The only significant differences, aside from the logo, were a somewhat beefier power supply in the 8800a and a standard 18 slot motherboard. The 8800 had 4 slot motherboards that were chained together. The 8800a had the 18 slot board with options for how many connectors and card guides you could buy. Earlier 8800a models had the short round switches shared with the 8800, later versions seem to have had the flat 8800b switches. Typically the 8800a had later rev boards, but some 8800s did too. Erik www.vintage-computer.com them. --