April 1, 1972: Write Only Memory

Embedded Geek writes "While digging around Jack Ganssle's site, I came across an amusing prank from days gone by. In 1972 Signetics recognized April Fools day by printing a full color datasheet (scanned sheet 1 and sheet 2 here) for a Write-Only Memory (which accepts data but never reads it back), a considerable effort when documents were made via literal "cut and paste". Packed with jokes both obvious (a graph of "number of pins left versus number of insertions") and subtle ("Vdd = 0V +/- 2%") it's worth a chuckle."

Comments

There are a few applications for write-only memory

[JaredOfEuropa]

There are circuits in use that are essentially a write-only memory like this (but without the need for a 6 foot fan!), combined with a comparator and possibly a one-way encrypter. You can store an encrypted password in there, which then can never be read back in its encrypted form. Plaintext phrases can be encrypted and compared against the stored password.

One existing application is on debit cards (cards that are charged with a cash amount on the card itself).

Re:This is perfect for my project.

[phil reed]

I get a lot of spam, so I've been working on a hardware accelleration card for /dev/null.

Many years ago, I used to go to DEC Users Group meetings. In the evenings, we'd have "sessions" where the operating system developers would come around and tell war stories. I remember one time that one of the RSX-11 (one of the PDP-11 operating systems) developers was telling us that writes to the Null device (NUL:) was found to be considerable slower than writes to real hardware. Therefore, they had begun development of a null hardware device to be plugged into the system. It was to be called the NUL-11 board, and they had developed quite a bit of specification material for it, unfortunately lost (this was in the early '80s). Very fun stuff.