Keyboard Adapter; Direct Memory Access (Dma); Timer; Printer Data Link - IBM 6360 Product Support Manual

Main
Program
Main
Program
Figure 6-5. Interrupt Handling
There is also. a nen-maskable interrupt
(NMI) which is a hardware interrupt.
The NMI is an error reporting inter-
rupt which reperts errers in the sys-
tem memory, system time out, or occurs
when a dump switch eperation is initi-
ated.
Keyboard Adapter
This adapter is located on the system
~ard and is the interface between the
keyboard and the , , ' system electronics.
It provides a path for data input and
keyboard controls.
Direct Memory Access COMA)
Direct Memery Access (DMA) centrels
the addressing ef data to. and frem the
diskette adapter card and the memery
card during a read/write eperatien.
DMA is also. used during 3277 DE eper-
atiens.
Timer
The timer is a clecking device en the,
system card that records the number ef
50 millisecond intervals since the
last IPL. The timer pulses are also.
used by the system seftware fer diag-
nestic programs'and:custemer pregrams.
Printer Data 'Link
The last majer functien on the system
card is the printer data link, which
is the interface between the system
card and the printer. This interfac,e
prevides a path, fer data transfer
between the system electronics and the
printer.
MEMORY CARDS
The Displaywriter has five memory
types which are designated A to E. A
descriptien ef the types fellews:
• Type A. This memery cenfiguratien
always consists ef a 160A er a
192A bas e type memory card in rew
E ef the distribution beard.
•
•
Type B. This memory cenfiguratien
always censists of a 128K,192K,
224K,
or a 256K base memory card
in row
E
of the distribution
board.
Type C. This memory configuratien
always censists of a . 160A base
type memory card in row E ef the
distribution board plus an appro";'
priate type
B
memory extender card
in row F.
6-6 IBM Displaywriter Product Support Manual