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Murray Macabe
A comprehensive Technical Information Document
Author: Murray Macabe
Date: 1990
Issue G/Aug. l990 
The OPD computer was manufactured by ICL who badge engineered it as the MERLIN 
TONTO for BT and as the COMPUTERPHONE for Telcom. Australia (APT). The 3 models 
were released in late 1984/early 1985. A version for North America was produced 
in small quantity. The computer resulted from collaborative development by ICL, 
Sinclair and BT, with PSION providing the XCHANGE programs. The hardware 
skeleton is based on the Sinclair QL. This includes the 68008 CPU, the two main 
QL ULAs (Uncommitted Logic Arrays), the method of dynamic RAM (DRAM) and screen 
management, the real time clock and the microdrives. 
1.1 CPU 
The main processor is a Motorola 68008P8, 8X16 bit device with a 7.S Mhz clock 
and a 1 Mbyte memory address capability. A second processsor, an 8051 in the 
modem, controls the keyboard and the communications functions 
The memory map is shown in Fig.1. The main components of the map are:- 
1.2.1 RAM 
128k DFRAM (2 banks of 64K K 8 bit, using 4164-15 ICs) 
2K Battery backed CMOS RAM. (The PERMANENT STORE: a TC5516AP-2 IC). 
32k of RAM is allocated to the screen. This, plus standard demands, leaves 
approximately 75k of work space [ 150 blocks of 512 bytes ]. 
128K is reserved for expansion RAM. (To allow a total of 256k of DRAM). 
128k of Operating System (0S) (4 off 32K x 8 bit ROMs) (16K of Speech 
synthesiser ROM is controlled directly by the speech synthesizer IC and is 
outwith the 68008's memory map). 
64K is reserved for expansion of the Operating System. 
160k of ROM (144K XCHANGE + 14k Operating System, five 32K x 8 bit ROMs). 
64k maximum in ROM capsules in a 2-slot ROMPACK. 
128K maximum in ROM capsules in a 4-slot ROMPACK. 
The ROMPACK detail above refers to the OPD as released in 1984, the following 
changes subsequently occurred: 
i). In 1985 ICL introduced the 4-slot ROMPACK. Space for the 2, additional, 
'slots' was obtained by squeezing XCHANGE into 2 ROMs. Version 2.5 of XCHANGE 
plus the ICL firmware in the ROMPACK (CALCULATOR etc.) was containd in a 128k x 
8 bit PROM (i.e. a 1 megabyte PROM) and a 32k x 8 bit PROM (27256 equivalent). 
These devices were the XFAA01 (ICL/PSION - 1M) and XBAJ02 (PSION 256K). 
ii). ICL then developed their 128K memory expansion unit (MEU). This had XCHANGE 
2.5 in the two PROMs (as above) and a further 8k x 8 bit EPROM (27C64) 
containing the test/initialisation routines for the new memory and firmware for 
the MEU'S slow RS232 port. 
iii). PCML produced their smaller, neater 128k memory expansion, TELESTORE in a 
ROMPACK case. This had the test and patch code for the expanded memory, XCHANGE 
2.5 and the ICL firmware (CALCULATOR etc.) contained in two PROMs. These were 
the XFAA01 PROM and a 27C512 EPROM. 
The capsule addresses of the 2-slot ROMPACK are different from those of the 
4-slot at ROMPACK 192K is reserved for the 6 capsule addresses of the 2 ROMPACK 
types. As a results there is potential to operate the OPD with 6 capsules. PCML 
exploit this in the latest version of their TELESTORE which accommodates 6 
Six capsules, if some are multi-program canbe too much for the standard OS to 
accommodate. Appendix 1 shows how to alter the OS to accept a greater number of 
ROM programs if the INTERFILE ROMCAP is available. 
There is no 'spare' space in the OPD memory map. Space not listed was 'reserved' 
by ICL for I/O (Input/Output) and possible future applications. There are, 
however, 3 'reserved' 32k slots, that may be available if the address de-coding 
of ULA3 is improved and other changes made. 
The OPD DRAM REFRESH method is the same as the QL's i.e. there is no separate 
REFRESH circuitry. REFRESH is achieved by accessing the DRAM routinely to 
generate the VDU screen and for other regular, repetitive proceedures. This 
results in delays and a loss of potential memory speed. The OPD has advantage 
over the QL because much of the OPD memory is allocated to ROM which is not 
subject to the same delays as DRAM. 
1.3 MODEM 
The modem is a plug-in, BT approved (and designed), dual line, 
auto-dial/auto-answer unit based on the ADM7910 IC. The following facilities are 
1200 bps half duplex, (Bell 202, CCITT V23 mode 2) 
600 bps half duplex, (CCITT V23 mode 1) 
75/1200 bps full duplex, (Viewdata) 
300 bps full duplex, (Bell 103, CCITT V21) 
Different modems are available for different operating locations e.g. USA and 
Australia. Australian modems have distinctive 4 pin line plugs with the APT 
logo. Pulse or DTFM (tone) dialling can be selected by DIL switches in the 
modem. The keyboard is inoperable if the modem is absent. Transmission format is 
configurable from internal firmware e.g. parity, stop bits, data bits and start 
There is 1 (or 2 depending on the model) ceramic 'sounders' in the modem. The 
Ring Equivalent Number (FREN) of the OPD (modem plus telephone) is 1 per line. 
