Original PC Hardware Reference
Original PC Hardware Reference
Original PC Hardware Reference
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CD: 30 <strong>Original</strong> <strong>PC</strong> <strong>Hardware</strong> <strong>Reference</strong><br />
Figure 6 shows the XT motherboard, which is also used in the Portable <strong>PC</strong>. The following is the<br />
technical data for the Portable <strong>PC</strong> system:<br />
System Architecture<br />
Microprocessor 8088<br />
Clock speed 4.77MHz<br />
Bus type ISA (Industry Standard Architecture)<br />
Bus width 8-bit<br />
Interrupt levels 8 (6 usable)<br />
Type Edge-triggered<br />
Shareable No<br />
DMA channels 4 (3 usable)<br />
Bus masters supported No<br />
Upgradable processor complex No<br />
Memory<br />
Standard on system board 256KB<br />
Maximum on system board 256KB<br />
Maximum total memory 640KB<br />
Memory speed (ns) and type 200ns Dynamic RAM chips<br />
System board memory-socket type 16-pin DIP<br />
Number of memory-module sockets 36 (4 banks of 9)<br />
Memory used on system board 36 64KB ×1-bit DRAM chips in 4 banks of 9 chips<br />
Memory cache controller<br />
Wait states:<br />
No<br />
System board 1<br />
Adapter 1<br />
Standard Features<br />
ROM size 40KB<br />
ROM shadowing No<br />
Optional math coprocessor 8087<br />
Coprocessor speed 4.77MHz<br />
Standard graphics CGA adapter with built-in 9-inch amber CRT<br />
RS232C serial ports None standard<br />
UART chip used NS8250B<br />
Maximum speed (bits per second) 9,600bps<br />
Maximum number of ports supported 2<br />
Pointing device (mouse) ports None standard<br />
Parallel printer ports None standard<br />
Bidirectional No<br />
Maximum number of ports supported 3<br />
CMOS real-time clock (RTC) No<br />
CMOS RAM None
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