DYSEAC

{{Short description|1954 type of computer}}

{{Infobox information appliance

| name = DYSEAC

| aka =

| logo =

| logo caption =

| image = File:DYSEAC van 1.jpg

| caption = DYSEAC van No. 1

| developer =

| manufacturer = National Bureau of Standards for the U.S. Army Signal Corps

| type =

| generation = 1

| release date = {{Start date and age|1954|04}}

| os =

| cpu = 900 vacuum tubes and 24,500 crystal diodes

| CPUspeed =

| memory = 512 words of 45 bits each (plus 1 parity bit)

| RAMtype = mercury delay-line memory

| memory card =

| weight = {{convert|20|ST|MT}}

| predecessor = SEAC

| successor =

}}

File:DYSEAC van 2.jpg

DYSEAC was the second Standards Electronic Automatic Computer. (See SEAC.)

DYSEAC was a first-generation computer built by the National Bureau of Standards for the U.S. Army Signal Corps. It was housed in a truck, making it one of the first movable computers (perhaps the first). It went into operation in April 1954.{{cite journal |date=October 1954 |title=9. Bureau of Standards Computers – DYSEAC |url=https://nsarchive.gwu.edu/document/16909-office-naval-research-physical-sciences |journal=Digital Computer Newsletter |language=en |volume=6 |issue=4 |page=8}}

DYSEAC used 900 vacuum tubes and 24,500 crystal diodes. It had a memory of 512 words of 45 bits each (plus one parity bit), using mercury delay-line memory. Memory access time was 48–384 microseconds. The addition time was 48 microseconds, and the multiplication/division time was 2112 microseconds. These times are excluding the memory-access time, which added up to approximately 1500 microseconds to those times.

DYSEAC may have been the first computer to implement interrupts for I/O.

DYSEAC weighed about {{convert|20|ST|MT}}.{{Cite web |url=http://www.ed-thelen.org/comp-hist/BRL61-d.html#DYSEAC |title=DYSEAC |last=Weik |first=Martin H. |date=March 1961 |website=ed-thelen.org |series=A Third Survey of Domestic Electronic Digital Computing Systems}}