Toshiba T4500 User Manual page 6

The T4500 and T4500C system board shown in Figure 1-4 is composed of the following major
components:
An i486SX-20 CPU
Super Integration (SI) T9901, which stores the following components:
Two Direct Memory Access Controllers (DMAC): 82C37
Two Programmable Interrupt Controllers (PIC): 82C59
One Programmable Interval Timer (PIT): 82C54
One Floppy Disk Controller (FDC): TC8565
One Serial Input/Output Controller (SIO): TC8570
One Variable Frequency Oscillator (VFO): TC8568
One I/O Controller
One Printer Port Controller
One Speaker Controller
A Real Time Clock (RTC)
One T9934 chip is used. The T9934 has 128 bytes of memory. Fourteen bytes of memory
are used for the calendar and clock. The remaining 114 bytes are used for the system
configuration data.
A Keyboard Controller (KBC)
One M37452M4 chip is used. This KBC includes the keyboard scan controller and key-
board interface controller. The KBC controls the internal keyboard, external keyboard port,
PS/2 mouse port, and ball point quick port.
Memory configurations
Standard RAM:
Cache memory:
BIOS ROM:
Video RAM:
Optional memory cards expand memory to a maximum of 20 MB.
VGA display controller: WD90C26A (144-pin) (3.3 volt operation)
This controller controls internal and external VGA compatible display. It can display the
internal and external display at the same time.
1-6
4 MB
8 KB (inside CPU)
128 KB (96 KB are used)
This Read Only Memory (ROM) contains Initial Reliability Test (IRT),
Basic Input/Output System (BIOS), and video BIOS.
512 KB