Search found 2482 matches

by 1024MAK
Thu Oct 17, 2019 9:18 pm
Forum: ZX Spectrum Lounge
Topic: Problem with Grey +2
Replies: 9
Views: 126

Re: Problem with Grey +2

I suspect that maybe one of the multiplexer chips is misbehaving. But before I continue speculating, do you have a multimeter, and have you tested the +5V supply and +9V supply rails? The long chip with the heatsink is the ULA. And no, it is NOT the same type as used in the 48k. How long (approximat...
by 1024MAK
Thu Oct 17, 2019 12:15 am
Forum: Hardware
Topic: Non working ZX81
Replies: 28
Views: 1038

Re: Non working ZX81

A post with a useful collection of pin outs (including Z80, ULA, ROM, RAM) for ZX81s is linked to in my sig. below...

Mark
by 1024MAK
Wed Oct 16, 2019 12:24 am
Forum: Hardware
Topic: ZXpand and the ZXpand-AY Sound Module wobble?
Replies: 4
Views: 153

Re: ZXpand and the ZXpand-AY Sound Module wobble?

Can you see the wings of fly moving in real time with your eyes? The answer is no. With any mechanical connector where movement is possible, like the expansion port edge-connector, it is possible for movement to cause one or more of the contacts to momentarily break for a very short time. Far too br...
by 1024MAK
Mon Oct 14, 2019 11:09 pm
Forum: Hardware
Topic: Non working ZX81
Replies: 28
Views: 1038

Re: Non working ZX81

I guess not then. Ok, no worries. I'll figure something out. Sorry, I’m rather busy at the moment (work). I got up at 07:00 this morning for a meeting in city far from home. And have just got on the train home. I’m also rather busy for the rest of the week. If you don’t have an answer by the weeken...
by 1024MAK
Mon Oct 14, 2019 5:31 pm
Forum: ZX BASIC
Topic: is there an updated zx81 rom?
Replies: 6
Views: 239

Re: is there an updated zx81 rom?

the7778 wrote:
Mon Oct 14, 2019 5:21 pm
i noticed the zx97 rom in there, will this work with an emulator?
Only with emulators that were designed to work with it. The ZX81 normal ROMs are 8K bytes in size, the ZX97 ROM is much larger.

Mark
by 1024MAK
Mon Oct 14, 2019 5:06 pm
Forum: ZX BASIC
Topic: is there an updated zx81 rom?
Replies: 6
Views: 239

Re: is there an updated zx81 rom?

There were only two official versions (the first one “standard” having a bug, replaced with the “improved” ROM).

There have been a number of third party replacements that do things differently, often just further bug fixes.
This site has some...

Mark
by 1024MAK
Sun Oct 13, 2019 3:02 pm
Forum: Welcome Area
Topic: Hello from Nottingham, UK.
Replies: 21
Views: 442

Re: Hello from Nottingham, UK.

Hello and welcome to our forum Graham!

:D :D :D

I hope you enjoy the forum :D

We are happy to help if you have any questions.

Mark
by 1024MAK
Thu Oct 10, 2019 4:15 pm
Forum: Welcome Area
Topic: Hi from South-Africa
Replies: 1
Views: 170

Re: Hi from South-Africa

Hi Albertus

Welcome to our forum :D

You had me confused, as I was thinking, we have someone already here with a user name that is very similar :lol:

Have fun :mrgreen:

Mark
by 1024MAK
Thu Oct 10, 2019 4:09 pm
Forum: Hardware
Topic: Hack to get 5V for keyboard
Replies: 15
Views: 539

Re: Hack to get 5V for keyboard

Sorry, I should have said. Multilateral ceramic capacitors are not polarised, so you will have to change the symbol / type. The only reason that some types of capacitor are polarised, is due to the limitations of the practical construction of the capacitor. In any circuit, if there is an equivalent ...
by 1024MAK
Thu Oct 10, 2019 3:27 pm
Forum: Hardware
Topic: Hack to get 5V for keyboard
Replies: 15
Views: 539

Re: Hack to get 5V for keyboard

Enter part number CL05A475MP5NRNC in the search box at this link . This capacitor may be a suitable SMD multilayer 4.7uF capacitor. I’ve not fully checked the specs, as I’m on a train... but the capacity and voltage rating should be okay. Mark Note: edited, as the original link was not very helpful :(