Gestetner A193 Service Manual page 798

D8905
The D8905 is an ASIC which contain the following functions.
• DRAM controller
• Video controller
• ROM and I/O interface
• Three I/O DMA channels
• Interrupt controller
• Rotator
• Bi-directional parallel interface
• Two UARTs
• Decoder
D9001MF
The D9001MF is an ASIC which has the following functions.
• Normal mode, to carry out edge smoothing on 600 dpi video data
• Adaptive mode, to convert 300 dpi data to 600 dpi and perform edge
smoothing
• Converts data for toner saving
RAM
Two Mbytes of DRAM are provided on the board. It consists of 4 pieces of 4
Mbit fast page mode DRAM (256k x 16 DRAM).
NV RAM
The board contains a 512-byte NV RAM. It is used for holding parameters
(such as the baud rate, the printer name, and the default mode setting), that
must be kept after the machine is switched off.
ROM
Two ROM chips (1M x 16) are used for storing the PCL code and font data,
test page data, and multi-language display message codes for the front panel
(4 megabytes). Page mode ROMs are used for optimum performance.
SIMM Slots
Two SIMM slots are provided for RAM expansion. 1, 2, 4, 8, or 16 MByte
standard SIMM modules can be installed. As a result, up to 32 Mbyte of RAM
are installable (16 Mbyte x 2).
NOTE: An identical SIMM must be installed in the second slot.
SM 1-9 (A643)