Search found 2766 matches

by Dave
Tue Apr 09, 2024 11:10 pm
Forum: Prospective Members
Topic: Alas...
Replies: 0
Views: 42

Alas...

I think we can lay this one to rest now.
by Dave
Tue Apr 09, 2024 10:35 pm
Forum: Hardware
Topic: Switching Regulator?
Replies: 37
Views: 2166

Re: Switching Regulator?

Interesting conversation to catch up on. 7805 is a very inefficient analog regulator and that inefficiency comes out as heat. Often 60-70% efficient, depending on the input/output voltage. Buck regulators are switching 'digital' regulators [1] that make a lot of switching noise but are very efficien...
by Dave
Tue Apr 09, 2024 9:56 pm
Forum: Hardware
Topic: Serial port confusion.
Replies: 18
Views: 3751

Re: Serial port confusion.

Actually, Sinclair's solution was a good idea of having a DTE and a DCE configured serial port because it avoids having an external NULL modem gender changer because the conversion is builtin to the QL. They made up for it with the bad idea that received information from both sockets goes to a sing...
by Dave
Tue Apr 09, 2024 9:52 pm
Forum: Hardware
Topic: FPGA replacment for the ZX8301 ULA and more
Replies: 254
Views: 98867

Re: FPGA replacment for the ZX8301 ULA and more

Yeah, those red sockets are junk. I have had to replace dozens of them as they often fall apart if the CPU is stuck in them. Any time I installed an internal memory expansion in a QL at Sandy and it had a red socket, I'd fire up the weller first just in case. On my multitude of QLs, if I see a red s...
by Dave
Tue Apr 09, 2024 9:13 pm
Forum: Hardware
Topic: PiStorm
Replies: 114
Views: 20782

Re: PiStorm

The PiStorm signal transitions are incredibly quick, and play absolute mayhem with the QL. The PiStorm can function in a Gold Card if the onboard DRAM is removed and the refresh signal used by INGOT is inhibited. However, external signals would need conditioning to reduce their slew rate. The SGC cl...
by Dave
Tue Apr 09, 2024 9:06 pm
Forum: Hardware
Topic: USB Keyboard IF
Replies: 38
Views: 8161

Re: USB Keyboard IF

Also its a mystery that the QL has a 9x11 Matrix, the 8049 IPC only supports 8x8 Matrix. The CTRL, ALT and SHIFT keys are on their own line separate from any other keys, so pressing them and two other keys does not create a ghost click on the 4th corner. This adds one line on one axis of the table ...
by Dave
Tue Apr 09, 2024 8:46 pm
Forum: Hardware
Topic: 4864 DRAM
Replies: 3
Views: 197

Re: 4864 DRAM

The RAM in the QL was the absolute least they could get away with. Everything is marginal. With the incredibly poor power and debounce practices used, the QL seems to spend almost all its life only just working. Some early FB QLs had -200 DRAM, but they quickly switched to -150 and some of the very ...
by Dave
Tue Apr 09, 2024 7:41 pm
Forum: Hardware
Topic: FPGA replacment for the ZX8301 ULA and more
Replies: 254
Views: 98867

Re: FPGA replacment for the ZX8301 ULA and more

I looked at this project on Hackaday and it is quite interesting. On the buffer, it would help to connect all unused inputs to ground or +5V. Between the buffer and the monitor connected pins of the 8301 socket, it would offer extra protection to add 5.1V zener diodes to ground. Apart from that, eve...
by Dave
Wed Sep 13, 2023 7:34 pm
Forum: Hardware
Topic: ql printer printhead search
Replies: 5
Views: 777

Re: ql printer printhead search

The SP800 head is compatible. The flex PCB ribbon is slightly different on some revisions but it is easy to swap them with a soldering and middle school soldering skills. The SP1000 head also works, but the ribbon is longer and always needs swapping. So if you check your flex ribbon is OK before ord...
by Dave
Wed Sep 13, 2023 7:27 pm
Forum: For Sale
Topic: ROM, 512k RAM, felt pads + VGA
Replies: 27
Views: 24302

Re: ROM, 512k RAM, felt pads + VGA

It will work if you’re using any ROM except JSU.