There is most definitely a help or example file somewhere, I've seen it. I just can't remember where...
Mark
Search found 5122 matches
- Fri Mar 15, 2024 10:31 pm
- Forum: Software
- Topic: ZXpand+ JOYCFG.TXT file
- Replies: 7
- Views: 1408
- Fri Mar 15, 2024 9:20 pm
- Forum: Software
- Topic: ZXpand+ JOYCFG.TXT file
- Replies: 7
- Views: 1408
- Fri Mar 15, 2024 9:16 pm
- Forum: Hardware
- Topic: ZX Spectrum Issue 6a short
- Replies: 17
- Views: 3451
Re: ZX Spectrum Issue 6a short
The ULA only runs off the +5V. And indeed, the actual supply to the core goes via resistor R34 to pin 13. The ULA has no direct connections to the -5V or +12V supplies. ULA pin 14 just supplies the peripheral interface circuitry. The normal cause of problems with the -5V or +12V supplies, TR4 cookin...
- Fri Mar 15, 2024 8:43 pm
- Forum: Hardware
- Topic: Spectrum modded / composite question
- Replies: 20
- Views: 2458
Re: Spectrum modded / composite question
Well, with only seven 4116 DRAM chips fitted, it will do something, but no, it will not run BASIC.
The ULA should however produce a picture. What you get depends on which chip is missing. The effect being different depending on which one it is that is missing.
Mark
The ULA should however produce a picture. What you get depends on which chip is missing. The effect being different depending on which one it is that is missing.
Mark
- Fri Mar 15, 2024 1:37 pm
- Forum: Hardware
- Topic: Atari joystick without ZXpand+
- Replies: 33
- Views: 3660
Re: Atari joystick without ZXpand+
BASIC always uses its own ROM routines to read the keyboard. At the lowest level, this is the Z80 processor using the Z80 machine code IN instruction. Each keyboard half row has its own I/O address. The data returned is one byte, but only five bits are keyboard data. Hence it takes eight IN instruct...
- Thu Mar 14, 2024 5:04 pm
- Forum: Hardware
- Topic: Atari joystick without ZXpand+
- Replies: 33
- Views: 3660
Re: Atari joystick without ZXpand+
I was looking at the schematic and wondering how external keyboards work via the edge connector if there is no access to the five KBD lines that go to the ULA. Is the ROM checking for keypresses? I haven't yet tripped over how this actually works yet. That's an entirely new subject... The simple an...
- Thu Mar 14, 2024 4:56 pm
- Forum: Hardware
- Topic: Atari joystick without ZXpand+
- Replies: 33
- Views: 3660
- Thu Mar 14, 2024 4:53 pm
- Forum: Hardware
- Topic: Atari joystick without ZXpand+
- Replies: 33
- Views: 3660
- Thu Mar 14, 2024 3:31 pm
- Forum: Hardware
- Topic: Atari joystick without ZXpand+
- Replies: 33
- Views: 3660
Re: Atari joystick without ZXpand+
There was no particular joystick interface that was popular for the ZX81, hence there is no real "standard". Just various interfaces that don't have much in the way of software support, most of which were forgotten about long ago. Kempston produced joystick interfaces for the ZX Spectrum, but used t...
- Wed Mar 13, 2024 7:32 pm
- Forum: Hardware
- Topic: Spectrum modded / composite question
- Replies: 20
- Views: 2458
Re: Spectrum modded / composite question
These days, it's whatever you can get hold of that work. And yes, you can mix and match. Sinclair used various makes/brands of 4116 DRAM or equivalents. Alternately, use 4164 type and modify the board to suit these. Whatever you use, they do need to have an access time of 150ns or faster. Slower par...