Search found 1801 matches

by 1024MAK
Wed Dec 13, 2017 7:45 pm
Forum: ZX Spectrum Lounge
Topic: What makes a Sinclair ZX Spectrum Valuable
Replies: 4
Views: 62

Re: What makes a Sinclair ZX Spectrum Valuable

Issue 1 rubber key ZX Spectrums with the light grey keyboard are the only "special" machines, and this is only because not that many were produced. Later machines in really good condition with like new boxes etc also normally fetch good prices. But no, other than that, serial numbers are just number...
by 1024MAK
Wed Dec 13, 2017 5:08 pm
Forum: ZX Spectrum Lounge
Topic: What makes a Sinclair ZX Spectrum Valuable
Replies: 4
Views: 62

Re: What makes a Sinclair ZX Spectrum Valuable

One word: collectors.

Some are so keen to get their hand on "so called" early machines, they can't help themselves and keep bidding. That's assuming that there was plenty of bidders.

If there were only a very small number of bidders, then that may have been a somewhat suspicious sale.

Mark
by 1024MAK
Mon Dec 11, 2017 3:35 am
Forum: Hardware
Topic: Slower than Slow. I mean 25 hertz slow;-)
Replies: 4
Views: 90

Re: Slower than Slow. I mean 25 hertz slow;-)

Keep in mind that any change to the main oscillator frequency will kill the video display, as the ULA and CPU timing comes from this main oscillator. It is the combination of the CPU and ULA working together that generates the video display. The other problem, is that the ULA main oscillator pin is ...
by 1024MAK
Sat Dec 09, 2017 5:02 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2531

Re: ZX81 rebuild

Don't Panic is a phrase on the cover of The Hitchhiker's Guide to the Galaxy... Hence is the standard response to any situation... :lol: Mark Clearly I forgot my towel. Available here and here apparently ;) <Galactic trading rules dictate that Earthlings must trade at their own risk> Have you got a...
by 1024MAK
Fri Dec 08, 2017 11:54 pm
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2531

Re: ZX81 rebuild

Don't Panic is a phrase on the cover of The Hitchhiker's Guide to the Galaxy...
Hence is the standard response to any situation... :lol:

Mark
by 1024MAK
Fri Dec 08, 2017 11:31 am
Forum: Hardware
Topic: Improving Timex/Sinclair Tape Loading
Replies: 60
Views: 2049

Re: Improving Timex/Sinclair Tape Loading

Excellent! Having had some experience of fixing tracks I have broken ( :oops: ) I suspect it will be no problem to sort. 8-) I spy some very close together pads, so it would be a good idea to make sure that any that are not supposed to be connected, aren't actually connected. And yes, soldering a p...
by 1024MAK
Fri Dec 08, 2017 2:07 am
Forum: Sinclair Misc
Topic: Bobs stuff is down
Replies: 5
Views: 235

Re: Bobs stuff is down

https://www.whois.com/whois/bobs-stuff.co.uk
Domain Information
Domain: bobs-stuff.co.uk
Registrar: Namesco Limited [Tag = NAMESCO]
Registration Date: 2006-10-29
Expiration Date: 2017-10-29
Updated Date: 2016-11-16
Status: Renewal required.
*** This registration has been SUSPENDED. ***
Mark
by 1024MAK
Fri Dec 08, 2017 1:53 am
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2531

Re: ZX81 rebuild

Don't Panic!
Just start your fault finding investigation from the start...
  • Test the +5V power rails
  • Check for solder splashes using your eye (and maybe a magnifying glass)
  • Test the Z80 CPU pins, A14, A15 plus /RESET, /MREQ etc...
You'll get there in the end ;)

Mark
by 1024MAK
Wed Dec 06, 2017 6:17 am
Forum: Emulators
Topic: ZX80 Program Listing to text file
Replies: 14
Views: 293

Re: ZX80 Program Listing to text file

Emulators for ZX80

If you use a Unix or similar system, there is also ‪ZEsarUX 6.0 stable‬
viewtopic.php?f=3&t=2675

An old Windows/DOS emulator is NO$ZX by Martin Korth
http://problemkaputt.de/zx.htm

I have not actually tried either in ZX80 mode though.

Mark
by 1024MAK
Wed Dec 06, 2017 12:22 am
Forum: Hardware
Topic: ZX81 rebuild
Replies: 108
Views: 2531

Re: ZX81 rebuild

ZTX313 datasheet http://hardware.speccy.org/datasheet/ztx313.pdf The important bit from the datasheet in this application, is: Max. Storage time (tstg), Max. Turn-off time (toff). For a ZTX313 these are 13ns and 18ns respectively. MPS2369 datasheet http://www.mouser.com/ds/2/308/mps2369-d-1193964.pd...