TallyGenicom 6600 Series, Maintenance Manual, Page: 295 / 474

Data Controller
295
V8 ASIC
The V8 is a multi-function custom gate array ASIC containing all the logic for
the DC that is not contained in the MPC8245 processor. The V8 provides the
following services:
•
Memory Access Controller
•
SDRAM Controller
•
Flash Controller
•
Two DMA Channels
•
Operator Panel Interface
•
“Dot Plucking” and Adjacent Dot Checking
•
Interface to the “Cajun” Bus
•
Host I/O and Diagnostic Port
Memory Access Controller
All MPC8245 addresses go through the V8 ASIC. The V8 handles all address
decoding, chip selects, DTACKs, and so on.
SDRAM Controller
The V8 supports up to four banks of page mode SDRAM.
Flash Controller
The V8 supports up to four banks of flash memory.
DMA Channels
The V8 provides two channels for direct memory access. These channels
move data from the host interface or expansion bus to the SDRAM and vice
versa. One address is an I/O address, the other is a memory address with
auto-increment.
Control Panel Interface
The V8 control panel interface consists of five lines: serial clock, serial data,
and three select lines. It is the V8 that handles all parallel-to-serial conversion
(and vice versa) to and from the panel, as well as any special timing needed
when toggling select lines, etc.
“Dot Plucking” and Adjacent Dot Checking
“Dot Plucking” is a specialized DMA function that removes dot data from a dot
image buffer in SDRAM in a programmable manner, serializes it, and sends it
to the hammer bank. This function is actually controlled by the EC (see page
296), which has access to the V8 through the “Cajun” Bus Interface.