Search found 29 matches

by Woodster
Tue Jan 21, 2020 6:35 pm
Forum: Programming
Topic: How is a 3D game like Ant Attack implemented?
Replies: 20
Views: 588

Re: How is a 3D game like Ant Attack implemented?

https://spectrumcomputing.co.uk/index.p ... 6&id=21605

Something quite similar looking although not even close to being in the same league in game play!

Source code is there too if you want to take a look.
by Woodster
Thu Nov 21, 2019 2:49 pm
Forum: Music
Topic: Cant find the program with digitized music?
Replies: 26
Views: 2325

Re: Cant find the program with digitized music?

I tried it on the latest SpecEmu in both 128/48k mode, so I have no doubt about the quality of the emulation. Probably I overlooked something, does anyone know how to play this tune? You could use the "Boost saving tone" option in the Tape options to boost the MIC output to an audible level. It mig...
by Woodster
Thu Nov 21, 2019 2:48 pm
Forum: Music
Topic: Cant find the program with digitized music?
Replies: 26
Views: 2325

Re: Cant find the program with digitized music?

Last time I tried, it worked fine on my +2A from the covertape itself. No idea why it might fail under emulation. So the +2A (and presumably the 128K too then) produce audible MIC output through the TV speaker with the Beeper bit off? The reason for the silence in SpecEmu is that it's stated in the...
by Woodster
Tue Oct 15, 2019 6:22 pm
Forum: Programming
Topic: Short beeper routines in assembly
Replies: 49
Views: 6214

Re: Short beeper routines in assembly

Seven.FFF wrote:
Tue Oct 15, 2019 5:18 pm
I think you are right. IMO it should say “ Access to ports between 0x4000 and 0x7ffe with the low bit SET (i.e. when the ULA's own port is not being accessed) is subject to contention on every T state”
It should indeed say when the low bit is set.
by Woodster
Sun Aug 18, 2019 8:45 am
Forum: Emulators
Topic: Starting emulator - help with basics of Z80 timing needed
Replies: 17
Views: 1397

Re: Starting emulator - help with basics of Z80 timing needed

I did not expect an internal operation on the z80 to be contended? They're contended because the ULA doesn't look at the control bus for MREQ signals and the like and only respond to what it sees on the address bus which is the last address latched, or the address of the JR offset byte in this case...
by Woodster
Sat Aug 17, 2019 4:25 pm
Forum: Emulators
Topic: Starting emulator - help with basics of Z80 timing needed
Replies: 17
Views: 1397

Re: Starting emulator - help with basics of Z80 timing needed

Or another way you can think of it in the opcode breakdowns is to always try to think what is on the address bus at any moment in time as the ULA will contend based on the address bus contents rather than any specific register pair. So your pc+1 address fetching the offset (25 in your example) is th...
by Woodster
Sat Aug 17, 2019 4:22 pm
Forum: Emulators
Topic: Starting emulator - help with basics of Z80 timing needed
Replies: 17
Views: 1397

Re: Starting emulator - help with basics of Z80 timing needed

Looks like you understand the concept of how to implement the contention just fine but the pc:n (or reg:n entries in some opcodes) are relative to the starting values of the registers at the start of opcode execution. Hence your pc+1:1x5 will be using pc+1 as meaning 25001 rather than as being 25002...
by Woodster
Fri Aug 16, 2019 1:01 pm
Forum: Emulators
Topic: Starting emulator - help with basics of Z80 timing needed
Replies: 17
Views: 1397

Re: Starting emulator - help with basics of Z80 timing needed

EX AF,AF' takes 4 t-states in total to fetch and process.
by Woodster
Sat Jun 15, 2019 3:20 pm
Forum: Games/Software
Topic: Mr Do coming soon to Spectrum
Replies: 33
Views: 3346

Re: Mr Do coming soon to Spectrum

This is brilliant! Although obviously I died quickly just like in every other game!
by Woodster
Mon May 27, 2019 3:47 pm
Forum: Games/Software
Topic: I've Never Played Fairlight
Replies: 30
Views: 2115

Re: I've Never Played Fairlight

PeteProdge wrote:
Mon May 27, 2019 3:24 pm
And I also want to add - Elite. Sorry everyone, but never really delved into it.
Same, never been into Elite at all. Nor Fairlight.