TMS279X Datasheet, PDF (1/40 Pages) Texas Instruments – FLOPPY DISK FORMATTERICONTROLLER FAMILY

PROGRAMMABLE
PRODUCTS
TMS279X
FLOPPY DISK FORMATTERICONTROLLER FAMILY
JUNE 1984
• On-Chip PILL Data Separator
• On-Chip Write Precompensation Logic
• Single + 5-V Supply
• Accommodates Single-and Double-Density Formats
- MM3740 (FM)
- IBM34 (MFM)
• Automatic Seek with Verify
• Multiple Sector Read/Write
• TTL Compatible
• Programmable Control
- Selectable Track-to-Track Access
- Head Load Timing
• Software Compatible with the FD179X Series
• Soft Sector Format Compatibility
description
The TMS279X family are N-channel silicon
gate MOS LSl devices which perform the
functions of a Floppy Disk Formatter/Controller
in a single chip implementation. The TMS279X,
which can be considered the end result of both
the Western Digital FD1771 and FD179X
designs, is IBM compatible in single-density
FEATURES
Single Density (FM)
Double Density (MFM)
True Data Bus
Inverted Data Bus
Side Select Out
Internal CLK Divide
2791
X
X
X
X
2793
X
X
X
X
2795
X
X
X
X
2797
X
X
X
X
mode (FM) and System 34 compatible in
double-density mode (MFM). The TMS279X
contains all the features of its predecessor the FD179X plus a high performance phase-lock-loop data
separator as well as write precompensation logic. In double-density mode, write precompensation is
automatically engaged to a value programmed via an external potentiometer. In order to maintain
compatibility, the FD1771, FD179X and TMS279X designs were made as close as possible with the
computer interface, instruction set, and I/O registers being identical. Also, head load control is identical. In
each case, the actual pin assignments vary by only a few pins from any one to another.
The processor interface consists of an 8-bit bi-directional bus for data, status, and control word transfers.
The TMS279X is set up to operate on a multiplexed bus with other bus-oriented devices.
The TMS279X is TTL compatible on all inputs and outputs. The outputs will drive one TTL load or three LS
loads. The 2793 is identical to the 2791 except the DAL lines are true for systems that utilize true data
busses.
The 2795/7 has a side-select output for controlling double-sided drives.
Scanned and Edited by Michael Holley - Aug 21, 2001 - [e-mail]
Texas Instruments was a second source for the WD279X and this data sheet is almost identical to the
Western Digital WD279X-02 Data Sheet and Application Note. (But has larger figures and is more readable.)
Active low signals use a trailing # instead of an overbar.