The Ace only has 1mb on the mobo. In the mobo tower side is the port for a 1mb expansion board. It's a weird looking thing that plugs in, hard to miss. Note the system must have 2mbs in the mobo before an i/o slot expansion board can be used. Meaning you must have the weird 1mb upgrade board inside on these. It uses the same upgrade as the Pro models, but they have a different bracket to lock it in place though.
Also be aware you can't just put ram inside. You will need a system disk and a keyboard (or mouse if you use the weirdo 1.0 sys disks) in order go above 1mb as well.