The maximum line loading, allowed by BT, to ensure reliable ringing, is REN 4 
e.g. 4 OPDs or 1 OPD plus 3 normal phones of REN 1 etc. 
A computer access directory with 'search-and-browse', short code dialling and a 
profile store is provided in similar format to the telephone directory (1.4 
1.4 TELEPHONE The telephone handset is a standard BT 'Sceptre' type. There is an 
8 ohm 250mW moving coil loudspeaker in the control unit but no in-built 
microphone. Facilities include 'hands-free' call initiation, loudspeaker call 
monitoring, auto-dial from memory or manual dial from the keyboard and store 
plus re-call/re-dial of the last 6 numbers used. The directory is capable of 
holding 500+ entries but at this level there is little memory left for other 
functions. The telephone directory has 'browse-and-search' facilities plus short 
code dialling A single screen priority directory can be displayed by the LIST 
key and there is a facility to record the cost of calls. 
The basic telephone functions for manual dialling are battery backed, allowing 
one line to make and receive voice calls if mains power is lost. 
This consists of a Texas TMP5220C IC with a vocabulary in a separate, custom ROM 
of 152 words, plus letters and numbers. Facilities include limited text-to-voice 
conversion from keyboard entry and playback-to-test. Up to 16 messages can be 
pre-assembled and 2 used, automatically, by time-of-day selection, for 
auto-answer of incoming voice calls. Incoming voice messages cannot be recorded 
There are 2 microdrives each of 100K nominal capacity (95K minimum). They are 
not identical to the QL drives in mechanical construction, or operational 
protocol, but the blank microdrive cartridges can be used on either machine. An 
adjustable 'end-of-life' warning is provided for tape data quality/total number 
of seconds used. 
[ The OPD micro drives have greater data packing density than the QL but more 
space between data blocks resulting in comparable overall capacity. Certain 
metal components are replaced with plastic and the amount of lubrication on the 
tape has been changed ] 
The clock is the same as the QL except that the start date is l/l/1970 while the 
QL start date is l/l/1961. The clock output is displayed in the Notice Board at 
the bottom of the screen. 
1.8 VDU (Monitor) 
The OPD control unit is designed to be permanently powered and to blank the VDU 
screen if the keyboard is not used for 10 minutes. Operating any key recovers 
the display. 
The ON/OFF switch removes full voltage from the monitor, but maintains a reduced 
supply to prewarm the tube heater for fast start-up This switch does not affect 
supplies to the control unit The intent was that the monitor should be switched 
OFF between sessions but the control unit should remain powered for MESSAGING 
and other, unattended, functions. 
The VDU case contains the mains power supply which is an ASTEC 30 watt SMPS 
(Switched Mode Power Supply) card (types AA12630, AA12635, or similar) The 
colour monitor has its own power supply but the mono monitor is powered from the 
ASTEC card which has the following rating:- 
+5 volts 3 to 3.5 Amps 
+12 volts 1.5 Amps 
-5 volts 0.1 Amps 
The power supply can be connected for 115 or 240 volts, both +/- 10% and draws a 
nominal mains current af 0.75 Amps. 
The 9 inch mono monitor uses a Philip's Chassis and contains an ICL composite 
video board. Colour and mono monitors have LED (or neon) indicators for 'Mains 
ON' and 'Monitor Power ON' plus a contrast control. 
Power supplies and video signals are coupled from the monitor, via a multi-core 
cable, to a 15 way D plug on the control unit. 
2 VDU options were available when the OPD was introduced: 
A 9" white screen unit with levels of contrast matching the number of colours in 
a particular screen mode, or a 14" Microvitec colour monitor available in medium 
resolution with high resolution as a later option. 
Screen Format 
The screen format is similar to the QL. It is bit mapped and has 2 modes 
selectable from software:- 
256x256 pixels, 40 characters per line, 24 lines plus a 2 line 'Notice Board' at 
the bottom of the screen. Green, red and blue can be displayed on a colour 
monitor, giving 8 shades (contrast levelled plus flashing, on a monochrome 
512x256 pixels, 40 or 80 characters per line, 24 lines plus a 2 line 'Notice 
Board'. Red and green only are available on a colour monitor giving 4 shades on 
a monochrome monitor. 
In BASIC the screen size available as display for the running program is less 
than the gross figures quoted above e.g. in the 512x256 mode the BASIC program 
display area is only 480x200. 
This is a single RS423 serial port which is compatible with RS232 for printer 
duty. The port consists of a 9 way female D connector on the OPD control unit 
(only 3 pins of the connector are used). 
