save another byte if the return value in BC doesn't matter at all. That way it shouldn't matter which RET ac...

I'm not really surprised, the Amstrad version (which is based roughly on the engine used for JSW2) is a fair bit faster and probably runs equivalent to a 7Mhz version. It's actually a bit more playable sped up somewhat, tbh.

IIRC the ram-paging scheme in 128/+2 grey is somehow different of that in the +3/+2A, the latter allows an all-ram mode, for example, but I'm not an expert. I think I've read somewhere the 128/+2 grey scheme allowed some type of gigascreen effect easier than the +3/+2A. The +2A/+3 paging mechanism ...

You can probably tweak it so it copies 6912*2 bytes instead of 6912 and make the data contiguous. I don't know anything about paging on the 128K though so I may be wrong. You can't arrange the memory such that both screens are contiguous (each one occupies the first 6912 bytes of a RAM bank, either...

Yes, a lot of LCD screens will, entirely as a side effect of their image processing, hide the flickering you'd normally see. The distinction is more obvious on an old school CRT.

Paging is really not that complicated. Essentially you're picking which bit of memory is located between 49152 and 65535. When you change the bank, all that memory at that location instantly changes. So any code or data you want to access needs to be below 49152 before you start swapping memory arou...

Thank you for sharing this - I've been wondering about it since you WOOT submission. This is the code from the basic generated by imagetozxspec. Is this all that is needed for a simple viewer? Ran in USR0 mode. 370 CLEAR 49151 380 POKE 23739,111 390 OUT 32765,21 400 LOAD "" CODE 49152 410...

You're not paying attention to your memory map. When you change the 128K banking you're paging out your copy routine (which is right at the top of memory). You'll also be paging out the memory that contains part of your second screen, if my back of a fag packet maths is correct.

One of those weird face things from Super Mario Bros 2? The ones that chase you once you pick up a key?

Please, see the build attached to the post (link at the bottom of the post). Prototype is already working and I'm not asking about technical challenges cause I'm aware of it already ;) I'm just asking in general: "Is it worth to use Gigascreen or better to switch to classic screen". Like ...

It can be very dependent on the exact images, but personally I find it varies from "mildly irritating on my eyes" to " absolutely headache inducing". It might be better on an LCD, where the frames sometimes get blurred together, but the results can be very display specific. Also ...

Dr beep wrote: ↑Thu Jan 04, 2024 2:17 pm QA56 M

Are you, by any chance, an octopus? I don't have nearly enough dexterity in my hands to manage that.

QA56 X

Would require a bit less contortion, although I still wouldn't call it nice.

Self modifying code tends to fall into one of two categories: 1) Simple stuff like storing a variable inline inside an instruction so LD, HL, nnnn has the nnnn value directly stored in the opcode. Slightly more advanced versions tweak the odd instruction itself to swap an XOR for an OR or a NOP mayb...