Search found 562 matches

by 1024MAK
Thu Apr 02, 2020 12:59 pm
Forum: Hardware
Topic: Confusion over Aurora Mouse port numbering
Replies: 5
Views: 145

Re: Confusion over Aurora Mouse port numbering

Keep in mind that conventional D-connectors existed before the idea was thought up of making IDC versions that could connect to IDC cable. Hence the numbering gets a bit confusing. Atari, Amiga, Acorn and some early PC mice are ‘bus’ mice. Two TTL digital lines are encoded with square waves for each...
by 1024MAK
Tue Mar 31, 2020 10:33 am
Forum: Hardware
Topic: QL Add-on ROM
Replies: 34
Views: 1072

Re: QL Add-on ROM

I strongly recommend you do use a resistor to pull up undriven address line inputs. For CMOS chips, a value of between 4.7kΩ and 10kΩ is suitable. If an address line for a CMOS SRAM is allowed to float, it will pick up interface and static charge from other conductors or conductive bodies/objects. A...
by 1024MAK
Tue Mar 31, 2020 9:34 am
Forum: Hardware
Topic: QL Add-on ROM
Replies: 34
Views: 1072

Re: QL Add-on ROM

Dave wrote:You could have a physical witch to connect /WR. If you tie it to 5V it can’t be written. A mechanical pull-up.

I would prefer a wizard, they tend to be more reliable and trustworthy :lol: :lol: :lol:

Mark
by 1024MAK
Sun Mar 29, 2020 3:56 pm
Forum: General QL Chat
Topic: Help with Composite out
Replies: 52
Views: 2362

Re: Help with Composite out

Some questions: ⋅ Am I reading that correctly with regard to SCART going into the two different modes? Some TVs (not many these days) have a user control to select which input system to use on the first (if more than one) or only SCART input. Most automatically switch input mode depending...
by 1024MAK
Sun Mar 29, 2020 3:23 pm
Forum: General QL Chat
Topic: Help with Composite out
Replies: 52
Views: 2362

Re: Help with Composite out

SCART (under a different name) is a product of the French. They passed a law requiring this type of connector to be fitted to all consumer TV/video equipment. It then became popular across Europe. But it has never been popular in the USA. As far as I am aware, nearly all TVs sold in the USA do not h...
by 1024MAK
Mon Jan 27, 2020 2:03 pm
Forum: The Off-Topic Section
Topic: QL vs BBC vs Amstrad 464
Replies: 9
Views: 1120

Re: QL vs BBC vs Amstrad 464

The 6502 CPU used in the BBC Micro only uses the data-bus when the CPU clock is high. Hence if you isolate the address and data lines, the video system can use the time when the CPU clock is low to get screen data from the main RAM. Hence no slowdown. Note that this does not apply if you want your 6...
by 1024MAK
Sat Jan 04, 2020 11:38 am
Forum: For Sale
Topic: Anyone interested in a brand new Sinclair ZX80 case?
Replies: 5
Views: 799

Re: Anyone interested in a brand new Sinclair ZX80 case?

The original cases were vacuum formed. This is where a flat sheet of plastic is heated, then a vacuum pulls the plastic over a mould to form the shape. Any cut-outs that are required then need to be machined out. Injection moulded cases are described by Rick Dickinson in some detail on this page . B...
by 1024MAK
Wed Jan 01, 2020 11:12 am
Forum: For Sale
Topic: Anyone interested in a brand new Sinclair ZX80 case?
Replies: 5
Views: 799

Anyone interested in a brand new Sinclair ZX80 case?

A member of the Sinclair ZX World forum is trying to get a run of brand new Sinclair ZX80 cases manufactured. He says this: I've been working hard recently in getting together different manufacturers in order to produce an EXACT copy of the Sinclair ZX80 case, either the original, or the later injec...
by 1024MAK
Fri Dec 27, 2019 5:24 pm
Forum: Wanted
Topic: Schon keyboard
Replies: 13
Views: 2182

Re: Schon keyboard

These keyboards may have some problems, but then, there are not many keyboards that are over 30 years old that don’t have at least some problems...

Mine (see here) still works okay. Although I don’t use this machine as my regular QL.

Mark
by 1024MAK
Mon Dec 23, 2019 10:29 pm
Forum: Hardware
Topic: Keyboard Interface problem
Replies: 24
Views: 1347

Re: Keyboard Interface problem

Some early AT keyboards had a switch to select XT mode. Of course that won’t help if all you have are PS/2 keyboards... If you search the ‘net you will find that there are three keyboard protocols for the five pin DIN system. It should also be possible to use a microcontroller to carry out a convers...