The ICL package printer was an OKI thermal, colour printer with a draft printing 
speed of 80 cps and 40 cps in NLQ. 
Epson RX80 compatible printers are catered for in the software and printer 
configuration programs. The normal BT Tonto printer is the Merlin M1880, 
described as a standard graphics printer The M1880 appears to be MOA printer 
MP1711 (WM80) and to be a Shinwa SP80 badged for BT. The MP1713 (WM100) DMP was 
also issued with some Tontos. 
The daisywheel printer recommended for the Tonto was the Dyneer DW16. 
The OPD has 2 batteries: BAT1 is a 9 volt, PP3, manganese battery which backs 
the telephone and the Real Time Clock. It is fitted under the microdrive cover 
and is user replaceable. The Operating System checks BAT1 voltage during 
power-up and under the HOUSEKEEPING function. BAT2 is a 3 volt lithium unit 
(with a life of at least 5 years) which backs the PERMANENT STORE CMOS RAM. It 
is soldered to the motherboard; is not considered user replaceable and is not 
checked directly by the Operating System. 
The 73 key keyboard is QWERTY layout with 10 of the keys colour coded to act as 
function keys and double as a 'telephone style' numeric pad. The keyboard is 
manufactured by ALPS using individual switches of rubber membrane construction. 
Keyboards with black QWERTY keys, and a red ENTER key, are export units intended 
for Australian. Keyboards in standard OPD/Tonto Colours but with inverted '' 
and '#' symbols, and 3 letter 'telephone' groups on the front faces of the 
number pad keys, are thought to be export units for North America. Later 
versions of the keyboard have blocking diodes on 5 keys. 
The ROMPACK included, as an option, XCHANGE in ROM. The original 2 slot ROMPACK 
has 5 off 32K ROMs. Later, 4 slot versions, and TELESTORE, use a high capacity 
ROM to make room for the additional slots. ROM capsules mount in the slots and 
can be 8, 16 or 32K. 
+5 volt supplies, address and data buses, plus READ/WRITE and EXTINT lines are 
available on the 30 pin 'slot' connectors to allow their use as a simple 
expansion ports. 
The ROM capsules are normally constructed on single sided PCB, with the ROM IC, 
a resistor and a supply decoupling capacitor surface mounted, to obtain minimal 
capsule thickness. The ROM IC must be de-soldered to remove it. 
A capsule's presence is signalled by a link on its 30 way connector which 
enables that 'slot's' section of the PLA de-coding (in the ROMPACK). Capsule 
ROMs have a specific firmware header which the OS checks at Power-up The System 
verifies that the capsule ROM is a valid OPD device and, if valid, 'logs' it 
onto the OS. (Detail of capsule construction is given in Appendix 5). 
The OPD is made up of 4 units: 
Control Unit 
VDU and Power Supply 
The control unit includes the main PCB, 'piggy-back' CPU board, keyboard, 
telephone hookswitch, loudspeaker, 2 batteries and 2 microdrives. 
The telephone handset is wired directly to the modem. The modem and the ROMPACK 
plug into the rear of the Control unit. 
The monitor includes the power supplies for itself and the other units. 
Control unit 440mm x 250mm x 95 mm 
Mono Monitor 250mm x 280mm x 280mm 
Control unit 3 kg 
Mono Monitor 4.15 kg. 
The OPD main board uses the 2 Sinclair QL ULAs (ZX8301 and ZX8302 or 
equivalents). Each microdrive uses a QL Ferranti/Sinclair 2GO075ES device. Two 
ICL 'ULAs' are employed. One is ULA3 on the main board which controls the non-QL 
functions i.e telephone, speech synthesizer, battery backed static RAM etc. The 
second ICL 'ULA' is the PLA device for address de-coding and interfacing in the 
[ 5 types of ICL PLA have been identified: 
KVAB02 - Standard 2-slot ROMPACK 
KVADO1 - Standard 4-slot ROMPACK 
KVAL01 - TELESTORE 4-slot 
The 4 and 6 slot TELESTORE use a PCML CMOS PLA ]. 
The Texas vocabulary ROM is an OPD special. The modem uses six thick film, 
hybrid circuits. Excluding Capsules there are ten ROM ICs in an original OPD 
with XCHANGE. Identified ICL ROMs are listed in Appendix 3. 
The design concept was that, for ease of operation, fast loading and 
optimisation of the relatively small RAM, the major applications programs would 
be provided in ROM. This was in keeping with the targeted, non-technical 
executive market. The intent being that the OPD would not rival a desk-top PC 
for general computing. The following ROM firmware was produced for the OPD: 
The OS is an ICL multi-tasking 'special'. up to 5 tasks can be run concurrently. 
It is not QL QDOS nor is it an industry standard which can take advantage of 
existing software. The OS is contained in 4 X 32K ROMs on the CPU board. A 
further 14K is carried in the ROMPACK. ICL called the OS 'BFS' (Basic Functional 
The following make up the BFS: 
KERNEL - manages the hardware, the memory map, input output device control, and 
also handles interrupts. 
