The ZX81 uses mode 1 (IM 1) so does not care about what is on the data bus. Hence you don’t need to worry about /M1.
Mark
Search found 5126 matches
- Sat Apr 13, 2024 3:21 am
- Forum: Hardware
- Topic: M1 / printer interface
- Replies: 2
- Views: 1757
- Wed Apr 10, 2024 6:50 pm
- Forum: Hardware
- Topic: ZX81 blank screen
- Replies: 30
- Views: 3916
Re: ZX81 blank screen
Lots get caught out by the UK700 producing 12V to 16V when off load, and 10V to 12V when on load.
Good that you are making progress.
Mark
Good that you are making progress.
Mark
- Tue Apr 09, 2024 9:38 am
- Forum: Welcome Area
- Topic: Mandatory intro post / 6502 Z80 content
- Replies: 4
- Views: 2331
Re: Mandatory intro post / 6502 Z80 content
Hello and welcome to our forum reanimate!
I hope you enjoy this forum
Nice set of 1980s computers and extra hardware
You are welcome to ask questions!
Mark
I hope you enjoy this forum
Nice set of 1980s computers and extra hardware
You are welcome to ask questions!
Mark
- Sat Apr 06, 2024 9:14 am
- Forum: Welcome Area
- Topic: ZX newbie
- Replies: 2
- Views: 813
Re: ZX newbie
Hello and welcome to our forum Staffan!
I hope you enjoy this forum
You are welcome to ask questions!
Mark
I hope you enjoy this forum
You are welcome to ask questions!
Mark
- Fri Apr 05, 2024 12:25 am
- Forum: Hardware
- Topic: Cursor off-screen
- Replies: 9
- Views: 1122
Re: Cursor off-screen
The cursor is not likely to be off-screen, more likely is that the video contrast (voltage) is wrong. Hence the K cursor may be there, just not visible. If the picture size was incorrect, I would expect a rolling image, due to incorrect sync. Keep in mind that the transistor type composite modificat...
- Thu Apr 04, 2024 5:26 pm
- Forum: Hardware
- Topic: how to verify if a multiface 1 is working correct ??
- Replies: 18
- Views: 7091
Re: how to verify if a multiface 1 is working ??
Ahh, I was going to reply the other day, must have forgotten
As the Opus also uses it's own ROM, has the previous owner fitted or modified the MF1 board with a switch or some other method to disable/prevent it's ROM and RAM from being paged in?
Mark
As the Opus also uses it's own ROM, has the previous owner fitted or modified the MF1 board with a switch or some other method to disable/prevent it's ROM and RAM from being paged in?
Mark
- Thu Apr 04, 2024 5:23 pm
- Forum: Welcome Area
- Topic: Thanks for letting me join
- Replies: 3
- Views: 902
Re: Thanks for letting me join
Hello and welcome to our forum Luke!
I hope you enjoy this forum
You are welcome to ask questions!
Mark
I hope you enjoy this forum
You are welcome to ask questions!
Mark
- Tue Apr 02, 2024 5:00 pm
- Forum: SALES
- Topic: Memotech 16K RAM pack - working. £20 plus p&p
- Replies: 8
- Views: 1849
Re: Memotech 16K RAM pack - working. £20 plus p&p
As Moggy says, a PM/DM will sit in your outbox until the recipient reads it. Only then will it move to your sent box.
Mark
- Sun Mar 31, 2024 11:52 am
- Forum: ZX BASIC
- Topic: Forcing an NMI or locking the keyboard via poke command
- Replies: 1
- Views: 1509
Re: Forcing an NMI or locking the keyboard via poke command
You can't force a NMI. A NMI is a non-maskable interrupt which is a hardware signal. Machine code can jump to the address where the NMI routine is, but it's not quite the same. Machine code can HALT the processor, just execute the HALT instruction. But this will not do what you want on a ZX81. I pre...
- Sun Mar 31, 2024 11:38 am
- Forum: Hardware
- Topic: SOLVED !! opus discovery questions
- Replies: 7
- Views: 1816
Re: opus discovery questions
can a " twisted " cable solve this ? Not with a twisted cable designed for PCs, as it will also twist the motor on line, but the Opus only has a single (common to all drives) motor on signal, as it uses a Shugart interface. Shugart interface Floppy Drive Interface Pin Function 2 /DCD Disk Change De...