TI-of-TTL replaces
Timex Interface M-397

TI-of-TTL has the functionality of the Timex Interface M-397, used to connect ZX Spectrum with the Timex FDD file server and is part of Timex Disk System. TI-of-TTL is made without GAL and custom chips (EFGJ161). By the way the memory is expanded 8 times to 32kB ROM (EPROM) and 8kB RAM (SRAM). With extra upgrades 128kB PEROM can be used.

TI-of-TTL was designed in 1997 to make the Timex Disk System hardware alive (people in Poland had have a lot of damaged interfaces with no chances to repair) and to upgrade it with ZXVGS.

One year later a cable TIC was developed to connect Amiga (via Parallel port) and PC (via LPT slot) in place of Timex FDD.

Caution! Due to still unknown reasons, TI-of-TTL doesn't work correctly with the NEC D780C-2 processors (Z80 clone).

Upgrade 2004

The 32kB EPROM can be changed to 64kB EPROM that contains also ZXROM (ROM contents used in ZX Spectrum). TI-of-TTL, like the original Timex Interface M-397, used the internal ZXROM and trapped it at some addresses (in at #0000 and #0008, out at #0604). The internal ZXROM had to have the tape patches and TR-DOS traps to use full ZXVGS possibilities. With the 64kB EPROM TI-of-TTL provides own ZXROM with these patches and traps, so no changes inside a computer are needed. (Also the ZX Spectrum emulator cartrige is no more required for Timex Computer 2068.)

It is not very diffilcult to install the modification. A multiplexer like 74LS157 or 74LS153 (also SMD) must be mounted at bottom board plus some track cuts and extra wires on both boards. Caution! After modification all through interfaces with own memory (e.g. Masterface) will not work anymore. Don't make the modifiaction if upgrading the internal ROM isn't a big problem for you.

The multiplexer switches between O5, O7 from latch (see schematics below)and A13, /M1 from edge slot to be provided as A13 and A14 of EPROM. /ROMCS pin at edge slot must be cuted and connected permanently to +5V. The ZXDIS signal from top board must be connected as A15 of EPROM and the multiplexer selection line. To the selection input of 74LS139, wheere A13 goes, must be connected AND gate, which inputs are A13 and ZXDIS signal. The AND gate can be build from 1kohm resistor inserted in A13 line and PNP transistor controlled by ZXDIS line (collector to ground, emitter to 74LS139 input).

For EPROM contents please see the ZXVGS TMX below. The 64kB EPROM should be filled as in the table.

Upgrade: Zebra TOS

Allows to run Zebra TOS (dedicated for 2068 ROM - the 24kB one installed in Timex 2068) when ZXROM is not found. A small SMD 74LS74 must be mounted on top board to make the RET at #0604 to be taken from interface ROM, not from computer ROM. (Because the 2068 ROM doesn't have RET opcode at #0604, unlike the ZXROM.) This upgrade cannot be joined with the above (Upgrade 2004), because when ZXROM is mounted inside, the 2068 ROM is locked permanently.

Upgrade 2005

The design in version v009 allowed to use 128kB ROM, however only 32kB were available (or 64kB with Upgrade 2004).

Extra 32kB (or 48kB when Upgrade 2004 installed) can be used for some purposes. This memory is seen only at power on, then is no more available. But this is enough to place there a test software, PREROM reprogramming software or even a favorite game or demo.

Upgrade 2005 includes also a possibility to enable and disable the ZXROM added by Upgrade 2004 with 2 jumpers. Only one jumper should be shorted - on bottom board when ZXROM of computer is used or on top board for ZXROM of TI-of-TTL.

In order to install jumpers - on top board a 1kom resistor must be inserted into /ZXDIS line just before 74LS139 input to make this input shortable to ground by the jumper. The transistor or diode must be removed from top board and ZXDIS signal connected directly to vertical slot. On bottom board a NPN transistor must be installed to close the /ROMCS line of edge slot (with emitter, collector to +5V). The base of transistor is connected via 10kohm resistor to +5V and through a jumper to ZXDIS in vertical slot (or one output of the 74LS157 can be used).

Files for download

stanowisko_zx.jpg 121.1kB (2007-03-21 22:25), uploaded by ArturGrutz

zestaw zx+128k (przeróbka) z TI-of-TTL + TIC + PC386 jako stacja FDD i HDD z działającym ZXVGS

ti2005.jpg 43.4kB (2005-08-07 00:51)

New case for TI-of-TTL, adapted in 2005.

zepsute.jpg 79.3kB (2005-08-07 00:35)

Set of 16 boards of Timex Interface M-397.

ti-of-ttl.html 7.5kB (2005-07-10 15:39)

[pl] Short description for user.

timex1999.jpg 63.4kB (2004-10-15 17:27)

Timex 2048 (opened) with memory upgrade prototype, TI-of-TTL and prototype TIC.

u2004tt.jpg 59.2kB (2004-07-12 13:33)

Upgrade 2004 top board top view.

u2004tb.jpg 89.1kB (2004-07-12 13:49)

Upgrade 2004 top board bottom view.

u2004bb.jpg 80.2kB (2004-07-12 13:25)

Upgrade 2004 bottom board bottom view.

tittlview1.jpg 66.8kB (2004-07-12 13:36)

Colour view to inside boards v005.

u2004bt.jpg 64.2kB (2004-07-12 13:31)

Upgrade 2004 bottom board top view.

tittlschem.gif 10.0kB (2002-02-26 19:38)

Schematics v008 by Jarek Adamski.

Links to other pages

See also

TIC - Timex Interface Cable

Cable used to connect Timex Interface M-397 (or TI-of-TTL) with LPT of PC or Parallel of Amiga.

TOS A.2

Timex Operating System A.2 for Timex FDD 3/3000.

ZXVGS TMX

ZXVGS for Timex FDD 3000 and Timex Interface M-397 (TI-of-TTL). Can use also PC as cable server.

Timex FDD 3

Timex FDD 3. The computer with floppy disk drives in Timex Disk System set.

Timex FDD 3000

Timex FDD 3000. The computer with floppy disk drives in Timex Disk System set.

Timex FDD emulation - YTF

Timex FDD emulation based on Warajevo 2.51, includes YABUS.TF upgrade and IDE interfaces. Requires PC @ 100MHz.

Timex Interface M-397

Part of Timex Disk System. Runs TOS A.2, CP/M 2.2, CPM22QED and ZXVGS operating systems.