DIRECTOR - is higher level firmware handling applications and the telephone. It 
controls START, RESUME and REVIEW key functions and allocates resources. 
TELEPHONE HANDLER - manages the 'nuts and bolts' of telephone usage. 
TELEPHONE DIRECTORIES - 2 directories are managed, one for telephone voice calls 
and one for computer services. CALCULATOR - A simple 16 digit calculator with 
memory. (CALCULATOR firmware is in the ROMPACK). 
SCREEN IMAGE PRINTER - A screen dump to printer on a single keystroke. 
FIELD EDITOR - provides cursor and text editor control. 
The PSION standard package (Quill - word processor: Archive - database: Easel 
business graphics and Abacus - spread sheet) is provided in ROM, as an option, 
and mounts in the ROMPACK. Version 2.5 was in service by mid 1985 but surplus 
units are generally the earlier version 2.3. On entering XCHANGE from the 
APPLICATIONS menu the version number is displayed. In general the 2-slot 
RROMPACK has version 2.3 and the 4-slot ROMPACK, TELESTORE and the MEU have 
version 2.5. 
2.3 DATALINK (BT Reference M1824) 
A single capsule introduced to overcome, in part, the isolation of the XCHANGE 
programs from the communications facilities. It allows incoming communications 
data (from a computer service or mainframe) to be imported, 'via microdrive', to 
XCHANGE. It also allows QUILL format files to be exported, 'via microdrive', by 
the communications facilities of the OPD. 
2.4 MESSAGING (BT Reference M1821) 
A single capsule which provides desk-to-desk text messaging between OPDs; 
unattended receipt; auto-send; dump to microdrives and a print or resend option. 

2.5 ADVANCED MESSAGING (BT Reference M1822) 
An expansion of MESSAGING which occupies 2 capsule slots, providing all the 
facilities of Messaging plus auto-retry; multiple addressing and an interface 
facility with EXPORT format files. 
2.6 INTERFILE (BT Reference M1823) 
Occupies 1 capsule slot allowing file transfer from OPD-to-OPD via the modem. 
Facilities include auto-retry and transmission at pre-set times. The INTERFILE 
ROM includes 'patch' code to permit more than 6 ROM applications to be connected 
to the OPD at the same time. 
Occupies l capsule slot, allowing communication with ICL mainframe computers and 
emulation of a full XBM Screen Mode Terminal. ICL-LINK requires a Desk Terminal 
Connection Unit (DTCU) for the link interface. 
2.8 VT-LINK/VT-LINK 2 (BT References M1825/M1826) 
Occupies 1 slot and provides terminal emulation for communication with Digital 
Equipment Corporation (DEC) VT series computers. VT-LINK covers VT52 and VT100 
emulations. VT-LINK 2 covers the VT52, and VT102. Its manual states it also 
covers VT100. VT-LINK 2 includes an improved printer configuration program 
CONPRIN allowing condensed 132 column printing in some applications. This 
CONPRIN can conflict with the disk based CONFIGURATION programs supplied for 
2.9 ILLUSTRATOR EGO (Executive Graphics Option) 
Occupies 1 capsule slot, allowing connection of an QPD to an ICL mainframe (via 
ICL-LINK, and a DTCU ) to view professional graphics on the OPD. Graphics may be 
viewed and stored on microdrive but cannot be altered or edited by the OPD. 
Combines the functions of ICL-LINK, VT-LINK and TERMILINK in a single capsule. 
2.10.1 ICL-LINK is for general ICL computers, providing emulation of a full XBM 
Screen Mode Terminal. It requires a Desk Terminal Connection Unit for 
2.10.2 VT-LINK provides terminal emulation of the DEC VT52 and VT100. 
2.10.3 TERMILINK provides terminal emulation for the ICL 6402 and 6404 QUATRO 
series desktop computers. 
COMBINED COMMS. is incompatible with VT-LINK 2. If both are fitted to the 
ROMPACK at the same time the OS will log-on only the VT-LINK * program with the 
lowest memory address. (Both programs have the same name viz ~DD). 
2.11 DB-LINK 
A Capsule from MGB Micro Products which allows the OPD to auto-log-on and 
auto-answer when used in conjunction with the MGB Dialback Security System. 
2.12 MGB-LINK 
A capsule from MGB Micro Products including all the facilities of DB-LINK plus 
the ICL-LINK terminal emulation package (2.7 refers). 
An upgraded version of ACTION DIARY from Satellite Computing 
A computer access page store with enhanced facilities including archiving, 
organising and merging of stored pages and self-running displays. 
A Satellite Computing Romcap linking Basic programs and the telephone. 
A Satellite Computing Romcap providing a graphics display system for producing 
transparencies and designing, and running, flipchart style presentations using a 
rolling, on-screen display. 
A 3 capsule set from Computer One was scheduled for release in mid-1986. The 
Compiler was in 2 capsules and the Assembler in one. These were to be supplied 
with a 4-slot ROMPACK containing XCHANGE with QUILL being used to prepare and 
edit programs. 
