Hardware Description; Controller Module; Controller Board - NCR Decision Mate V Hardware System Technical Manual

SYSTEM TECHNICAL MANUAL

HARDWARE DESCRIPTION

The controller module consists of two printed circuit boards, the
controller board and the graphics controller board. Two types of
graphic controller boards are used: one, with 32Kbytes of RAM
for systems with a monochrome CRT, the other, with 96 Kbytes
of RAM for systems with color CRT.
CO NTROLLER BOARD
The controller is a 300mm x 290mm printed circuit board and
utilizes a Z80A microprocessor and auxiliary logic to drive and
control a family of 8-bit common memory and peripheral modules.
Figure 2.1 shows a block diagram of the controller board.
• Z80A microprocessor is operated with a 4 MHz clock.
• The LSI flexible disk controller contains the circuitry and con­
trol functions for interfacing one or two flexible disk drives. It
is capable of supporting double density format including
double sided recording. Hand shaking signals are provided
which make DMA operation easy to incorporate with the aid
of the DMA controller integrated circuit.
• The RAM controller provides mulitplexed addresses and ad­
dress strobes, as well as refresh access arbitration for the
64 Kbytes dynamic RAM contained on the controller board,
and also for the memory expansion modules. (Up to a maxi­
mum of 256Kbytes, or 512Kbytes with the multi-layer con­
troller board).
• The loudspeaker is designed to produce tones for keyboard
acceptance click, bell, and music demonstration. A separate
circuit provides the frequencies from 110Hz to 1174.7Hz. The
small audio speaker is housed on the controller board. The
loudness is adjusted by a user-accessible potentiometer.
• The keyboard interface connects the ASCII encoded keyboard
to the controller board by a four-wire cable carrying logic
ground, frame ground, +5V, and data signal. The keyboard is
polled by the controller. When a key is pressed, the serial
data is returned on the same line. For a detailed description
see the keyboard description.

CONTROLLER MODULE

HARDWARE DESCRIPTION
2-1