29 Sep
2026
29 Sep
'26
8:26 p.m.
On Tue, Sep 29, 2026 at 03:18:43PM -0400, Paul Koning via cctalk wrote:
ENIAC was 40 bits I think.
To a first approximation... :)
Each accumulator operated on a number stored as 10 decimal digits
(each in a ring counter) plus a sign. In pure binary, this would
be equivalent to a little over 34 bits. Data read from cards was
staged in relays before being transmitted to accumulators. There
each digit was stored on 4 relays (but not in BCD). So for a
10-digit number taken from the cards, there were 41 relays (40
for the digits and 1 for the sign) storing it. (Card data could
also be treated as 5-digit numbers.) Around '52 or '53, they
added a core memory unit. I haven't dug into it as much as the
rest of the machine, but I'm pretty sure numbers were stored in
it in essentially the same format as the relays holding card data.
So while calculation and transmission didn't take place in that
format, there were places where numbers were represented with
41 bits.
BLS