This also was from Computer One and intended for release as a special ROMPACK 
assembly. XCHANGE was not available with this ROMPACK but the system included an 
editor for program preparation. 
3.1 ICL OPDBASIC (BT MERBASIC Reference M1851) 
BASIC is not resident in the OPD. It is loaded from microdrive and is a subset 
of Sinclair QL SuperBASIC. It lacks SuperBASIC features especially graphics. (In 
multi-tasking, there is insufficient memory to store several complete graphics 
screens and recall them with the RESUME and REVIEW keys). 
ICLBASIC was intended as a high level bridge to QL software but, as such, it has 
limited capabilities. BASIC version 07 was available in 1986. The version in use 
can be displayed by the PRINT VER$ command. The early Basic versions included 
features which were discontinued in later versions e.g. Ver. 5.02 includes 
Tokenised SAVE and PUBLISH commands TK_SAVE and TK_PUBLISH respectively. These 
allow Basic programs to be saved in a coded form with a table of keywords and 
commands. This increases the length of small and medium files but can reduce 
programme loading times by factors up to 3. 
The BASIC cartridge contains the factory-set default values of the PERMANENT 
STORE plus configuration programs for the OPD, the printer and the telephone 
(CONFIG, CONPRIN and CONTEL respectively). 
[ Unlike the QL the OPD ROM and cartridge formats are similar making it possible 
to transfer the ICLBasic interpreter to EPPOM. The file length of version 05 
BASIC is approximately 38K. Version 07 is shorter ]. 
3.2 ICL WELCOME (BT Reference M1850) 
This cartridge was supplied as part of the WELCOME package to provide 
information and to demonstrate the equipment's capabilities to the new user. 
3.3 ICL/PSION - HELP (BT Reference M1854) 
HELP files for the XCHANGE programs are provided as a microdrive cartridge. 
3.4 ICL - DEMO (BT Reference M1853) 
A demonstration program for XCHANGE including a '.dbf' file on geography for 
working through ARCHIVE. 
These relate to the OPD as released in 1984. The references in brackets refer to 
subsequent introductions of hardware, or software, to correct, or reduce, the 
identified deficiency. 
4.1 Serious memory shortage and fragmentation of the available memory as the 
work session proceeds.(5.1 and 5.2 refer). 
4.2 PSION XCHANCE is not integrated with the Operating System. QUILL cannot 
access the modem or the real time clock etc.. (2.3 refers). 
4.3 BASIC is not in ROM and has to be loaded from microdrive, absorbing scarce 
PAM. (Memory expansion of 5.1 and 5.2 refer; see also the note in 3.1). 
4.4 Multi-tasking is limited by memory shortage and the Operating System e.g. 
in-coming telephone calls can abort Operations in progress such as microdrive 
formatting. (Memory expansion of 5.1 and 5.2 refer). 
4.5 The Operating System is an ICL 'special', So preventing the use of standard 
software. (The CP/M facilities of 5.2.1 refer). 
4.6 ICLBasic is a curtailed subset of Sinclair SuperBASIC but is not compatible 
with it e.g. ICLBasic does not include SuperBASIC graphics such as LINE, CIRCLE 
and ARC. 
4.7 The standard mono monitor is not of high quality. It has no brightness 
control, in consequence, the display can be difficult to optimise. (The optional 
colour monitors provide an improved display and are preferred by most business 
4.8 PSION XCHANGE, in ROM, is not fully developed and is inflexible regarding 
update and improvement by third party software e.g. QUILL cannot be modified for 
spelling checkers and cursor acceleration programs such as SPELLBOUND, FILEBOUND 
and TURBOQUILL+ while ARCHIVE cannot save the faster '_pro' programs. 
4.9 The numerical routines for access by menu, together with the hierarchical 
menu structures, are cumbersome and lack mnemonics or similar logical features 
to help the operator remember them. 
4.10 The keyboard has a number of multi-function/shifted keys; some keytops 
having 3 legends. 
4.11 Device names, such as the microdrives, change between normal OPD operation 
and operation in BASIC. 
4.12 An OPD (with 4 ROM capsules) can have over 400K of firmware in ROM (14 ROM 
ICs). This yields benefits in speed and simplicity of operating but up-dating to 
later, improved versions of the firmware can be expensive when PROMs rather than 
re-programable EPROMs are used i.e. new ROM devices have to be obtained and the 
old devices discarded. [ In general early OPDs used EPROMs but the bulk of the 
main OPD production used PROMs. ] 
4.13 Many of the OPD functions have a raw, unfinished feel as if they needed 
refining to reach release standard. 
The OPD was not provided with a dedicated expansion port. The ROMPACK connector, 
or a ROMPACK capsule slot, is used to link expansion hardware to the internal 
The connector on the main board, for the ROMPACK, (J5) is provided with a 
variety of interface connections which are not used by the ROMPACK (or fed 
through it) but can be used for comprehensive expansion if the ROMPACK is not in 
place. The socket pin-out is shown in Fig. 2. 
