Sealevel synchronous serial products fall into three categories: ZiLOG Z16C32 based devices, ZiLOG Z85230 based devices and older ISA DMA channel cards.
The fastest family of Sealevel synchronous serial products is built around the ZiLOG Z16C32 IUSC which has an onboard DMA controller. All Sealevel Z16C32 based products have 256K of onboard RAM that is mapped to the PC’s internal memory. Using the SeaMAC V5 driver, the onboard DMA controller allows these products to achieve burst rates of 10 Mbps and sustained data rates of up to 6 Mbps.
The Sealevel synchronous serial products built around the ZiLOG Z85230 ESCC are supported by the SeaMAC V5 driver in interrupt mode. These products make use of the small onboard FIFO (8 byte receive, 4 byte transmit) in the ZiLOG Z85230 to achieve a maximum burst data rate of 128 Kbps with a sustained data rate of up to 56 Kbps.
The older ISA DMA channel synchronous serial cards are built around the ZiLOG Z85230 ESCC. Using the SeaMAC V5 driver, these cards operate in interrupt mode and are limited to a maximum burst data rate of 128 Kbps with a sustained data rate of up to 56 Kbps.