Iv-3. Description Of Block Diagram; Cpu - Tandy 1400LT Service Manual

IV-3. Description of Block Diagram
The Block Diagram of the TANDY 1400LT on the previous page shows the basic function divisions. The following
are brief descriptions of the functions of each block.
CPU
CLOCK GENERATOR
DMA CONTROL
INTERRUPT CONTROLLER
BUS CONTROL
TIMER/COUNTER
KEYBOARD/SENSE/CONTROL PORT
INTERNAL KEYBOARD
KEYBOARD CPU
REAL TIME CLOCK
DISPLAY CONTROL
UART
FDC
VFO
3.5 INCH FDD UNIT
NEC V20
Custom IC for dual clock speed
82C37A-5 CMOS 4 Channel DMA controller (MAX DMA
transmit speed 5MHz)
7 1059C CMOS 8 channel interrupt controller.
7 1088C CMOS bus controller. Manages bus arbitration.
7 1054C CMOS 3 channel timer/counter
82C55 equivalent IC. Or use subset of 82C55.
76-Key full keyboard.
80C49 Microprocesser to scan keys and transmit codes to system.
R I C H 0 RP5C15
V6355
TC8570P RS-232C interface
pPD72065C CMOS type of 765 floppy disk controller.
SED9420CAC
3 . 5 inch double-sided,double-density front loading.
4-3