Microtan-R

This page contains the details of a project being undertaken by David Fry and me to build a modern version of the Microtan 65 system. Many of the items developed are available for purchase at the shop here. A suitable starter project is described here.

The PCBs are being developed using KiCad (kicad-pcb.org). The KiCad project files have been archived in the ZIP files in the relevant sections below and include the Gerber files for PCB production.

MT65-R CPU

This is a modern replacement for Tangerine's latest version CPU card. It is fully compatible with the original and has the following enhancements:

Bare MT65-R CPU v1.0b PCBs are available for sale in the Shop

Character Generation EPROM

Note: The FORTH programs require Rev2 code for its 'Words' to be displayed correctly. This is because the 6502 code stores Words with the 8th bit of the last character set to denote the end of the word.

TANBUG v2.3 EPROM

TANBUG v3.1 EPROM

TUGBUG v1.1 EPROM

Note: TUGBUG cannot be used with a MT65-R CPU board in Single Board configuration (ie with the 3 links closed and no TANEX). Explanation here

TANEX-PLUS

This is a modern replacement for Tangerine's Tanex card. It is fully compatible with the original and has the following specification:

Note: UART 6551 may be substituted with 65C51 in PCB versions 1.0b and above.

Bare Tanex-Plus v1.0b PCBs and programmed memory are available for sale in the Shop

X Bug EPROM

U13/U14 EPROM

U13 is a 27512 Eprom that holds the first 4 pages of memory that each map into the $C000-$EFFF area of the Microtan System memory.
Optionally, U14 is fitted to hold a futher 4 pages of memory.

The list of curent options for EPROMs U13 and U13 are here.

GAL Files

64K RAM

A modern 64K RAM board produced by Barry Graham and is based on the TUG 64K RAM board. Note: This board is for use with the original TANEX. It cannot be used alongside the TANEX-PLUS as both board address the same memory range.

Full details are available on Barry's web-page.

TANDOS-R

Modern replacement for the Tangerine TANDOS 65 board.

EPROM U17

EPROM U17 is a 2732 EPROM containing both the TANDOS and DBASIC images.

HRG-R

This is a modern replacement for the Tangerine High Resolution Graphics (HRG) board.

Provides 256x256 pixel high resolution graphics screen. When used with the HRG Toolkit can also provides a 51 character x 45 line high-resolution text screen. Modulated UHF and composite video outputs available.

Bare HRG v1.0b PCBs and programmed Toolkit EPROMs are available for sale in the Shop

James Price has been experimenting with the HRG board. He has generated a document that captures his work.
Adventures with the Microtan HRG-R.pdf
The associated software files are also available on my FTP server.

CVB-R

This is a modern replacement for the Mousepaket Colour Text and Graphics board.

Provides 64 (alphanumeric or graphic) Teletext character by 25 row display.
Software switch provided for switching video output between the CVB-R screen and the MT65 CPU screen. RGB/SCART and composite monochrome video outputs available.

Requirements

TANBUG v3B (note: this version has had the Hexpad routines removed to make space for the CVB code).
If video output from BASIC is required, a modified BASIC Eprom D3 is required.
TV/Monitor/Video converter with RGB/SCART input

80/82-R

A modern Video 80/82 board produced by Barry Graham and is based on the TUG board that was subsequently adopted by Tangerine.

Requirements

TUGBUG monitor.

Full details are available on Barry's web-page. The instructions for configuring the Microtan-R system to use the Video 80/82-R board are here

EPROMs

The main operating system firmware for the Video 80/82 Card is VBug. Two versions were produced, VBug 1 and VBug 6. These are described on the Firmware page.

The Video 80/82 card is supported by the Video 80/82 Card Toolkit which is located in the TANEX socket E2. Two versions were produced supporting VBug 1 and VBug 6. These are described on the Firmware page.
The toolkit is initialised by issuing the command POKE34,0:POKE35:232:P=USR(P) either after loading BASIC or by including this command as the first line of any program that requires the toolkit. Alternatively it can be initialised automatically when BASIC is loaded if BASIC Mod 4 is embodied. However, this does not work when loading the DOS version DBASIC, VBASIC should be used instead.

VBASIC

VBASIC is a DOS program which performs the following: Selects the appropriate TANEX-Plus ROM memory page that has BASIC and the Video 80/82 Toolkit (Option K), loads DBASIC and initialises the Toolkit. The instructions for installing VBASIC are here

Soundcard

This is modern replacement for the Bulldog Soundcard. It includes a battery backed Real Time Clock module. The PCB design, Manual and supporting software were developed by James Price. It has the following specification:

Supporting Software

Because of the size of the associated .wav files, they are held on my FTP server. If you wish to download any of these files, please send me an email (address is on the Home page) and I will provide access information. All .wav files have been saved at 'FAST' speed.

James has also been experimenting using the soundcard as a musical instrument. He has generated a document that captures the various steps he has taken.
SoundcardAdventures.pdf
The associated software files are also available on my FTP server.

MT-R EPROM Programmer

This EPROM Programmer is capable of reading and programming 2716 and 2732 EPROMS. It connects to TANEX parallel port sockets A,C and D and requires an external power supply to provide the Vpp programming voltage.

Keyboard

Replacement for Tangerine Keyboard (MT020)

The circuit is identical to MT020 Issue 3 except the mechanical Caps-Lock switch is replaced by a software toggle function.

Photo of Keyboard in its case.

Keypad

Replacement for Tangerine Keypad

System Rack

What started life as a bespoke 19 inch 4U system rack has been modified to accommodate the Microtan Circuit Boards and fit into my existing Vero 19 inch enclosure. This involved removing the end plates, cutting them down to size and re-drilling the holes for the screws that hold the 6 longitudinal rails in place.

Motherboard

The motherboard has been designed to accommodate CPU, TANEX and 5 expansion slots. The slots are 1 inch apart to allow for a wider PCB form factor and increased cooling. Tanbus expansion slot signal lines 19b and 20b have been earmarked for Video1 and Video2 signal. Each may be configured by on-board jumpers to link to Tanbus CPU slot signal lines 19a or 20a.

This motherboard has now been replaced with a prototype for the full-sized Backplane-R described below.

Full-size Backplane

The Backplane-R is a direct replacement for the Tangerine MT0010 Backplane. It accommodates CPU, TANEX and 9 expansion slots. Again the slots are 1 inch apart and expansion slot signal lines 19a and 20b earmarked for Video1 and Video2 signals as described above.

The onboard circuitry provides buffering for the O1, O2, CLK, SYNC signals from the CPU. Additionally Memory Page management for the memory range $2000-$BBFF is possible utilising the Block Enable signal. A full description is available here. However, this can only be used when an original TANEX is fitted. If a TANEX-PLUS is fitted with its $2000-$BBFF memory permanantly enabled, then this range cannot be overlaid by other boards.

Power Supply

Power is supplied to the motherboard by a 65W Meanwell 1496-RQ-65B Quad Output enclosed power supply providing dual 12 volt and 5 volt supplies.

Other Projects

Serial Keyboard Interface

Construction notes for creating a Serial Keyboard interface to the Microtan 65 supplied by Danny Page. This interface enables a PC-AT keyboard to used with the Microtan system.

TANBUS Extender

Plugs into any TANBUS slot on the motherboard. Microtan board under test plugged into the extended socket. Allows work to be undertaken on a Microtan board under test outside the system rack. Test points available for all TANBUS signal lines.

Other Data

Memory Map