Search found 3349 matches

by 1024MAK
Tue Jan 19, 2021 11:24 am
Forum: Hardware
Topic: My first ZX80.
Replies: 75
Views: 7151

Re: My first ZX80.

With analogue video signals, because the video signal is rather complex, both in timing and in respect of the different voltage levels, if the signal seen by the monitor is out of specification, the TV or monitor will not display a stable video picture. Because Sinclair used a simple mixer circuit (...
by 1024MAK
Tue Jan 19, 2021 2:18 am
Forum: Hardware
Topic: ZX81 ROMs 3 types?
Replies: 20
Views: 336

Re: ZX81 ROMs 3 types?

Thanks Moggy ;) :D 8-) 622ROM.rom and 649ROM.rom - are definitely different. 622ROM.rom and "zx81 version 2 'improved' rom (Sinclair).rom" - different, same differences as above. 649ROM.rom and "zx81 version 2 'improved' rom (Sinclair).rom" - are the SAME. I think that I got the "zx81 version 2 'imp...
by 1024MAK
Mon Jan 18, 2021 9:22 pm
Forum: Spectrum BASIC
Topic: Decimal Value
Replies: 6
Views: 85

Re: Decimal Value

Folks, I'm probably stupid but I'm actually failing to enter the following command using Spectrum Basic: LET TEST=123456,789 When I hit the ENTER key I get LET TEST=123456,?789L So I'm not able to assign 123456,789 to TEST. Any help is appreciated. ZX81 and ZX Spectrum basic uses a dot/decimal poin...
by 1024MAK
Mon Jan 18, 2021 3:35 pm
Forum: Hardware
Topic: ZX81 ROMs 3 types?
Replies: 20
Views: 336

Re: ZX81 ROMs 3 types?

The next question, is which ROM code is being used in all the emulators? The code from the 622 or the code from the 649? And which code are the disassemblies based on? It’s best not to assume anything. The other thing is, this may just be one or two bytes that are different, or maybe some of the cod...
by 1024MAK
Mon Jan 18, 2021 2:24 pm
Forum: ZX Spectrum Lounge
Topic: New (to me Speccy)
Replies: 2
Views: 73

Re: New (to me Speccy)

In my reply, I’m assuming you are getting a rubber key 16k or 48k ZX Spectrum, or a ZX Spectrum plus. Any 9V DC PSU that has a smooth or regulated output rated at 1.4A or more will do. The really important point though is that you double check the the output polarity is correct. The ZX Spectrum requ...
by 1024MAK
Mon Jan 18, 2021 1:39 am
Forum: Hardware
Topic: ZX81 ROMs 3 types?
Replies: 20
Views: 336

Re: ZX81 ROMs 3 types?

Oh, and these ROMs are SO R@RE that I only had to look at SIX boards before I found one! :lol:
And it’s in a socket :D
ZX81 ROM NEC D2364C 622
ZX81 ROM NEC D2364C 622
ZX81 ROM NEC D2364C 622

Mark
by 1024MAK
Mon Jan 18, 2021 1:13 am
Forum: Hardware
Topic: ZX81 ROMs 3 types?
Replies: 20
Views: 336

Re: ZX81 ROMs 3 types?

I’ll be honest and tell you that I’ve not actually looked into the method that the ZXpand uses to ‘page’ out the internal ROM. Although I know which signal line on the edge-connector it uses, the bit I have not looked into is the circuitry on the ZXpand board itself. Anyway, putting aside the ZXpand...
by 1024MAK
Sun Jan 17, 2021 10:06 pm
Forum: Hardware
Topic: ZX81 ROMs 3 types?
Replies: 20
Views: 336

Re: ZX81 ROMs 3 types?

Now need a binary dump of the last two to see where the differences are...

Mark
by 1024MAK
Sun Jan 17, 2021 1:58 am
Forum: Development
Topic: New ZX80 cases
Replies: 28
Views: 18457

Re: New ZX80 cases

The interest from the Sinclair Computing forum is as follows: ‪atjens (‬Anders) - I would be interested in one case. ‪simmonj‬ (Jeff) - I would be interested in a UK version. ‪DamnedOne‬ - Yes please! I would be interested in 2. [Atlhough you have posted here on Sinclair ZX World as well!] ‪J2112Z‬ ...
by 1024MAK
Sat Jan 16, 2021 9:44 am
Forum: Hardware
Topic: ZX80 machine that shows a cursor but no text
Replies: 6
Views: 249

Re: ZX80 machine that shows a cursor but no text

Yes, see what signal you get on IC9 outputs, pins 7 (/Q) and pin 9 (Q).

if your 'scope is a two channel type, you can try to sync to IC9 pin 1 (S/L) for per character or to SYNC (IC19 pin 6 or R32).

If you are getting an output signal from IC9, next up, is to test IC20 pins 4, 5 and 6.

Mark