"Real" speed of AT bus (MB/sec)?

Cliff C Heyer cliffhanger at cup.portal.com
Tue Sep 12 12:41:21 AEST 1989

I'm having difficulty getting
the specifications of the AT bus

What is the speed of the AT bus
in MBytes/sec? (Thats 
millions of 8-bit bytes per second).

I know it's rated at 8MHz, but does
that mean 8 bits are transferred in
parallel with each cycle, or 16 bits
with each cycle, or is the transfer
serial at 8 Mbits/sec?

Is I/O done in blocks so that, for 
example, 512 bytes can be transferred
via one I/O instruction, and the CPU
can go on to do other work while the
transfer takes place? (DMA) Or does
the CPU have to issue a memory write
instruction for each byte?

Please POST your answers.

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