Sinclair ZX80 / ZX81 / Z88 Forums

220nF would be sufficient. This is not an issue with the capcistance only. In this application the main factor is ability to fast charging and discharging of these caps. So, the ESR would play the main role.

Jupiter ACE is not popular like ZX81. Please bear in mind that there was sold no more 10,000 units of Jupiter ACE in 80-ties. A few more replica PCBs in recent years do not make any difference. I would not be surprised if SirMorris said 'no'. Regarding the memory map, the partial address decoding of...

Jupiter ACE memory map can be found there: http://k1.spdns.de/Vintage/Sinclair/80/ ... memory.txt

Please note that the 8K ROM is full. You can use larger EPROM chip but the address deciding is simplified and you will not gain much. The new address decoder is needed.

dessony : have a look into the Jupiter's memory map. It looks like a Swiss cheese :lol: due to a partial address decoding. Any user memory extension can sit between 0x4000h and 0xFFFF addresses. So, the easiest way to extend the user memory from 1K to 17K (+16K) is employing any 16K RAMpack for ZX8...

I've been thinking about re-designing the PCB completely and make Jupiter in the ZX Speccy format, using newer components like 6116 SRAM chips instead of 2114, but this is a long shot.

So sorry, I would not publish Gerbers or source files for the main PCB on any public website. I am not going to order another batch of these boards in near future, because I am busy with a few bits and bobs for my Jupiter. I should publish on there detailed photos how I made the keyboard useful. I h...

Hi Alex,

Good you joined us.

Kind regards

unxiax: I’ve got a few boards left and not planning for any new batch.

The keyboard overlay that I printed on a self adhesive vinyl sheet and than sticked to the 1.0mm PCB overlay. I can share the Gerber files for it and you can order a small batch of them by yourself if you wish.

HullZX81man: Hi, PM sent.