Tano Dragon: Обзор домашнего компьютера

Home computer model

In the United States it was possible to purchase the Tano Dragon new in box until early 2017 from California Digital, a retailer that purchased the remaining stock.

BYTE wrote in January 1983 that the Dragon 32 "offers more feature for the money than most of its competitors", but "there's nothing exceptional about it". The review described it as a redesigned, less expensive Color Computer with 32K RAM and better keyboard.

The Dragon is built around the Motorola MC6809E processor running at 0.89 MHz. It was an advanced 8 bit CPU design, with limited 16 bit capabilities. It was possible to increase the speed of the computer by using POKE 65495,0 which accelerated the ROM resident BASIC interpreter, but temporarily disabled proper functioning of the cassette/printer ports. Manufacturing variances mean that not all Dragons were able to function at this higher speed, and use of this POKE could cause some units to crash or be unstable, though with no permanent damage. POKE 65494,0 returned the speed to normal. POKE 65497,0 pushed the speed yet higher but the display was lost until a slower speed was restored. The Dragon used the SN74LS783/MC6883 Synchronous Address Multiplexer (SAM) and the MC6847 Video Display Generator (VDG). I/O was provided by two MC6821 Peripheral Interface Adapters (PIAs). Many Dragon 32s were upgraded by their owners to 64 KB of memory. A few were further expanded to 128 KB, 256 KB, or 512 KB with home built memory controllers/memory management units (MMUs). A broad range of peripherals exist for the Dragon 32/64, and there are add ons such as the Dragon's Claw which give the Dragons a port that is hardware compatible with the BBC Micro's user port, though separate software drivers for connected devices must be developed. Although neither machine has a built in disk operating system (Compact Cassettes being the standard storage mechanism commonly used for machines of the time), DragonDOS was supplied as part of the disk controller interface from Dragon Data Ltd. The versatile external ports, including the standard RS 232 on the 64, also allows hobbyists to attach a diverse range of equipment. The computer featured a composite monitor port as an alternative to the TV RF output which can be used to connect the Dragon 32 to most modern TVs to deliver a much better picture. The Dragon used analogue joysticks, unlike most systems of the time which used simpler and cheaper digital systems. Other uses for the joystick ports included light pens. Tony Clarke and Richard Wadman established the specifications for the Dragon. The units had a robust motherboard in a spacious case, reminiscent of the BBC Micro, and so were more tolerant of aftermarket modification than some of their contemporaries, which often had their components crammed into the smallest possible space.

The Dragon's main display mode is 'black on green' text (the black was, in actuality, a deeper, muddier green). The only graphics possible in this mode are quarter tile block based. It also has a selection of five high resolution modes, named PMODEs 0–4, which alternate monochrome and four colour in successively higher resolutions, culminating in the black and white 256×192 PMODE 4. Each mode has two possible colour palettes – these are rather garish and cause the system to fare poorly in visual comparisons with other home computers of the time. It is also impossible to use standard printing commands to print text in the graphical modes, causing software development difficulties. Full colour, scanline based 64×192 semi graphics modes are also possible, though their imbalanced resolution and programming difficulty (not being accessible via BASIC) meant they were not often utilised.

First to market was a complete disk operating system produced by Premier Microsystems, located near Croydon. The system was sold as the "Delta" disk operating system; there was a proposal for Dragon to market this as an addon. Dragon did not enter into such an agreement and instead produced the DragonDOS system. The two systems were incompatible. Delta's lead in availability ensured that software was released in the format, whilst Dragon's "official" status ensured that it, too, gained software published in its format. This led to confusion and frustration, with customers finding they had either purchased a version incompatible with their setup, or that the software was only available for the competing standard.

The Dragon comes with a Microsoft BASIC interpreter in 16 KB of ROM. The BASIC appears to be nearly identical to Tandy Color Computer's Extended Basic with a few changes necessary to interact with the Dragon system. The Dragon has additional circuitry to make the MC6847 VDG compatible with European 625 line television standards, rather than the US 525 line NTSC standard, and a Centronics parallel printer port not present on the TRS 80. Some models were manufactured with NTSC video for the US and Canadian markets.