Sinclair ZX80 / ZX81 / Z88 Forums

A check reveals that as Kmurta says the older EPROM (V 5.1 in this example ) doesn't possess the necessary hooks usable by commander. Ignore the inverse screen as that's how I run my zeddies and has nothing to do with your problem. EPROM updates here... https://www.sinclairzxworld.com/viewtopic.php?...

I do have an Issue 2 Zeddy. Really!? What kmurta is referring to is the EPROM issue number on the spand which should be at least 6.6 if memory serves as v5.1 may not have the entry vectors he refers to. If that is the case you may have to re-flash the EPROM with v6.6 and if not able to do yourself ...

Try saving it as a P file rather than TZX.

That makes sense,Mark.

Bit by bit I think we'll get there.

Full text of post which is all I can go by so make of it what you will. Quote. "A bigger capacitor and smaller resistor would simply increase the output voltage even more! Since a magazine suggests it, seems that someone has already tried it and it *should* be safe for the Zeddy! But as the 50mV see...

1024MAK wrote: ↑Sun Apr 04, 2021 6:12 pm The existing R33 should already be 4.7kΩ...

C12 and R29 are part of the Mic circuit.

Mark

Hmmm, the magazine was incorrect then?

The thread concerned was about increasing the output of the MIC socket but someone did ask about making the ear socket more sensitive and this answer was posted... "An old issue of "EchosSinclair" suggests 100pF for C12, 470Kohm for R29 and 4,7Kohm for R33 (to increase the EAR jack sensitivity)" I d...

I,m sure someone on the German forum actually did something similar but posted it on here,I will have a look to see if I can find it.

There is something you can do to increase the output of the 386,if it hasn't been done already by the makers and will take a bit of confidence on your part to try. Like most op-amps used for audio they rely on a bias circuit to control the strength of the out-put. The 386 is a bit unusual in that it...

All the ROMs could be classed as bugged as they still have the rounding errors inherent in floating point maths. There was a couple of articles by maths guru Frank O'Hara in ZX computing that explained this in great depth along with work-arounds in BASIC. Internally the ZX81 is accurate to 9.5 digit...