Search found 2441 matches

by 1024MAK
Fri Aug 30, 2019 10:16 pm
Forum: Hardware
Topic: Improving Timex/Sinclair Tape Loading
Replies: 149
Views: 27927

Re: Improving Timex/Sinclair Tape Loading

Sorry, the delay is 100% my fault :oops: . Far too many distractions coupled with rather a lot going on with my work life.

I’ll go poke myself with a ULA hot soldering iron :shock:

Mark
by 1024MAK
Thu Aug 29, 2019 11:49 am
Forum: FAQs
Topic: why only 1k of ram?
Replies: 2
Views: 826

Re: why only 1k of ram?

Sinclair’s aim with the ZX80, was to produce the lowest cost, but fully functional home computer that was possible. Hence every single part of the design and manufacturing was geared towards this. Apart from the Z80, the ROM chip and the RAM chips, all the remaining chips were inexpensive standard 7...
by 1024MAK
Thu Aug 29, 2019 11:29 am
Forum: FAQs
Topic: Spectrum secret Issue 2 comea with five feet!
Replies: 1
Views: 381

Re: Spectrum secret Issue 2 comea with five feet!

In actual fact issue 3 and onwards boards had two feet inside, one on the modulator and one on the heatsink. The purpose of both was to prevent the keyboard membrane tails from touching the metal of said items. Now after all the intervening years, a lot of these are long gone, and all that is left i...
by 1024MAK
Thu Aug 29, 2019 11:25 am
Forum: FAQs
Topic: What does ULA stand for?
Replies: 2
Views: 419

Re: What does ULA stand for?

Although Sinclair documentation called it the Sinclair logic chip, ULA does mean Uncommitted Logic Array. With these, all the semiconductor structures are already designed and defined by the chip manufacturer. But the final top metal interconnect layer can be designed by the customer (meaning the in...
by 1024MAK
Thu Aug 29, 2019 10:57 am
Forum: Hardware
Topic: Issue 6A weird picture
Replies: 3
Views: 448

Re: Issue 6A weird picture

Gahhh!!! Can’t see the wood for the trees :lol: Thanks Paul :D

So being an issue 6A, at least it has the latest version of the DC/DC converter circuitry.

Mark
by 1024MAK
Thu Aug 29, 2019 6:52 am
Forum: Hardware
Topic: Issue 6A weird picture
Replies: 3
Views: 448

Re: Issue 6A weird picture

Hello and welcome to our forum. It is hard to tell from your photo, is there a border around the central coloured area? This video shows what should happen for a normally working machine. With no lower RAM, the CPU should still be able to execute the start of the ROM code after power up or reset, an...
by 1024MAK
Tue Aug 27, 2019 12:11 pm
Forum: Hardware
Topic: Issue 3 Spectrum 48k no display no boot nothing
Replies: 7
Views: 574

Re: Issue 3 Spectrum 48k no display no boot nothing

Hi ziggy, Good to hear that you are up and running. Sorry about not replying to your earlier post. I must have missed it or got distracted :oops: If anyone else is waiting for a reply, please don’t continually wait, post up a reminder or PM me ;) As you now know, the Z80 won’t do anything useful if ...
by 1024MAK
Fri Aug 23, 2019 5:12 pm
Forum: ZX Spectrum Lounge
Topic: Spectrum 48k Boot pattern
Replies: 26
Views: 1144

Re: Spectrum 48k Boot pattern

I've put the full details of the DC/DC converter modification on my blog here ;)

Mark
by 1024MAK
Fri Aug 23, 2019 4:17 pm
Forum: ZX Spectrum Lounge
Topic: Spectrum 48k Boot pattern
Replies: 26
Views: 1144

Re: Spectrum 48k Boot pattern

-4.3V is correct for that version of the DC/DC converter circuitry. If you want to get it closer to -5V, you have to perform the recommended Sinclair upgrade. I’ll post full details later. But here is a list of parts required: DC-DC CONVERTER MODIFICATION The following new materials are required: Di...
by 1024MAK
Fri Aug 23, 2019 1:50 pm
Forum: Software
Topic: HELP WANTED: ZX81 "lost" files
Replies: 1
Views: 167

HELP WANTED: ZX81 "lost" files

Over on the forum at Spectrum Computing a member is asking for some help with improving the archive of ZX81 software. Here is a copy of that post: Among the data imported from Martijn's WoS years ago, there were thousands of "lost" game files. These are files stored in the archive but not associated...