Either by design or by mistake, the NMI handler in the BASIC ROM will result in the Z80 jumping to the reset vector. With a MF1, it should switch out the BASIC ROM (forcing /ROMCS high) and page in its own ROM. Hence during the NMI it's the MF1 ROM that should be in control.
Mark
Search found 5103 matches
- Fri Mar 22, 2024 4:29 pm
- Forum: Hardware
- Topic: how to verify if a multiface 1 is working ??
- Replies: 11
- Views: 512
- Fri Mar 22, 2024 4:25 pm
- Forum: Hardware
- Topic: ZX Spectrum Issue 6a short
- Replies: 17
- Views: 484
Re: ZX Spectrum Issue 6a short
Sounds (!) like you are nearly there with a working machine. Well done
Mark
Mark
- Thu Mar 21, 2024 3:41 pm
- Forum: Hardware
- Topic: ZX Spectrum +2a issue with all expansion cards
- Replies: 6
- Views: 315
Re: ZX Spectrum +2a issue with all expansion cards
Okay.
All those require the machine to page out the internal ROM chips. Do you have any other expansions/interfaces to try, such as a Kempston (or compatible) joystick interface?
Mark
All those require the machine to page out the internal ROM chips. Do you have any other expansions/interfaces to try, such as a Kempston (or compatible) joystick interface?
Mark
- Wed Mar 20, 2024 10:01 pm
- Forum: Hardware
- Topic: Spectrum modded / composite question
- Replies: 19
- Views: 712
Re: Spectrum modded / composite question
Some important things you need to know about the type of Ferranti ULA chips used in Sinclair computers: They use a type of bipolar transistor technology. This is very different to the other large chips used in the ZX Spectrum. The matrix cells (that provide the logic functions) are CML (current mode...
- Wed Mar 20, 2024 7:31 pm
- Forum: Hardware
- Topic: ZX Spectrum +2a issue with all expansion cards
- Replies: 6
- Views: 315
Re: ZX Spectrum +2a issue with all expansion cards
Which expansion cards / interfaces have you tried?
Mark
Mark
- Tue Mar 19, 2024 4:28 pm
- Forum: ZX BASIC
- Topic: Strange integer behaviour
- Replies: 11
- Views: 549
Re: Strange integer behaviour
The internal ROM function that converts a floating point number to a string is almost certainly the same routine that converts it for printing to the screen.
Mark
Mark
- Mon Mar 18, 2024 6:28 pm
- Forum: ZX BASIC
- Topic: The PAUSE Bug Explained
- Replies: 1
- Views: 191
Re: The PAUSE Bug Explained
Thank you
Mark
Mark
- Sat Mar 16, 2024 7:05 pm
- Forum: Hardware
- Topic: opus discovery questions
- Replies: 4
- Views: 228
Re: opus discovery questions
The best source of help with the Opus Discovery is to work your way through the topics over on WoSf . And yes I think you can use a PC 3½ inch disk drive. You will have to change either the internal link, zero ohm link or the cable wiring so that the drive responds to the DS0 signal from the Opus Di...
- Sat Mar 16, 2024 6:01 pm
- Forum: Hardware
- Topic: how to verify if a multiface 1 is working ??
- Replies: 11
- Views: 512
Re: how to verify if a multiface 1 is working ??
Is the /NMI signal getting to the Z80?
Is the multiface paging out the BASIC ROM and enabling it's own EPROM?
Mark
Is the multiface paging out the BASIC ROM and enabling it's own EPROM?
Mark
- Sat Mar 16, 2024 2:40 pm
- Forum: Hardware
- Topic: Atari joystick without ZXpand+
- Replies: 33
- Views: 1068