Oric

Controller and DOS architecture for Oric computers

Oric was the name used by Tangerine Computer Systems for a series of home computers, including the original Oric-1, its successor the Oric Atmos and the later Oric Stratos/IQ164 and Oric Telestrat models (model names stylized in upper case).

With the success of the Sinclair ZX Spectrum, Tangerine's backers had suggested a home computer and Tangerine formed Oric Products International Ltd to develop and release the Oric-1 in 1983. Further computers in the Oric range were released through to 1987 with Eastern European clones being produced into the 1990s.

Models

Oric-1

Oric-1

Based on a MOS 1 MHz 6502A CPU, the Oric-1 came in 16 KB or 48 KB RAM variants for £129 and £169 respectively, matching the models available for the popular ZX Spectrum and undercutting the price of the 48 KB version of the Spectrum by a few pounds. The "48 KB" Oric-1 version was actually 64 KB. The top 16 KB of memory are masked by the BASIC ROM and thus normally not available for the user; The optional disc drive unit contains some additional hardware that allows it to enable or disable the ROM, effectively adding 16 KB of RAM to the machine. This additional memory is used by the system to store the Oric DOS software. Both Oric-1 versions had a 16 KB ROM containing the operating system and a modified BASIC interpreter.

During 1983, around 160,000 Oric-1 computers were sold in the UK, plus another 50,000 in France (where it was the year's top-selling machine). Although not quite the 350,000 predicted, this was enough for Oric International to be bought out and given sufficient funding for a successor model, the Atmos.

The Oric-1 improved somewhat over the ZX Spectrum with a different keyboard design replacing the ZX Spectrum's unusual Chiclet keyboard. In addition the Oric-1 had a true sound chip, the programmable GI 8912, and two graphical modes handled by a semi-custom ASIC (ULA) which also managed the interface between the processor and memory. The two modes were a "LORES" (low resolution) text only mode (though the character set could be redefined to produce graphics) with 28 rows of 40 characters and a "HIRES" (high resolution) mode with 200 rows of 240 pixels above three lines of text. Like the Spectrum, the Oric-1 suffered from attribute clash—albeit to a lesser degree in HIRES mode, when a single row of pixels could be coloured differently from the one below in contrast to the Spectrum, which applied foreground and background colour in 8×8 pixel blocks. As it was meant for the home market, it had a built in television RF modulator as well as RGB output and was meant to work with a basic audio tape recorder to save and load data. Error-checking of recorded programs was bugged, frequently causing user-created programs to fail when loaded back in. An additional feature was a Centronics compatible printer interface.

Oric Atmos

Oric Atmos

In late 1983 the funding cost for continued development of Oric caused external funding to be sought, and eventually led to a sale to Edenspring Investments PLC.^[1] The Edenspring money enabled Oric International to release the Oric Atmos, which added a true keyboard and an updated V1.1 ROM to the Oric-1. The faulty tape error checking routine was still there. Soon after the Atmos was released, the modem, printer and 3-inch floppy disk drive originally promised for the Oric-1 were announced and released by the end of 1984. A short time after the release of the Atmos machine, a modification for the Oric-1 was issued and advertised in magazines and bulletin boards. This modification enabled the Oric-1 user to add a second ROM (containing the Oric Atmos system) to a spare ROM-socket on the Oric-1 circuit board. Then, using a switch, the users could then switch between the new Oric Atmos ROM and the original Oric-1 ROM.

Oric Stratos and Oric Telestrat

Oric Telestrat

Although the Oric Atmos had not turned around Oric International's fortunes, in February 1985, they announced several models including the Oric Stratos/IQ164. Despite their backers putting them into receivership the following day, Oric was bought by French company Eureka, which continued to produce the Stratos, followed by the Oric Telestrat in late 1986. In December 1987, after announcing the Telestrat 2, Oric International went into receivership for the second and final time.

Technical specification

Keyboard 57 moving keys with tactile feedback. Full upper and lower case with correctly positioned space bar. Full typewriter pitch. Key layout is standard computer type with ESC, CTRL, RETURN and additional cursor control keys. All keys have auto repeat.

