Search found 882 matches

by siggi
Fri Jul 05, 2019 12:00 pm
Forum: Emulators
Topic: XavSnap Anomalies
Replies: 5
Views: 437

Re: XavSnap Anomalies

When I ported Chopper Drop 3000 to be compiled by MCODER2, the basic program size got bigger than 16K (the generated machine code is inserted into REM in line 1). The the DFILE then moved above 32K (afaik it must be completely moved across the 32K boundary to avoid a crash). BUT THEN THE M1-LOGIC (w...
by siggi
Tue May 28, 2019 9:38 am
Forum: Sinclair Misc
Topic: Did the original ZX80 "new" ROM really contain.....
Replies: 3
Views: 806

Re: Did the original ZX80 "new" ROM really contain.....

As fa as I remember I read somewhere (in this forum???) something about the developer of this rom: he told, that the printer code was added in the final development phase just before releasing the ZX80. So maybe some prototype roms contains this code, but not the released roms.

Siggi
by siggi
Tue May 14, 2019 10:20 am
Forum: ZX BASIC
Topic: ZX81X2.ROM - and the big bang
Replies: 36
Views: 7740

Re: ZX81X2.ROM - and the big bang: compatibility problem?

Hi there seems to be a problem: this file contains in variable A$ the source code for an assembler file (for ASDIS). The basic program contains only REM. If the program is loaded e. g. by EO and ZX81.rom and I press RETURN, the listing is written to screen and the Zeddy is alive. If the program is l...
by siggi
Mon Apr 15, 2019 9:15 am
Forum: ZX BASIC
Topic: MC INKEY$ replacement
Replies: 2
Views: 568

Re: MC INKEY$ replacement

Hi Greg this is not a real "inkey" function like in BASIC. The BASIC inkey$ function reads the keyboard "on the fly" and does not wait for a key to be pressed. But this mc stays inside a loop (and does not return) if no key is pressed: @Again Call Keyboard ;Call ROM scan keybd. INC L ;Check for no k...
by siggi
Fri Apr 12, 2019 10:28 am
Forum: Development
Topic: How to Build a keystick port internally to zx81
Replies: 5
Views: 622

Re: How to Build a keystick port internally to zx81

Connecting a joystick directly to the keyboard lines will overload the Z80 addressbus (driving the keyboard lines), because the capacitive load of the long cable to the external joystick is too high. At least some additional components (transistors or driver ICs) are necessary to drive this long cab...
by siggi
Fri Feb 15, 2019 9:51 am
Forum: Hardware
Topic: ZX81 controls a lathe
Replies: 3
Views: 549

Re: ZX81 controls a lathe

Do not know Joachim's "Eiermaler"? If not, here it is..

http://forum.tlienhard.com/phpBB3/viewt ... f=2&t=2278
by siggi
Thu Feb 14, 2019 10:07 am
Forum: Hardware
Topic: ZX81 controls a lathe
Replies: 3
Views: 549

ZX81 controls a lathe

FYI:

Joachim controls his (old and small) lathe with a ZX81:

http://forum.tlienhard.com/phpBB3/viewt ... =2&p=38419

Siggi
by siggi
Fri Dec 07, 2018 10:17 am
Forum: Hardware
Topic: Reversible 16K RAM
Replies: 11
Views: 1628

Re: Reversible 16K RAM

McKlaud wrote:
Thu Dec 06, 2018 11:33 pm
And don't forget about 10k resistor between pins 27 & 28.
.. which is not necessary for this use case ;)

Maybe it has been necessary for ram extensions, which had a battery (to write-protect the ram during power-off state) ...

Siggi
by siggi
Thu Dec 06, 2018 11:16 pm
Forum: Development
Topic: New to Machine code, help required
Replies: 17
Views: 2471

Re: New to Machine code, help required

Also, if you press the CONT key, your first routine will print another screen of characters... Thats because the JR NZ tests the value of the A Register, you are decrementing BC. No, JR NZ tests the Z-flag, which is part of the F register. It could be set by a lot of instructions (like "DEC C" or "...