Search found 5103 matches

by 1024MAK
Fri Mar 22, 2024 4:29 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 ??

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
by 1024MAK
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 :D

Mark
by 1024MAK
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
by 1024MAK
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...
by 1024MAK
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
by 1024MAK
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
by 1024MAK
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 8-)

Mark
by 1024MAK
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...
by 1024MAK
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
by 1024MAK
Sat Mar 16, 2024 2:40 pm
Forum: Hardware
Topic: Atari joystick without ZXpand+
Replies: 33
Views: 1068

Re: Atari joystick without ZXpand+

kmurta wrote: Sat Mar 16, 2024 1:47 pm The Brazilian clones TK82/TK83/TK85 had a joystick input using this scheme. Line A12 is common for keys 6, 7, 8, 0 and line A11 is common for key 5.

The Atari joystick needs to be modified to work in this scheme.
Thank you. That's what I thought.

Mark