Isa/Vl-Bus Backboard; Isa Bus; Vl-Bus - NEC POWERMATE 4100M Service Manual

1-14 Technical Information
Mode
(Hex) Colors
2
7C 256
2,3
7E 256
1
8x8 charactor size
2
8x16 charactor size
3
Interlaced

ISA/VL-Bus Backboard

The ISA/VL-Bus backboard provides four ISA expansion slots and one Video Electronics
Standards Association (VESA) Local Bus (VL-Bus) slots. The backboard is plugged into
two bus connectors on the system board.

ISA Bus

The system board uses the ISA bus for transferring data between the processor and I/O pe-
ripherals and expansion boards. The ISA bus supports 8- and 16-bit data transfers and typi-
cally operates at 8.33 MHz. A connector is provided on the system board for attaching the
ISA/VL-Bus backboard.

VL-Bus

The VL-Bus provides an interface between the system's local bus and a VL-Bus option
board (graphics adapters, disk controllers, network cards, and so on). The VL-Bus uses a
standard 32-bit VESA connector and conforms with the VESA 1.1 local bus specification,
providing a set of standards that ensure compatible VL-Bus option boards. The boards op-
erate at the system clock speed (33 MHz) with 0 wait states. The VL-Bus slot can support
bus masters simultaneously.
Option boards on the VL-Bus can send and receive data much faster on the local bus than
on the ISA bus. The VL-Bus runs at the system's clock speed (33 MHz) instead of the stan-
dard ISA bus speed (8 MHz). Also, the Local Bus provides a wider bus width (32 bits) than
the standard ISA bus width (16 bits).
The VL-Bus slot is used in conjunction with an ISA bus slot. This feature allows a VL-Bus
option board full access to the ISA bus. For example, the VL-Bus option board may utilize
the parallel port via the ISA bus, or use the ISA bus REFRESH signal. Use of the ISA bus
is optional, as the VL-Bus has all signals needed to fully support a VL-Bus option board.
Table Section 1-6 Graphic Modes
Column
/Rows Buffer
100 x 37 A0000
128 x 48 A0000
Video
Clock
Resolution (MHz)
800 x 600 72.0
1024 x 768 80.0
Horiz Vert
Sync Sync
(kHz) (Hz)
56.6 70
48.1 87