Tandon TM848E

Make: Tandon

Model: TM848 E (TM848-2E)

serial no: 84001741

media: 8 inch (203.20 mm) IBM industry standard diskette

density: 48 tpi (tracks per inch)

tracks: 77 tracks per side

rotation speed: 360 rpm

data transfer rate: 500k bits per second

unformatted capacity: 1.6 megabytes per disk

power: 24 V DC @ 700 mA (max is 2.25 A), 5 V DC @ 450 mA

typical current requirements for 24 V DC: spindle motor 170 mA, stepper motor 400 mA, electronics 130 mA

power dissipation: 20W

connector: 50 pin flat ribbon connector 3M schotchflex (partno 3415), connects to circuit board

interface signals: TTL compatible, logic true (low) is +0.4 V maximum, logic false (high) is +2.4 V minimum.


Links: FDADAP adapter, FDDC converter, Dave Dunfield: connecting drives to PC, IMD etc, Keir's Disk-Utilities, disk-imaging-vcfe-2014 (PDF), SURE Electronics, Herb Johnson: Tech information on floppy disks drives and media,

local links



2020-02-28: tested the floppy drive with a few boxes of 8 inch floppies and a FluxEngine updated to the latest firmware and software. Sometimes, the floppy drive doesn't react at all - opening the lever on the floppy drive (the one that lowers the head) helps sometimes, sometimes I need to unplug the FluxEngine and plug it back in. Managed to read three boxes of floppies, all read ok, and only a couple of CP/M floppies had read errors.

2020-02-28: psu - at Bitraf this evening, I soldered wires to a mh-mini-360 buck converter (like this one), connected its input to 24V output from the external psu, adjusted output to 5V and connected it to the "5V end" of the wiring. No I can used my TM838-2E with just the psu, FDADAP and a FluxEngine. Nice!

2020-02-28: the external PSU is a Mean Well NES-100-24; output 24V 4.5A.

2018-07-02: finished the cables, and connected the drive to htpc, a Pentium 4 machine.

2018-06-30: (at Bitraf) I soldered up power cables. With both +24 V and +5 V the floppy drive acts ok, if I insert a floppy and close the lever, the floppy spins for a few seconds, like it is supposed to. No lights in the display on the FDADAP, but I'm not sure if it is supposed to light up at all without a floppy controller (read PC) connected.

2018-06-30:TM848 power connector (P2) - with the drive the correct way up (lever on top, above floppy), looking from the back of the drive the pins are numbered (from left to right)

top row 6, 4, 2

bottom row 3, 5, 1

pin assignments are * 1 + 24 VDC * 2 24 VDC GND (return) * 3 5 VDC GND (return) * 4 (no connection * 5 + 5 VDC * 6 5 VDC GND (return)

2018-06-30: psu 24V - I have a Mean Well NES-100-24 (input 200 - 240 VAC 1.5A, output 24 VDC 4.5A) psu, that should work nicely.

2018-06-28: power connector - I tested with a modified four-pin Molex (standard PC connector) with the fourth pin cut off - it fits physically into the power connector on the TM848E. If it gives a good electrical connection too, I have a (temporary) solution.

2018-06-27: cable - I made a short 50 pin cable. If it works, all I need is a connector for the power cable on the drive. 2018-06-27: today, on my way to the office, I picked up the package at a PostNord pick-up point (Coop Prix Hasumannsgate). Sure, this was my lost package from Amazon. After all the trouble asking about it, and getting a refund and everything. Well, I finally got my connectors.

2018-06-26: this afternoon, I found a (physical) pick-up notice from PostNord in my mailbox. A different sender, different tracking id. Could this be my lost package from Amazon?

2018-06-21: IDC connector - today Amazon says "Your package may be lost. Packages are rarely this late and we're sorry yours still hasn't arrived. You can wait another couple days or check out these options.". Not impressed.

