Sinclair ZX80 / ZX81 / Z88 Forums

Hi,
Found this wiring diagram: I tried to rebuild it:

Kicad project(Schem Editor): The A14 data pin is note A14in & A14out.
Both pins are fitted on the same BUS, or the connector break the A14 line ?

ZX81 BUS A14in ->>CARD->>A14out to other cards ?

If I remember correctly, A14 is split. The A14 line from the ZX81 side of the edge-connector DOES NOT go straight through to the expansion side of the connector, but goes via the logic circuitry. Hence the naming that I used, A14in and A14out. With A14out then feeding any further RAM packs. This allows the Memotech RAM pack to remap the RAM pack connected to its rear connector to a different area of memory.

Mark

Thanks Mark,
May be the MASTER/SLAVE config in the manual ! This card drive the A14 address line, after the card connector.( @$4000/16384 memory segment)
The next memory segment is A16 (@$8000)
Or if A14=0, the 16k segment is $0000-$4000...

Thanks again Mark, it was you circuit diagram !
https://www.sinclairzxworld.com/viewtop ... 9215#p9215

Released 1.0 (config adds): http://zx81.ordi5.free.fr/memotech/MT09_16k/

I have a picture of a partially disassembled Memotech 16K Memopak, it's awaiting some parts and time.
Doesn't look anything like the wiring diagram.
I should be able to dump the PROM, I'll post back if any interest.

There are at least two very different versions, that's why...
The one in your photo uses Hitachi HM4816AP single 5V supply 16K bit DRAM (like used in Acorn BBC Micros). Whereas mine (the hand drawn diagram in the first post that is also on here elsewhere, see this topic) uses 4116 DRAM chips.

Mark

This is the other Memotech 16k pack Mark mentions. Ignore the messy recapping as it's all I had to hand at the time.
Board type MT.09-0.2 The other board being MT05 01


Click on image to enlarge.

Hi,

The MT09 is a 16 RAMPAK.
The MT05 is a 32K RAMPAK.

Don't know if MEMOTECH turn there MT05 in MT09 using 16k RAM ships (cheaper at the time) to sold the MT05 spare PCB.
sP1d3r's PCB is a 32k board! (MT05), 2 rows of HM4816 (16kx1bit). Only one row give a 16k RAMPACK.

I haven't photos from the MT04(???) 64k RAMPACK ! on find on the web.

Memotech used the same boards for at least two other modules.

The MT11-02 MemoText Word processor shares the same MT11-02 board as the Z80 assembler just slightly different components and ROM code.

Moggy wrote: ↑Tue Jul 30, 2024 9:50 pm Memotech used the same boards for at least two other modules.

The MT11-02 MemoText Word processor shares the same MT11-02 board as the word Processor just slightly different components and ROM code.

The Word Processor uses the same board as the Word Processor?