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Re: 1K lowres games in machinecode on a Lambda
Posted: Sat Jun 11, 2022 2:11 pm
by David G
Good idea
On the emulators, poking a 127 [opcode for ld a,a] to the screen
- On EightyOne it prints a space
7Fh 127
3Fh 'Z'
So maybe NO$ZX is disregarding BIT 6
Re: 1K lowres games in machinecode on a Lambda
Posted: Sat Jun 11, 2022 3:35 pm
by mrtinb
If you make small programs I can test them on both ROMs, on real hardware, when I have my setup running.
Re: 1K lowres games in machinecode on a Lambda
Posted: Sat Jun 11, 2022 4:33 pm
by dr beep
David G wrote: ↑Sat Jun 11, 2022 2:11 pm
Good idea
On the emulators, poking a 127 [opcode for ld a,a] to the screen
- On EightyOne it prints a space
7Fh 127
3Fh 'Z'
So maybe NO$ZX is disregarding BIT 6
What NO$ZX is doing is the same what my 1997 emulator did.
That is why I coded the 2020 emulator
1) speeding up
2) adding my games to run on the emulator.
Those opcodes can be quite handy in games.
See my game DIGG-IT.
When you jump the player will not go too high. That is because above the player are hidden opcodes to prevent going up.
On dropping only a platform is allowed under the player.
Re: 1K lowres games in machinecode on a Lambda
Posted: Sun Jun 12, 2022 2:34 am
by David G
"the 2020 emulator" is
SP-2-ZX81 for the 48K ZX Spectrum. What was the 1997 emulator called?
Re: 1K lowres games in machinecode on a Lambda
Posted: Sun Jun 12, 2022 8:53 am
by dr beep
ZX81EMULATOR
https://spectrumcomputing.co.uk/entry/1 ... 1-Emulator
The 2020 was called so it also had the nr 2 in the name, indicating a second emulator.
Re: 1K lowres games in machinecode on a Lambda
Posted: Tue Jun 14, 2022 12:19 am
by David G
mrtinb wrote: ↑Sat Jun 11, 2022 3:35 pm
If you make small programs I can test them on both ROMs, on real hardware, when I have my setup running.
Here is the small program
This pokes a 127 [opcode for ld a,a] to the screen. On a ZX81 this simply appears as a space, on some emulators it prints a 'Z'
Re: 1K lowres games in machinecode on a Lambda
Posted: Tue Jun 14, 2022 11:01 pm
by mrtinb
So I've typed the POKE on both ROMs on real hardware.
"Original" ROM gives blank screen with OK.
And the "updated" ROM gives also a blank screen with OK.
