Search found 994 matches

by 1024MAK
Sat Sep 26, 2020 11:13 pm
Forum: Hardware
Topic: issue 2 dc dc modification ??
Replies: 1
Views: 59

Re: issue 2 dc dc modification ??

You mean this?

Mark
by 1024MAK
Fri Sep 25, 2020 11:31 pm
Forum: Hardware
Topic: can the upper ram fail because of low amperage
Replies: 5
Views: 151

Re: can the upper ram fail because of low amperage

One question though, after changing the voltage regulator, is the improvement of the -5 supply still necessary? Ask as many questions as you like... I may not answer all of them though :mrgreen: :lol: Changing the 7805 and fitting a Traco Power, Recom or other good DC-DC converter will reduce the h...
by 1024MAK
Fri Sep 25, 2020 1:28 pm
Forum: Hardware
Topic: can the upper ram fail because of low amperage
Replies: 5
Views: 151

Re: can the upper ram fail because of low amperage

Do you think changing the voltage regulator for a TSR 1-2450 would help? Yes, that definitely helps. A modern DC-DC switching converter like a TSR 1-2450 will be better than 80% efficient. Hence the input current from the nominal +9V supply will be significantly less. And because these modern DC-DC...
by 1024MAK
Thu Sep 24, 2020 6:03 pm
Forum: Hardware
Topic: can the upper ram fail because of low amperage
Replies: 5
Views: 151

Re: can the upper ram fail because of low amperage

How much power is needed depends on which issue board you have. Some really do need 700mA of current at around 9V to 10V. Lack of power will not harm the ‘upper’ RAM, but may result in a malfunction. It is strongly recommended that you get a power supply rated at 1A with a DC voltage of between 8V a...
by 1024MAK
Wed Sep 23, 2020 7:55 pm
Forum: Hardware
Topic: Issue 2 with short to GND on MREQ and A10
Replies: 16
Views: 388

Re: Issue 2 with short to GND on MREQ and A10

Well done MrClump, you’ve just brought a Speccy back from the dead 8-)

Now go and use it for fun :D

Mark
by 1024MAK
Wed Sep 23, 2020 6:45 pm
Forum: Hardware
Topic: Spectrum 2+A blinking power issue
Replies: 17
Views: 668

Re: Spectrum 2+A blinking power issue

Well done on getting it working. I’m sure you are both relieved and delighted that you did not give up!

Have fun now :D

Mark
by 1024MAK
Mon Sep 21, 2020 12:01 am
Forum: Hardware
Topic: components prone to fail
Replies: 2
Views: 117

Re: components prone to fail

This is a list of recommended spares: 4116 (or equivalent) DRAM chips rated at 150ns, 4164 (or equivalent) DRAM chips rated at 200ns, ZTX651 or ZTX653 (to replace TR4) Z80A or CMOS version (rated 4MHz or greater) ULA if you can find one (and can afford one) or a ULA replacement, Various electrolytic...
by 1024MAK
Sun Sep 20, 2020 6:28 am
Forum: Other Retro Stuff
Topic: Build your dream computer
Replies: 67
Views: 1373

Re: Build your dream computer

Not being able to reuse code without manual editing was not just a problem with BASIC though. It's the same with the ROM based FORTH that one home computer had. And the the simple filing system (in most home computers, just a simple cassette tape filing system) does not help. Couple that with the si...
by 1024MAK
Sat Sep 19, 2020 10:20 pm
Forum: Hardware
Topic: New build ZX Spectrum 48k?
Replies: 6
Views: 231

Re: New build ZX Spectrum 48k?

The CMOS Z80 is still in production (and is compatible), so the only real difficult items are:
  • The ULA,
  • The DRAM chips
  • The LM1889 colour encoder chip
  • The ‘coil’.
Mark
by 1024MAK
Sat Sep 19, 2020 10:15 pm
Forum: Other Retro Stuff
Topic: Build your dream computer
Replies: 67
Views: 1373

Re: Build your dream computer

Maybe, but the real problem here is that there appears to have been a vacuum with regards to the BASIC language being extended in a formal way. So each and every manufacturer added there own ‘extras’ in their own way... Note that I am not saying that the extras should not have been included. Merely ...