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by tzok
Fri Jan 01, 2021 11:34 pm
Forum: ELECTRONICS
Topic: Voltera printer - the beginning..
Replies: 60
Views: 28023

Re: Voltera printer - the beginning..

You are selling these, so I guess you have to use lead-free, to be RoHS compliant. But for prototyping, try leaded. It flows much better, and in lower temperatures. If something goes wrong, you can reflow it, even without adding flux. It also requires much less precision while applying it on the PCB...
by tzok
Fri Jan 01, 2021 7:41 pm
Forum: ELECTRONICS
Topic: Voltera printer - the beginning..
Replies: 60
Views: 28023

Re: Voltera printer - the beginning..

Are you using leaded or lead free soldering paste. From my (small) experience leaded on is much easier to work with.
by tzok
Wed Dec 23, 2020 2:06 pm
Forum: 8 BIT CORNER
Topic: A little bit of 8 Bit: 65XE upgrade to 128k RAM
Replies: 65
Views: 39862

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Have you tested base RAM with something more than a SELF-TEST? MT chips are known to go bad.

Interesting - you have 3 different types of capacitors in RAM BANK 1, and some sockets are rotated by 180°.

Sally (6502C) normally gets quite hot, but it also gets damaged quite often, worth to check.
by tzok
Tue Dec 22, 2020 2:13 pm
Forum: 8 BIT CORNER
Topic: A little bit of 8 Bit: 65XE upgrade to 128k RAM
Replies: 65
Views: 39862

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Not MMU, but EMMU. This is how 130XE (ECI) boards were configured for 65XE/800XE computers.

You could also replace the MMU, with another one or a programmed GAL replacement.
by tzok
Mon Dec 21, 2020 2:18 pm
Forum: 8 BIT CORNER
Topic: A little bit of 8 Bit: 65XE upgrade to 128k RAM
Replies: 65
Views: 39862

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

These "resistors" mounted instead of EMMU are just jumpers (0 Ohm).
by tzok
Sun Dec 20, 2020 12:34 pm
Forum: 8 BIT CORNER
Topic: A little bit of 8 Bit: 65XE upgrade to 128k RAM
Replies: 65
Views: 39862

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Try to remove EMMU and cross-wire its socket, so the computer would behave as it had only 64 kB of RAM, and if it doesn't help, try to substitute MMU with another one or a GAL replacement (in 800 XL it was a PAL chip, so GAL replacement is 100% compatible).
EMMU_64k.png
EMMU_64k.png (212.64 KiB) Viewed 3673 times
by tzok
Sat Dec 19, 2020 3:29 pm
Forum: 8 BIT CORNER
Topic: A little bit of 8 Bit: 65XE upgrade to 128k RAM
Replies: 65
Views: 39862

Re: A little bit of 8 Bit: 65XE upgrade to 128k RAM

Ok, I own any TMS4164-15NL, are they compatible with the first bank (42164-15) ? By markings, they are ok, but these chips look suspicious to me. Like they were sanded and re-engraved. Do they come from Aliexpress? I had similar glitches in my 800XL, and it was a faulty ANTIC chip (it was working c...
by tzok
Wed Dec 16, 2020 10:14 am
Forum: ELECTRONICS
Topic: 4 channel scope recommendations ?
Replies: 19
Views: 6246

Re: 4 channel scope recommendations ?

If you want to observe just repetitive analog signals, then time equivalent sampling is ok, but if you want to catch a glitch in a digital signal, that occurs once in a few thousands (or more) cycles, then deep memory, and high real time sampling are crucial things to have. This old HP is just "...
by tzok
Tue Dec 15, 2020 10:35 pm
Forum: ELECTRONICS
Topic: 4 channel scope recommendations ?
Replies: 19
Views: 6246

Re: 4 channel scope recommendations ?

I remember those HP scopes from school, but for today's standards 54602B really isn't impressive. It is only 20 MSa/s, and for most time is working in time equivalent sampling. Its effective bandwidth for real time sampling is about 5 MHz, and has almost no memory (just 4 kPts). The entry level mode...

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