E1330B: What is the difference between Model E1330B and Model E1458A?

Model E1330B has four 8-bit ports. The Model E1458A has twelve 8-bit ports.

Model E1458A has the ability to read the actual bit status while it is outputting on a port; for example, SOUR:DIG:DATAn:BYTE:BITm:MON?

The handshaking lines and modes are the same.