The memory map makes provision for only 128K of RAM expansion (256K total DRAM). 
A disk interface can include more RAM, generally in RAMDISK configuration, by 
incorporating a dedicated processor to manage the RAMDISK and the disk drives 
yet absorbing no more than one 32K slot on the OPD memory map. 
5.1.1 MEU 
ICL developed a 128K Memory Expansion Unit (MEU) [sometimes called a Store 
Expansion Unit (SEU)]. This was intended to be the main unit of an ICL expansion 
system. It had a slow RS232 port (for bar code reading, printers etc.), 4 
capsule slots, a RESET button and a 60 pin expansion port. The MEU was large, 
approximately 10.5"x 7.2"x 1.5". The case was steel with a plastic overcover. 
Connection to the OPD was via a 6 inch length of ribbon cable and a modified 
ROMPACK case containing line drivers and receivers. 
The MEU memory duplicates the basic arrangement in the OPD and is controlled by 
a ZX8301 with a 12Mhz crystal. The address lines to the ULA are modified to 
position the memory at the expansion addresses. Two 74HCT2S7s provide DRAM 
address multiplexing and a 74HCT245 acts as the data bus transceiver. The memory 
itself uses four 256K DPAM ICs (81464 devices, each 64Kx4 bit). 
The serial port is based on the RCA CDP65C51E1 IC with a 1.8432 Mhz crystal. 
XCHANGE version 2.5 is provided in two PROMs. A third ROM, a 27C64-25 EPROM, 
carries firmware to initialise the new memory and service the RS232 port. 
Two PLA devices provide the overall addressing and interfacing. The MEU design 
was bulky and expensive. When PCML produced the smaller, cheaper TELESTORE, ICL 
terminated the MEU and adopted TELESTORE as the official memory expansion for 
the OPD. 
The PCML 128K memory expansion, TELESTOPE, fits into a ROMPACK case. The 
original version had 4 'slots' plus version 2.5 of XCHANGE. A later, 1987 
version, was built into an extended case and accommodated 6 capsules (in single 
line outwards from the case). 
PCML designed the TELESTORE with a fairly standard ROMPACK base board plus a 
'piggy-back' board containing the extra memory. Unlike the standard ROMPACK the 
main components are soldered into the board to cut down height and allow the 
assembly to fit into the standard case. The 'piggy-back' memory board is mounted 
on a 34 way, in-line header strip. 
The 128K memory is 4 off 4464 ICs (64K x 4 bit each), controlled by a Toshiba 
TC17G014AP-12 CMOS gate array which is custom programmed and uses a 12 Mhz 
crystal. The 'piggy-back' board also contains two 74HCT257 address multiplexers 
and a DIL resistor network. 
The base board contains 2 PLA devices, buffers and XCHANGE 2.5 in two ROMs. The 
ROMs are the ICL/PSION XFAA01 and a 27C512 EPROM containing the remainder of 
XCHANGE plus the initialisation firmware for the extra memory. 
Both the MEU and TELESTORE included special initialisation and checking firmware 
for the memory expansion. When an OPD is powered-up with TELESTORE (or the MEU 
connected) the screen displays that an 'Invalid Capsule' is present and 
HOUSEKEEPING shows the standard free store capacity of about 150 blocks. The 
special initialisation routine then checks and logs-on the new memory and the 
updated HOUSEKEEPING Store Report shows the increased memory of about 400 
blocks. This extra process takes about 15 seconds and does not cause 
illumination of the line LEDs, as in the normal initialisation. 
5.2.1 Computer One 
Computer One supplied disk drives and an interface. This consists of a inverted 
'L' shaped interface which plugged directly into a ROMPACK slot. The interface 
connected via a 34 way ribbon cable to a standard disk drive unit with an 
internal torroidal transformer power supply. 
The circuit was a relatively standard 10 IC arrangement built round a WD1772 IC. 
The disk unit could have 1 or 2 x 3.5 inch DS/DD drives (720K formatted 
capacity/drive) or, optionally, 5.25 inch drives could be provided. The disk 
format was claimed as MSDOS but a single sample of the interface was tested. It 
would not read standard 3.5 inch disks from PCs or the TELEDRIVE neither would 
the interface write to disks formatted on other MSDOS machines. Similarly PCs 
and PC compatibles could not read disks from the interface. 
The interface failed to gain the acceptance achieved by TELEDRIVE and is no 
longer advertised. 
As an extension to their previous work on QL disk interfaces, PCML developed 
TELEDRIVE, a dual, 3.5 inch disk drive unit with 720K per drive formatted 
capacity and a MSDOS operating system. The use of MSDOS allows TELEDRIVE to 
exchange disks with PCs; see Appendix 4. The unit has 256K of DRAM (part of 
which can be configured as RAMDISK) and its own HD64180 (CMOS Z80) processor. It 
connects to the OPD via a ROMPACK capsule slot, is self-powered by a linear 
power supply and has provision to accept a further two external, Shugart 
compatible drives. 
