Specifications

Computer Architecture and Maintenance (G-Scheme-2014)
Table . Differences Between PC/XT and AT Systems
System Attributes
PC/XT Type 8-Bit 16-, 32-, 64-Bit AT Type
DMA channels 4 (3 usable) 8 (7 usable)
Maximum RAM 1MB 16MB/4GB[1] or more
Floppy controller speed 250Kbps 250, 300, 500, and 1000Kbps
Standard boot drive 360KB or
720KB
1.2M, 1.44MB, and 2.88MB
Keyboard interface Unidirectional Bidirectional
CMOS memory/clock None
standard
MC146818-compatible
Serial-port UART 8250B 16450/16550A or better
Prepared By – Prof. Manoj.kavedia (9860174297 – 9324258878 ) (www.kavediasir.yolasite.com)
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