Sinclair ZX80 / ZX81 / Z88 Forums

Just to keep you informed, here are the available options for the Hardware: A) PCB only plus programmed GAL without WIZ812MJ module: 13€ including postage A1) PCB only plus programmed GAL plus WIZ812MJ module: 40€ including postage B) Kit without WIZ812MJ module 25€ including postage B1) Kit plus WI...

Moggy wrote:@Paul.

On a zeddy this early I would say with certainty that the ULA is a 2c158.

Hi moggy. I know. I have all three types as spares.
As I am no collector I am ready to help.
If he doesn't care I would advise to use a 2c210.
kind regards Paul

What date code and type is your broken ULA?
I guess you would prefer to have your replacement as accurate as possible?
At least I wouldn't want to replace a 2C184 by a 2C210.
Maybe I can help with the correct replacement.
kind regards Paul

Due to currency breakdown I will no longer sell in £.
If you like to buy from me, please PM me for momentary prices in €.
So simone was the last whose payment in £ was accepted.
kind regards Paul

Just my comment on the power supply.
I use a 9V battery to power my Chinese mic amp. It introduces no noise.
kind regards Paul

I didn't know this hack.
I always use instead.
Works fine

He did, but didn't tell me which option he prefers.

ranma_simon wrote: I've thought to buy the ZXPAND I Heard can dump in Wav format directly via ZX81 ^_^

I'm afraid this is not true. It won't save them as .WAV but in .P format.
kind regards Paul

As the /ROMCS is low for the lower 16K (by the ULA again via a resistor) you will also need to pull this high in case of 8-16K RAM. Otherwise ROM and RAM will both be active. Maybe you look at a 56K internal RAM schematic for seeing how it's done. http://forum.tlienhard.com/phpBB3/viewtopic.php?f=2&...

The ULA generates ram CS. This is connected to a resistor. The other side of the resistor is connected to ram and the edge connector. By connecting this edgeconnector signal to 5V internal ram is disabled.