Search found 1245 matches

by mrtinb
Wed May 18, 2016 9:37 am
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 13764

Re: MIC amplifier

PokeMon wrote:I think mrtinb is more looking for a solution working with original hardware without inside modifications. ;)
Yup :)
by mrtinb
Mon May 16, 2016 10:29 pm
Forum: Hardware
Topic: Creating Wilf Rigter's ZXKBD v3
Replies: 52
Views: 13926

Re: Creating Wilf Rigter's ZXKBD v3

It is finished!

https://youtu.be/ZpxC4x36jlg
image.jpg
(1.02 MiB) Downloaded 371 times
by mrtinb
Fri May 13, 2016 9:07 pm
Forum: Development
Topic: Creating TeleText?
Replies: 17
Views: 3779

Re: Creating TeleText?

dr beep wrote:How often could you 'refresh' the content of the page.

If frequently you can indeed use the settings of teletext as a screen and resolution.
This is not easy reading for me, but seems like a whole tele text screen can be fitted per frame.
by mrtinb
Fri May 13, 2016 1:43 pm
Forum: Development
Topic: Creating TeleText?
Replies: 17
Views: 3779

Re: Creating TeleText?

PokeMon wrote:Second a bit has a duration of 144ns vs. 154ns with the 6.5 MHz resonator in the ZX81. So I think you have to replace the resonator with a 7MHz type (gives 143ns pulses).
Err... the need of a change to the ZX81 almost beats the purpose.
by mrtinb
Fri May 13, 2016 1:01 pm
Forum: Development
Topic: Creating TeleText?
Replies: 17
Views: 3779

Creating TeleText?

Tele text is data sent between picture frames to a TV. Could a custom display routine on the ZX81 create Tele text data, and thereby let the Tele text decoder create the screen? Then the rest of the screen could be used in "FAST mode", because it is not shown on a Tele text decoder. And then the ZX8...
by mrtinb
Fri May 13, 2016 12:47 pm
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 13764

Re: MIC amplifier

Hi :) I'm trying to learn about transistors. Is there any map on the Internet which lists differences between these transistors (so I can see which might be replaced by others), so I would not have to read every single datasheet and make the mapping myself? BC107 BC108 BC109 BC546 BC547 BC548 BC549 ...
by mrtinb
Thu May 12, 2016 11:35 am
Forum: Hardware
Topic: Putting a ZX81 onto a CPLD
Replies: 59
Views: 11884

Re: Putting a ZX81 onto a CPLD

Hasn't this been done already?

http://www.bitcycle.org/retro/zx81/ula/
by mrtinb
Tue May 10, 2016 7:34 am
Forum: Hardware
Topic: Hi-res graphics mode in the ZX81
Replies: 13
Views: 6172

Re: Hi-res graphics mode in the ZX81

I meant:
1024MAK wrote:
mrtinb wrote:If I understand correctly - True Hires is either
  • a memory expansion with Hires capability,
  • a modified memory expansion, or
  • an internal modification addition of RAM circuits.
by mrtinb
Mon May 09, 2016 8:55 pm
Forum: Hardware
Topic: Hi-res graphics mode in the ZX81
Replies: 13
Views: 6172

Re: Hi-res graphics mode in the ZX81

There are several methods of hires. Most common is to create a screen somewhere in memory which is displayed with your own hiresdisplayroutine. There are also hardware interfaces which give you place in memory where you can built UDG and use them as normal characters. If I understand correctly - Tr...
by mrtinb
Sun May 08, 2016 6:41 pm
Forum: Hardware
Topic: MIC amplifier
Replies: 71
Views: 13764

Re: MIC amplifier

mahjongg wrote:you can try implementing the mic pre-amplifier I've built into my ZX81 clone, which is working well.
So the ZX81 connected to the left, and the tape to the right?