Two RS232 ports for computer to computer communications were intended for later 
versions but no sign of this facility has been seen in the field. In 1986 PCML 
intended to expand further to include a 10Mb hard disk with a SASI interface. 
The status of this is unknown. 
[Part of the 256k of memory is required to service the interface. l80K. remains 
available for RAMDISK but this reduces to 72K if CP/M is running.] 
The overall size is 10.6" long x 4.3" x 4.1" . 
To run the late issue PCML disk programs and CPM the 27256 TELEDRIVE EPROM must 
be Version 2.0 or later. CP/M is not an emulation but CP/M running concurrently 
Early model TELEDRIVES had a weakness in their power supply which could allow 
some disk drives to pull the 5 volt rail to-the electronics below acceptable 
operational limits. This caused the two disk drives to run simultaneously and 
lock in that condition. The fault can corrupt data on the disks and in extreme 
cases disk and drive damage can occur. 
Three PCML software packages were produced for the TELEDRIVE: CP/M OPERATING SYSTEM 
This allowed CP/M+ (version 3.0, 56K TPA) to be run on the OPD, via the disk 
drive, and so take advantage of CP/M commercial and public domain software. The 
CP/M system includes two disks; a LOADEP and a the CP/M system disk. The 
pre-release version provides three CP/M disk formats (Superbrain, QX10UK and 
QX10US). This allowed import of programs from other CP/M machines. The QX10 
formats were allocated to drives C and D. To implement their use extra drives 
had to be provided or the internal selection links altered in drive B. 
On the final CP/M version the system disk contains programmes to import and 
export files between the normal TELEDRIVE MSDOS format and CP/M. This permits 
program material to be provided from PD libraries, or similar, on standard MSDOS 
3.5 inch disks. TELETOOLKIT 
A general utilities disk for inspecting and altering the content of files. The 
later versions of TELETOOLKIT included improved versions of the configuration 
programs. TELELOADER 
Allows the standard top level menu to be replaced by a menu offering up to 20 
This was provided for the Tonto by BT. It connects via a ROMPACK capsule slot, 
is powered from the OPD and provides outputs (via a 25 way, female D connector) 
which are compatible with RS232C, RS423 and CCITT V24 standards. Emulation of 
the following terminal types is possible: DEC VT52 and VT100 (80 column mode 
only) and IBM 3278 via a suitable protocol converter. Baud rates from 50 to 9600 
can be configured from software. 2400 is the recommended rate. 
The ACU was designed, by ICL, as part of the MEU expansion system and offers 
speeds of up to 19200 bps by, optionally, by-passing the OPD's integral modem, 
so allowing high speed communication and networking under control of one of the 
terminal emulation programs. Canadian Standards and ULA approvals were obtained 
and the unit was still available from ICL, in early 1988. 
This unit's program is called a LOCAL COMMS. CONFIGUPATOR and allows profiling 
of port parameters and operation by ACU or by modem. The ACU was designed to 
compliment the MEU, was contained in a steel case approximately 4.5"x 10.5"x 
1.5" and powered from the OPD, either direct from a ROMPACK slot or, 
alternatively, it could sit on the MEU fed from that unit's 60 way expansion 
port. The ACU 'footprint' is the same as the TELEDPIVE's. 
The ACU has a single 25 way D connector, RS232C port based on an 'intelligent', 
Intel P80C31BH processor with a 7.37280 Mhz crystal. A series of 74HCT257 
multiplexers allow control to be taken over from the OPD, by the P80C31. 
Firmware is provided in 2 EPROMs (a 27C256 and a 27C64). A small ASTEC 
encapsulated SMPS is 5 powered from the +5 voLt rails to generate standard 
RS232C port voltages which are not available via the ROMPACK slot (i.e. +12 and 
-12 volts). Two 2K CMOS RAM ICs provide buffering for data. 
Transmission and reception speeds can be specified separately in the range from 
50 to 19200 bps. Other adjustable parameters are word length, parity, input and 
output buffer sizes buffer filling and emptying levels, X-ON and X-OFF and flow 
Profiles/patterns for various port configurations can be set-up, stored in the 
OPD PERMANENT STORE and recalled for particular applications 
A free standing, self-powered, adaptor for connecting OPDs, running ICL-LINK, to 
ICL SME or TME mainframe computers at speeds up to 9600 bps. Full XEM (ICLC-03) 
terminal emulation is provided with dual screen capability and auto-answer from 
the OPD. The DTCU microcode (E13100/01) is teleloaded from the mainframe. 
A free standing, self-powered unit that works with VT-LINK to provide OPD to IBM 
mainframe communications. Full screen working to the IBM host is available at 
speeds up to 9600 bps together with access to the host's applications. Security 
features are included with auto-answer from the OPD. 
5.7 DATEX 90 
This provides simultaneous voice and data communications on a single telephone 
This can connect the OPD to ICL DRS series computer systems via DRS model 110. 
