I was wondering that pal/ntsc thing also. I searched around and found things that said there are no differences between the TS1000 and ZX81 roms. But I don't know for sure.
TS1000 white screen but no K
Re: TS1000 white screen but no K
Yes that diagram looks about that I did. I am getting A12/A11 off the edge card rather then solder on the main board for now.
I was wondering that pal/ntsc thing also. I searched around and found things that said there are no differences between the TS1000 and ZX81 roms. But I don't know for sure.
I was wondering that pal/ntsc thing also. I searched around and found things that said there are no differences between the TS1000 and ZX81 roms. But I don't know for sure.
Re: TS1000 white screen but no K
You say you're getting A12-A11 from the edge card but are you also making a connection from the raised pin 23 to the socket hole that was occupied by pin 20?
Re: TS1000 white screen but no K
Nope. Those pins are bent out. Sorry for the poor photo.
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1024MAK
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Re: TS1000 white screen but no K
Both versions (the original bugged and the fixed) of the Sinclair ZX81 ROM work in ZX80, ZX81 and TS1000 (and clones that use the same circuit) machines.
In practice, all later ZX81 and probably all TS1000 machines all have the bug fixed ROM, so if you compare a U.K. ZX81 ROM with a TS1000 ROM, you will find that they are byte identical.
The difference between the machine generating a 625 line 50Hz display (often called PAL even though PAL is actually a colour encoding standard) and 525 line 60Hz display (NTSC) is the fitment of resistor R30. It is not fitted for a 625 line 50Hz display. And fitted for a 525 line 60Hz display. The ROM code reads the status of ULA pin 22 (which this resistor connects to) to adjust its timings to the required display standard.
Machines code programs (either loaded from tape/audio sources, or other means, or other ROMs) may, or may not take any notice of the status of this input pin, so may be locked to one TV standard.
Mark
In practice, all later ZX81 and probably all TS1000 machines all have the bug fixed ROM, so if you compare a U.K. ZX81 ROM with a TS1000 ROM, you will find that they are byte identical.
The difference between the machine generating a 625 line 50Hz display (often called PAL even though PAL is actually a colour encoding standard) and 525 line 60Hz display (NTSC) is the fitment of resistor R30. It is not fitted for a 625 line 50Hz display. And fitted for a 525 line 60Hz display. The ROM code reads the status of ULA pin 22 (which this resistor connects to) to adjust its timings to the required display standard.
Machines code programs (either loaded from tape/audio sources, or other means, or other ROMs) may, or may not take any notice of the status of this input pin, so may be locked to one TV standard.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: TS1000 white screen but no K
Thanks Mark for summing that up for me. That was my understanding but it's good to see it confirmed.
The 6116 chips came in today, and... you where right
No change.
I must be getting close since it's drawing the border. I really hope it isn't the ULA.
The winbond W27C512 showed up also. I need to figure out how to wire those in. I think I have to do something with the extra address lines to select the "bank".
The 6116 chips came in today, and... you where right
No change.
I must be getting close since it's drawing the border. I really hope it isn't the ULA.
The winbond W27C512 showed up also. I need to figure out how to wire those in. I think I have to do something with the extra address lines to select the "bank".