EMB ERJ 145 ER/LR
Flight Crew Air Transport Pilot (ATP)
Workload
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Human Factors
Just before we reached the TOC; we noticed that the FMS went black. RNAV data was still displayed on the MFD; but we had no control or input.  The CA stated we needed to pull out our high altitude charts and start planning for a VOR approach. We were currently direct CVE so he put in the frequency and switched to VOR mode. I tuned in and idented. I let ATC know at that point that we were negative RNAV and requested the RIICE SEVEN arrival as it was most identical to the DRLLR RNAV arrival. I plugged in and idented the crossing VOR radials to identify points on my side and the CA plugged in the route VOR frequencies and radials on his side. Each time we were transferred to another controller; each person was not aware we were unable RNAV so we had to explain...each time. Once we got transferred to Houston apch (124.35); we were given RV for 26L. After that; the flight and workload were conducted as normal and we arrived safely to our gate.There was definitely a workload overload associated with flying green needles; switching frequencies; identing frequencies; changing radials; descent planning; landing data; etc. All in all this occurrence ran very smoothly. The captain and I worked together; briefed and discussed what each of us was doing; continued CRM and communication and worked together as a team to manage the situation at hand safely. Due to not being exactly sure if we made our points within limits; we decided to fill an ASAP report to be on the safe side. We were never contacted or corrected by any controlling agency.This was an unpreventable event. It was definitely a learning event as this is the first time this has happed to me in the 121 environment. The only thing that caught me off guard was how fast we would pass our points and the workload management so next time; although briefed; I feel I could be more aware of that and try to plan ahead a little better with the radials; frequencies; radio calls; etc.
EMB-145 First Officer reported FMS failed on a leg to IAH; noting the increase in workload associated with that loss.