Display Will drive a PAL UHF colour or black and white television receiver. Approximately Channel 36. RGB output also provided on DlN socket with 270° configuration.

Screen — Character Mode (Memory Mapped) 28 lines of 40 characters producing display very similar to Teletext. Character set is standard ASCII which is enhanced by the addition of 80 user definable characters. ASCII characters may also be re-defined as these are down loaded into RAM on power-up. Serial attributes are used to control display features, as in Teletext, and take up one character position. All remaining characters on that line are affected by the serial attribute until either the line ends or another serial attribute.

Display features are:-

a. Select background colour (paper) from one of eight.

b. Select foreground colour (ink) from one of eight.

c. Flash characters on and off approximately twice a second.

d. Produce double height characters (even line top, odd line bottom).

e. Switch over to user definable characterset. This feature is used to produce Teletext style colour graphics which does not require any additional RAM to operate.

Available colours are Black, Blue, Red, Magenta, Green, Cyan, Yellow and White.

Each character position also has a parallel attribute, which may be operated on a character by character basis, to produce video inversion. The display has a fixed black border.

Screen — Graphics Mode (Memory Mapped) 200 pixels vertically by 240 pixels horizontally plus 3 lines of 40 characters (same as character mode) at the bottom of the screen to display system information and to act as a window on the user program while still viewing the graphics display. Can also be used to input direct commands for graphics and see effect instantly without having to switch modes. Graphics display operates with serial attributes in the same way as characters except that the display is now considered as 200 lines by 40 graphics cells. Each graphic cell is therefore very flexible by having 8 foreground and 8 background colours and flashing patterns. The video invert parallel attribute is also usable in this mode. ASCII characters may be 'painted over' the graphics area thus enabling the free mixing of graphics and text.

Sound Uses internal loudspeaker and amplifier and can also be connected to external Hi-Fi system via a DIN connector. A three channel sound synthesizer (The General Instrument 8912) as used in arcade games machines which can produce musical notes from sub-sonic to supersonic frequencies. Envelope of sound output is programmable and can be used to synthesize various musical instruments.

Pseudo Random Noise generator (providing a hissing sound can be mixed into each channel). Provides interesting sound effects for video games.

Sound Commands Three tones can be produced directly from the keyboard.

a. A high beep when an alphanumeric key is pressed.

b. A low beep when a special key is pressed (e.g. Delete, Carriage Return).

c. A bell tone when the control G key is pressed.

The user can switch these sounds off as desired. There are four preprogrammed sound commands for use within programs. These are:—

i) PING, produces a bell-like tone, is also used as control G tone.

ii) SHOOT, simulates a gunshot.

iii) EXPLODE, creates the sound of an explosion.

iv) ZAP, produces a space-invader 'laser' sound. To facilitate the creation of other sounds there are three general purpose commands:

SOUND, MUSIC and PLAY. SOUND has a range of 15 Hz to 62 kHz. MUSIC will play notes within a seven octave range. Up to 3 voices can be used at one time.

Cassette Interface Connect via DIN socket. Uses Tangerine format which has been field proven over

4 years and thousands of systems. Operates at super reliable 300 baud or reliable super fast 2400 baud. A tone leader allows tape recorders' automatic level control to stabilise before first recording filename and then dumping program/data with parity. At the end of recording several check sums are recorded which will be checked on loading to verify correct operation.

A Schmitt trigger circuit is used on the tape input to remove noise. The Tangerine format is so good it is the one other manufacturers are copying. AII types of information may be saved such as programs, data, arrays, blocks of memory screen displays. After saving, correct recording may be verified before deleting information in memory. Remote motor control of tape recorder is provided; essential for the loading and saving of data files.

Available commands are CLOAD, CSAVE (for programs and memory dumps) STORE, RECALL (for arrays). Both programs and arrays may have a filename up to 16 characters. Arrays may be string integer or real. Various command extensions can be used such as S for slow speed, V for verify (CLOAD and CSAVE only) AUTO for autorunning of programs. A and E for start and end of memory dumps.

