Owner of the one pictured: Edward Hammond
Donor of Tom's: James (Jimbo)
I finally managed to luck into one of these, direct
from England. Mine as an added chiclet keyboard that
looks great. There are new pictures below, but they
didn't turn out very sharp.
Edward Hammond Comments:
As I recall, I got this computer when I was 12. That
would make it 1980. Does that sound right? It was my
first, and it was a little intimidating at the start.
Although I eventually learned how to do OK with the ZX-81
BASIC, I initially limited myself to
"annoy-your-siblings" programs. It went sort of
10 FOR X=1 TO 500
20 PRINT "Elizabeth is a Lizardbreath"
30 NEXT X
About the time I started to get really good at this
and delve into the expanded capability of the 16k RAM
module (the ZX-81 has only 1k of on-board RAM), I was
distracted by high school, Apple II's and later Macs.
Now, I mainly work on a PPC 8500/120.
Technical Specifications: (taken directly from the
Depth: 167 mm (6.32 in)
Height: 40 mm (1.57 in)
Weight: 350 grams (12.15 oz)
CPU: Z80Z at 3.25 MHz
ROM: Containing 8k BASIC interpreter
RAM: 1K byte internal, externally expandable to
Other Spec's (summarized from Supplement):
40 key, w/ graphics and function modes, includes
20 graphical and 54 inverse video characters
Sinclair calls the keyboard a "touch
24 lines x 32 characters (text)
64 x 44 pixels in graphics mode
FAST and SLOW modes. In SLOW mode, "the ZX81
will both compute and display
simultaneously." In FAST mode, you go 4
times faster, but the display is delayed and
"Programs and data can be saved onto the
cassette [not provided] so that they are not lost
when the ZX81 is turned off." Transfer rate
to and from the cassette recorder is 250 baud.
"Numbers are stored in 5 bytes in
floating-point binary form... accurate to 9 1/2
Requires 420ma at 7-11V DC. This is the only
piece of the original package I have lost.