Hi,
I purchased this Memopak 16k.
It works but I can't combine it with another Memopak 16k (MT09) or the Sinclair Rampak to get 32k.
It's the version with the Hitachi Ram but it misses the Dip-Switches.
Instead only position 4 is switched on by a wire.
Does anybody know this version and how to set the 4 positions to combine this Memopak with another or with the Rampack?
There are two possible modes for using the MEMOPAK 16K: MASTER and SLAVE. The
mode you require depends on which of the possible memory configurations you are
using. The configurations and modes are as follows:
a) MEMOPAK 16K alone (MASTER)
b) MEMOPAK 16K (MASTER) + MEMOPAK 16K (SLAVE)
c) MEMOPAK 16K (MASTER) + SINCLAIR 16K(SLAVE)
d) MEMOPAK 32K (MASTER) + MEMOPAK 16K (SLAVE)
Now, if your MEMOPAK 16K is being used as a MASTER (alone or with a SLAVE pack
attached somewhere behind) then switches 2 and 3 should be ON and switches 1 and 4
should be OFF. This is how the pack should reach you. On the other hand, if your
MEMOPAK 16K is sitting behind a MEMOPAK 32K or another 16K then it should be
switched into SLAVE mode (1 and 4 ON and 2 and 3 OFF). Remember ON is UP. Now you
can join up the power supply to your ZX81.
Xavier ...on the Facebook groupe : "Zx81 France"(fr)
Hi Xavier,
this seems to be the manual of the MT09 Version.
I tried setting the version in question to slave and to use it behind the Memopak MT09 but it didn't work.
What irritates me the most is that the base setting - off off off on - is one of the settings the MT09 wouldn't work at all, so this version seems to have another PRom?
I didn’t work out the content of the PROM, but for ONE version of the 16K Memotech I did reverse engineer the control circuitry. The details are in the attachment in this post.
Note that where one of the signal lines is labelled IN and OUT, that’s because it’s NOT a straight through connection from the female edge-connector (computer side) to the rear edge-connector (where the additional RAM pack would go). It’s this line that remaps the memory area used by the additional RAM pack.
Given that the board you have did not include the DIL/DIP switches, I think it is likely that the PROM may be different.
Hi all,
I soldered now a four Dip-Switch block on to the board and started to test the positions systematically like so:
First position is a "regular" Memopak 16k with the Master-setting "off on on off"
Second is the "unknown" Memopak 16k.
The second Memopak works together with the first one using the configuration "off off on on" which seems to be a Slave-setting which wouldn't work on a "regular" Memopak 16k.
Standby alert 