Allows files to be transferred between OPDs and IBM PCs. 
5.10 TELEBOX 3 
Allows the OPD to be used as a Telex station 
A security device produced by PCML. It consists of an in-line plug/socket 
assembly which plugs into the 2 'D' connectors on the OPD control unit (the 
supplies/video and the printer connectors) and provides 2 new 'D' connectors, at 
its outboard end, for the original leads. There is a lock on the unit operated 
by a Yale type key. The OPD can be disabled, for security purposes by locking 
and removing the key. 
BT produced a tilt and swivel stand for the mono monitor. 
The following list is not exhaustive: 
Computer One produced a Microsoft compatible BASIC COMPILER and INTERPRETER 
providing performance improvements of 3 to 4 over OPD Basic. (2.18 refers). 
Computer One also offered a 'C' COMPILER and ASSEMBLER. (2.17 refers). 
Produced by Computer One. 
Metamco supply a cross-development package which allows OPD software to be 
developed on an ICL or IBM PC. 
6.5 CHESS 
This is available from PSION for the OPD with 28 levels of play. 
A small business accounting package from A.M. Programmers. 
Superplant Software offer a database system which uses ARCHIVE to help with tree 
and plant selection and care. 
Satellite Computing produce an ACTION DIARY. 
This is produced by Satellite Computing. 
 These are produced by: 
D.J. Walker, 22, Kimptons Mead, Potters Bar, Herts., EN6 3HZ Tel. 0707 52791 
They consist of a QL/OPD FILE INTERCHANGE program and a QL/OPD DIRECT I/Q 
TOOLKIT. The same author produces the DISCOVERY programme which allows disks to 
be interchanged between the QL and PC compatables. This programme allows the QL 
to write to disks that the TELEDRIVE can read. 
A program for creating special spreadsheet templates for income tax, budgeting, 
financial reports etc. Patrick and Leach. 
A program to simplify basic ARCHIVE application which the user can then tailor 
to his individual needs. It requires XCHANGE vers. 2.5. and is available from 
Ark Distribution. 
A business forecasting program from Control-C Software. 
A cut down version of WordStar for use with the TELEDRIVE disk unit running 
A program from Control-C Software for jotting down ideas which can be refined at 
a later date. 
7.1 BOOKS 
Century Communications Ltd. (Newtech Publishing Ltd.) produce 3 guides to the 
'Merlin-Tonto' at a listed price of 12.95 each. These books are user orientated 
and contain no significant technical detail of the internals of the 'Tonto'. 
They are: 
"Business Communications with the Merlin Tonto" by Martin Gandoff ISBN 0-09 
"Introducing the Merlin Tonto" by Garry Marshall ISBN 0-09-161661-1 
"Business Computing on the Merlin Tonto" by Stephen Morris ISBN _0-09-161671-97 
7.2 REVIEWS The OPD was reviewed, or discussed, in the following periodicals: 
'Personal Computer World' December 1984 
'Which Computer?' February 1985 
'Practical Computing' January 1985 
'Practical Computing' April 1985 
'Micro Decision' February 1985 
'Byte' June 1985 
'Computing - The Newspaper' July 18, 1985 
'Communications' November 1985 
'Accountancy' June 1986 
'Surveyor' January 1985 
'Computing Magazine' April 25, 1985 
'Informatics' December 1984 
The OKI printer, OKImate 20, was reviewed in 'Practical Computing' May l985. 
ICL issued a quarterly newsletter 'OPD - Today' which was distributed free to 
official users. The last issue was July 1987. 
The following user manuals were provided by ICL or BT: 
Installation'(BT Reference TPU 12A)
            'Handbook' (BT Reference TPU 12B)
            'Basic'(BT Reference TPU 12C) 
            'MESSAGING'(BT Reference TPU 12D) 
            'Xchange'(BT Reference TPU 12E)
            'Welcome Package'(BT Reference TPU 12F) 
            'Advanced Operations'(BT Reference TPU 12G) 
            'Installing Telephone Lines and Sockets'(BT Reference TPU 12H) 
            'INTERFILE'(BT Reference TPU 428) 
            'VT-LINK 2'(BT Reference TPU 730) 
            'COMBINED COMMS.' 
            'EGO ILLUSTRATOR'(Leaflet only) 
            'Exchange quick reference' (BT Reference TPU 192) 
            'MP1887 DATACOMMS ADAPTOR'(BT Reference TPU 116) 
            'XCHANGE QUICK REF. CARD'(BT Reference TPU 242) 
            'M1880 PRINTER MANUAL'(BT Reference TPU 249) 
            'M1881J2 PRINTER MANUAL'(BT Reference TPU 332) 
            'OPD VT100 LINK'(BT Reference TPU 334) 
            'USING MP11881 WITH TONTO'(BT Reference TPU 439) 
            '14 INCH COLOUR MONITOR'(BT Reference TPU 17J) 
            'MERIN TONTO Some Questions and Answers'(BT STAFF ONLY) 

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