Sinclair ZX80 / ZX81 / Z88 Forums

My earlier attempt at collating ZX81 IO port information is here

Mark

@shadow338 Yes, if you do not want the Kempston joystick port, leave out U5, U6, D1, D2 and J2. How we hook up the AUDIO out of the AY to the harlequin original speaker or/and original EAR? In an ideal world, you would use some resistors to form a simple mixer that feeds into an amplifier. One set o...

Once I know the price I will make a first batch of 100 ULAs (if I can afford to prepay all this). I wouldn't mind to prepay my ULA order and think other members would support your job this way, too. ;) Agreed. Paul, I would be happy to pay you in advance (or a contribution towards the final cost) i...

thanks Mark, the last post in your thread shows the Tracopower not much taller than the socket next to it so I'll try a test fit before soldering it in place to see if it's nessasary to install it on its side. @Tezz, yeah, I have not tried a Tracopower in a ZX81 yet. So even I don't know :lol: Mark

@Paul - that's looking like some great work

Mark

BTW.. on an unrelated topic, that board has a Recom DC converter installed, will it still fit in the case or does it stand too proud of the board? I was intending to install a Tracopower on the board but that one might be a little too tall to fit? Have a read of this thread ;) Also have a look at t...

Mark

Mine has a 220pF for C15, as does another ZX80 that I am repairing. In practice, it may be that the value is selected depending on the type of 6.5 MHz resonator fitted (X1). CMOS Z80s will be at risk from static discharge. NMOS chips can also be killed by static. Be very careful when probing about, ...

As for Yamaha "improving" the analogue outputs I can only assume,as you didn't go into any detail, that you mean bigger out-put voltages/currents. In practice I have always found my AY to be the better driver of an amplifier, when inserted separately into any stereo set-up my AY plays any common tu...

I also said conditioning was needed but my post was deemed long winded so will answer this problem from now on by email, anyway by what means are the channel out-puts connected to the stereo socket? The schematic doesn't make it clear. (I'm sure you've posted this schem' before then said whoops wro...