Sometimes I also get a black square then this
Typing at this point seems to do nothing.
So, I really am guessing memory. It happened..
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- Location: San Francisco
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- Posts: 122
- Joined: Wed Apr 08, 2020 4:48 am
- Location: San Francisco
Re: It happened..
Okay. It turns out the keyboard membrane may just be bad.
I removed the keyboard and used a jumper wire to "type" by connect between the two headers. Once I did this I got the inverted K and was even able to write a little program (PRINT 1 <ENTER>)
So, I know the headers are good, the Z80 is good, the ULA is good, and the ROM is good.
One thing that worries me is that the leads in the keyboard membrane look scorched.
The tips that connect to the headers are black, and part of the wires look annealed
I removed the keyboard and used a jumper wire to "type" by connect between the two headers. Once I did this I got the inverted K and was even able to write a little program (PRINT 1 <ENTER>)
So, I know the headers are good, the Z80 is good, the ULA is good, and the ROM is good.
One thing that worries me is that the leads in the keyboard membrane look scorched.
The tips that connect to the headers are black, and part of the wires look annealed
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- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: It happened..
I have seen that effect in keyboard membranes a few times in otherwise fine computers.
From ZX81s:
From ZX81s:
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA