> On Oct 19, 2018, at 1:14 PM, Al Kossow via cctalk <cctalk@classiccmp.org>
> wrote:
>
>
>
>
>>> IBM developed a Token Ring card for the PC in time for its launch
>
> IBM's initial networking for the PC (The PC Network) was broadband, based
> on technology from Sytek. 4Mb token ring was released later. Exact dates
> are in the manuals on bitsavers.
>
> http://bitsavers.org/pdf/ibm/pc/pc_network/6322916_PC_Network_Technical_Reference_Sep84.pdf
That's basically Ethernet except very slow (2 Mb/s, even slower than
"Experimental Ethernet"). But it's described as CSMA/CD, and it uses the
much-cursed Intel 82586 Ethernet chip.
Token ring ended up a failure because it was slow and completely incompatible
with other 802 networks, from the backward addresses to the bizarre
pseudo-multicast scheme to the source routing bridges. In spite of IBM
marketing claims, 802.5 data link layer is not a well behaved design. Later
token rings, like FDDI, used the 802.4 token passing algorithm ("Timed token"),
avoiding the 802.5 algorithms completely.
paul
