Memory Expansion Modules
|Collectors frequently sell old Sinclair products
Click the "GO" button on the left to find any Sinclair
joysticks being auctioned.
|| sinclair (zx80,zx81) (pack,rampack,memory) -(timex,calculator,power)
info on buying & selling Sinclair computers
Sinclair's memory expansion
module, more commonly called a RAM pack, was simply a box
with extra memory chips which plugged into the back of a ZX80
to expand the otherwise pitifully small memories of the two
computers. A 3K RAM pack (above left) was available
for the ZX80, with a 16K model (above right) available
for the ZX81. The standard 16K RAM packs were produced by
Sinclair, but other manufacturers produced them in larger
sizes, up to an improbable 128K. The ZX81's 16K RAM pack was
rebadged in the US as the TS
1016, for use with the TS
1000 (which was itself a rebadged ZX81).
Unfortunately, the Sinclair
RAM packs suffered from a major design flaw. They plugged
into the edge connectors of the first two ZX computers, but
were otherwise physically unsupported. This meant that the
slightest nudge could incur the dreaded "RAM pack wobble",
when the circuit with the computer was briefly interrupted.
At best, this meant that any data in memory would be lost.
At worst, it could blow the computer's circuit board. Hence
many Sinclair users found that a piece of sticky tape or bubble
gum was an essential accessory, used
to keep the RAM pack in place. Other manufacturers produced
more reliable alternatives, designed to rest flush with the
table top and the back of the computer (a good example is
Memotech's popular offering, right).
Spectrum could be expanded
internally with a kit available from Sinclair Research,
so no official RAM pack was produced, although a few third-party
manufactures offered external expansion modules.
© Chris Owen 1994-2003