The module next to the coil - I believe that is not standard equipment. The slot-head screws don't look original, and neither do the wires and terminals. Does the car have a points distributor or the electronic type? That module could be a replacement for the finned module mounted on the distributor (which often fails). It has a fairly simple purpose - switch the coil on and off in response to the magnetic (reluctor) pickup. If it's working, best left alone
The other module, by the strut tower - Chas is right, it's the control module for the fuel cutoff on the overrun. To sense the engine RPM, it has a connection to the ignition coil, which can confuse you into thinking it's an ignition device, but it's not. It works by measuring the rate-of-change of the engine RPM, and also takes a signal from the black wire attached to the throttle plate stop screw/spring. When the throttle is closed, and the engine RPM is declining only slightly, the control module cuts off the fuel. When the engine RPM reaches some low point (under 2000RPM, possibly lower if the rate-of-change is slow), the control module reinstates the fuel. The fuel control is by the large solenoid (red wire) on the carburettor that Chas so nicely illustrated.
If a replacement carburettor has no throttle contact switch and no cutoff solenoid, then you're out of luck - the control module becomes a chocolate teapot, albeit in square black-box form.
Fuel cutoff on the overrun makes only a modest difference to fuel economy, probably more in rolling country hills, and less useful in towns on the flat like Hamilton
By the way, the idle speed control that Chas mentioned (on later Uno 70 models) is accomplished not by electronics but by one or three thermo-devices. The 1987 models have a small bar attached to the inlet manifold coolant supply, with two valves and an electrical switch - the switch cuts off the accelerator pump, which has a solenoid, to avoid the possibility of flooding the engine and also to reduce emissions during warm-up.
The other two valves are plumbed to a fast-idle capsule added on the carburettor (has the brass adjusting screw on the right-hand side of the photo from Chas that shows the carburettor fitted to the engine). The valves cut out at different temperatures (the blue-plastic valve at a lower temperature than the white-plastic valve), to give two-stage control. The year after that (1988), someone realised how complex this was, and simplified the system to one white thermovalve screwed into the inlet manifold, which controls just the fast-idle capsule. And the year after THAT, someone decided to fit fuel injection...
-Alex
