Tandom TM100 5¼-inch Floppy Disk Drive

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The Tandom TM100 series of 5¼-inch floppy drives were full height devices and were offered in several configurations. The drives were used in IBM 5150 and 5160 Personal Computers (with a custom 'IBM' bossed faceplate), and many other machines besides.

In common with most 5¼-inch drives, the drives had no outer casing as such, and so could easily be damaged when servicing.


Models

Model Type Tracks Tracks-per-inch (TPI) Formatted Capacity
TM100-1 Single sided 40 48TPI 180KB
TM100-2 Double sided 40 48TPI 360KB
TM100-3 Single sided 80 96TPI 360KB
TM100-3M Single sided 80 100TPI 360KB
TM100-4 Double sided 80 96TPI 720KB
TM100-4M Double sided 80 100TPI 720KB

The "M" suffix may have been used for the 100TPI varients as Micropolis had produced a 100TPI drive early on.

Jumpers

TM100 Logic Board
  • Programmable Shunt Socket (1E):
    • HS - unused; must be cut
    • DS0..DS3 - Drive select
    • MX - multiplex; used only in single-drive systems when drive logics should remain enabled at all times. Must be cut in a multi-drive system.
    • (Spare)
    • HM - unused; must be cut
  • R50/R51 - Selects power save mode via 0-ohm resistor:
    • R50 - 3.8W saving at idle, by removing 200mA current to stepper motor when drive is not selected
    • R51 - no power save mode
  • W1 - Side Select:
    • Open - single-sided (TM100-1)
    • Closed - double-sided (TM100-2)
  • W2/W3 - Write Flip-Flop Control:
    • W2 closed, W3 open - Disables set and preset lines on write flip-flop only during internal N Write
    • W2 open, W3 closed - Dsiables set and preset lines on the write flip-flop continuously
  • W4/W5 - Write Protect Control:
    • W4 closed, W5 open - Write Protect Control responds to a write-protected disk
    • W4 open, W5 closed - Write Protect Control is inhibited
  • W6/W7/W9 - LED Control:
    • W6 closed, W7/W9 open - LED controlled by Drive Select
    • W6 open, W7/W9 closed - LED controlled with N In Use (J1-4)
  • W8 - Drive Select 3 Enable (DS3 disabled if open)
  • W10 - Door Lock (lock is disabled if open)

The drives had a standard 14-pin DIP socket (RP1) for a terminator resistor network (for example a Beckman 899-3-R150).

Reliability

  • Soft Error Rate: One error per 109 bits read
  • Hard Error Rate: One error per 1012 bits read
  • Seek Error Rate: One error per 106 seeks
  • MTBF: 8000 Power-on-hours under typical usage (25% duty cycle)
  • Media Life: 3 x 106 Passes per track and 30,000 insertions
  • Head Life: 20,000 media-contact hours

Reference Materials

See Also

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