Expansion Port and Micro Drive Interface Full data, address and control information forthe6502A Micro Processor; for connection of add-ons. Can also be used for user designed hardware interfaces. Useful control lines allow RAM and ROM to be externally expanded (ideal for adding ROM cartridges).

Printer Port Standard Centronics parallel interface allows connection of a multitude of different types of printer from very cheap thermal types to high speed matrix printers or wordprocessors quality daisywheel printers.

Peripherals

Colour printer

Tangerine's MCP-40 is a plotter with mechanics by Alps Electric. The same mechanism was also used as the basis for similar low-cost plotters produced by various home computer manufacturers around that time. These included the Atari 1020, the Commodore 1520, the Tandy/Radio Shack CGP-115,^[2] the Texas Instruments HX-1000 and the Mattel Aquarius 4615.^[3]

Prestel adaptor

The Prestel adaptor produced by Eureaka (Informatika) was the first adaptor produced for the Oric-1 and Oric Atmos computers. However this adaptor was only furnished with very limited software, which was not suitable for the market at that time. John Henry Patrick Rushton was rumoured to have hacked the circuit - by meticulously removing the 'security compressed resin' surrounding the circuit board - and apparently discovering the 6522 and its workings. It is also believed that this is why he had taught himself 6502 assembly language (for the purpose of writing the necessary software, that a local software-house had refused to write for him, when requested ). It was then in 1983, that the first fully comprehensive communications software for both the Oric-1 and Oric Atmos was produced (Oricoms and Atcoms - distributed by FGC Publications of Euxton, Preston, U.K.). This software, designed and coded by Rushton and the accompanying manual (which was written by Trevor F Shaw) - both of Telford, Shropshire - utilised the 6522 ACIA (Asynchronous Communications Interface Adaptor, which served as a I/O port controller for the 6502 family of microprocessors). This software (the first of its type for the Oric series of computers and was indeed one of the early pioneers of home computer communications) enabled the Oric-1 and Oric Atmos to communicate with the Prestel videotex system, with Bulletin Boards and facilitated the transfer of files from one Oric-1/Atmos to another, via the public telephone system. The transfer speeds being either 300 or 1,200 baud (this could occur at both full and half duplex). Rushton was later - in the spring of 1984 - to produce the first (for the Oric-1 and Atmos) 'true' high resolution Computer Aided Design (CAD) utilities known as Oricad and Atcad respectively.

Clones

Pravetz 8D

A Yugoslavian company obtained a licence to make just 5,000 machines. Machines were made, but whether they were under license or not is not known in any detail. It is thought that they assembled parts shipped from the UK. They were Atmos based, the only difference being the logo indicating ORIC NOVA 64 instead of Oric Atmos 48K. Nova had 64 KB of RAM, 16 KB of which was masked by the ROM at startup, leaving 48 KB to work with the BASIC language.

A Bulgarian machine called the Pravetz 8D was produced between 1985 and 1991. The Pravetz is entirely hardware and software compatible with the Oric Atmos. The biggest change on the hardware side is the larger white case that hosts a comfortable mechanical keyboard and an integrated power supply. The BASIC ROM has been patched to host both a Western European and Cyrillic alphabet – the upper case character set produces Western European characters, while lower case gives Cyrillic letters. In order to ease the use of the two alphabets, the Pravetz 8D is fitted with a Caps Lock key. A Disk II compatible interface and a custom DOS, called DOS-8D, were created in 1987-1988 by Borislav Zahariev.

See also

• Category:Oric games
• Tangerine Computer Systems

References

External links

• Oric.org – The main Oric community portal
• The Oric FAQ – For Microtan 65, Oric 1, Oric Atmos & Stratos IQ164/Telestrat; website by James Groom
• Oric World – Including an online version of the book by Haworth
• Oric Atmos review – By David Scobie, Your Computer, March 1984 (text stored at the Home Computer Hall of Fame)
• Microtan 65 – Oric-1 – Oric Atmos – At the Old Computers Museum
• Defence-Force: Oric page – By Mickaël Pointier
• The Oric-1 is 30 years old – "The Register" article