Editing Shift register (section)

=== Shift register memory ===
Very large [[Shift register#Serial-in serial-out (SISO)|serial-in serial-out]] shift registers (thousands of bits in size) were used in a similar manner to the earlier [[delay-line memory]] in some devices built in the early 1970s. Shift registers don't need many pins or address decoding logic, so was much cheaper than [[random-access memory]] back then.<ref>{{Cite web |last=Shirriff |first=Ken |date=2014 |title=Inside the Intel 1405: die photos of a shift register memory from 1970 |url=http://www.righto.com/2014/12/inside-intel-1405-die-photos-of-shift.html |url-status=live |archive-url=https://web.archive.org/web/20230728203329/https://www.righto.com/2014/12/inside-intel-1405-die-photos-of-shift.html |archive-date=2023-07-28 |access-date=2023-08-06 |website=Ken Shirriff's blog}}</ref> Such ''shift register memory'' was sometimes called ''circulating memory''.

[[Datapoint 3300]], for example, stored its [[Computer terminal|terminal]] display of 25&nbsp;rows of [[Characters per line|72&nbsp;columns]] of 6-bit upper-case characters using 54 200-bit shift registers (arranged in 6 tracks of 9 packs), providing storage for 1800 characters. The shift register design meant that scrolling the terminal display could be accomplished by simply pausing the display output to skip one line of characters.<ref>{{cite web|url=http://bitsavers.org/pdf/datapoint/3300/70116_3300termMaint_Dec76.pdf|website=bitsavers.org|title=DataPoint 3300 Maintenance Manual|publisher=Datapoint Corporation|date=December 1976}}</ref> A similar design was used for the [[Apple I]]'s terminal.<ref>{{Cite web |last=Shirriff |first=Ken |title=Inside the Apple-1's shift-register memory |url=http://www.righto.com/2022/04/inside-apple-1s-shift-register-memory.html |url-status=live |archive-url=https://web.archive.org/web/20230606065258/http://www.righto.com/2022/04/inside-apple-1s-shift-register-memory.html |archive-date=2023-06-06 |access-date=2023-08-04 |website=Ken Shirriff's blog}}</ref>