2018-06-20: IDC connector - It is getting evening here, and Amazon still says "Now expected today" about my package.

2018-06-13: IDC connector - the packaged with 50-pin IDC connectors was supposed to be delivered yesterday. Now Amazon says "Now expected June 13 - June 20. We're sorry your package is late - We're working with the carrier to get your package back on track, and we'll let you know when your package is out for delivery. Please come back June 21 if you still don't have it and we'll help you out. Was expected Tuesday, June 12".

2018-06-01: cable - the card edge connectors and the flat ribbon cable arrived.

2018-05-26: cable - I ordered necessary connectors and flat ribbon cable to build a 50-pin cable for the floppy drive <--> FDADAP part.

2018-05-24: strapping - factory - two-sided diskette installed 2S installed, spindle motor control M1, M3 installed, Power save PS installed, head select S2 installed, Motor control signal low true MOL installed, in use not latched NL installed, inhibit write when write protected WP installed, external write current switch XC installed,

2014-12-03: I picked up the package with the NES-100-24 PSU on my local PIB (Rimi Trondheimsveien) this afternoon.

2014-12-02: today I got a pick up notice about the NES-100-24 PSU in my (physical) mailbox. Wow - 42 days from shipped...

2014-10-30: I got a PSU at Bitraf. Model: S-400-24. Input 220 V AC, output 24 V DC 16.5 A which can be used. Now I just need cables.

2014-10-27: the package from D Bit arrived, straight into my mailbox.

2014-10-21: Ordered a FDADAP from D Bit at USD 40.- paid via PayPal. Also got a shipping notice for the NES-100-24 PSU.

2014-10-20: PSU - ordered a MW 24 V 4.45A PSU (model: NES-100-24) from eBay, at USD 27.- including shipping. Seller is SURE Electronics.

2014-10-20: sent a mail to D Bit, asking about FDADAP availability, and how to pay.

2014-08-31: strapping: strap block closest to card edge connector: DS1 is strapped (selects drive 0 via J1-26), R (Ready via J1-22) is strapped, DC (Disk Change via J1-12) is strapped, XC (external write current switch) is strapped, 2S (two-sided diskette signal via J1-10) is not strapped, strap block close to ROM: M1 (5 second motor off delay enabled) is strapped, M3 (motor control using drive select) is strapped, it looks like PS is active trough pcb traces (no jumper block installed),

2014-08-31: this evening I unpacked the drive (inside the bubble wrap it was packed in plastic ziplock bag, there was also a round of bubble wrap around the drive itself). It is a TM848 E. It has a folded paper taped on one side, the readable lines are

"MFX-500 version 1.07"
"STATION 0000"

how do I tell if this is a one-side (TM848-1E) or two-side (TM848-2E) drive? Looking at the head assembly, there are two black cables, one going to each side, so maybe it is a two sided drive? Update: according to a discussion on the VCForum, yes two black cables = two-sided drive.

2014-08-27: First I got a pickup notice (both on email and as a sms on my phone), then I picked up the package, it was sent locally with PostNord and delivered to a grocery store nearby (Rimi, Hausmannsgate 19). The package was a medium flat rate box, and inside the drive was securely packed in bubble wrap plastic. The inside of the package also had a packing slip.

2014-08-18: I got a shipped notification from eBay, with estimated delivery between Tue. Aug. 26 and Wed. Sep. 3.

2014-08-17: Somewhere on the vintage computer forum, it was mentioned that the Tandon TM848E 8 inch drives were available for reasonable money. So I found one on eBay (from seller malloryglobal) located in the USA, for USD 95.- and shipping USD 43.01. The only think I was sceptical about was that the seller used eBay's GSP (Global Shipping Program), because I had heard horror stories about it taking forever to ship stuff and so on (on the plus side, GSP included import charges, USD 35.93). But I decided to take a risk, and bought this. Total price was USD 173.94, which is NOK 1114.37.