The model 820-II is basically a model 820 with a higher clock rate (4 MHz instead of 2.5 MHz) and a 8" double density/double side disk-drive and hard-disk instead of the the two basic 8" Single density/single side disk-drive of the first model 820. But the hard-disk is said to be very noisy and the dual disks weigh more than 38 pounds!
Nearly all the hardware is housed within the monitor, a bit like a Macintosh. The separate keyboard is linked to the monitor by a "not-long-enough" cord. The 8" disk-drive and hard-disk are mounted in a separate huge box. The 10MB hard drive for example was boxed with an 8" drive. A real-time clock is included in the hardware. Green screens were available in all models since the screen/processor case was common to all.
Like its predecessor, the 820-II is well furnished in software of all sorts. Thanks to its CP/M compatibility nearly every profession can find a suitable program. A lot of languages and OS were also available (CP/M, Basic 80, C Basic 2, Assembler Macro 80, Cobol 80, Short 80, TTY communication, 3270/3780 emulation).
But the 820-II has no real graphic possibilities nor sound, and a small RAM capacity (64 KB) for a professional computer. Above all it was quite expensive compared to its competitors.
There was also WP dedicated versions with unique key caps.
A 16-bit expansion board was released to upgrade the 820-II, so that its performance would nearly match the new Xerox computer(the 16/8), and also allowed the 820 to work under DOS. At the start of the year 1985, Xerox would definately leave the micro-computer market and stop the production of the 820.
简介编辑本段回目录
The Xerox 820 was an 8-bit desktop computer sold by Xerox. The computer featured floppy disk drives for mass storage, and used the CP/M operating system. The design of the microprocessor board was a licensed variant of the Bigboard computer.
The Xerox 820-II followed in 1982, featuring a Z80A processor clocked at 4.0 MHz. The units were priced starting at $3000.
Hardware: The processor board was located inside the CRT unit, and included the Z80A, 64K of RAM (with optional expansion up to 32-34K), and 6-8K of ROM (expandable).
Screen: The CRT itself was a 24-line, 80-character (7x10 dot matrix) white-on-black monochrome display, with software-selectable variations such as reverse video, blinking, low-intensity (equivalent to grey text), and 4x4-resolution graphics.
Communication ports These included two RS-232 25-pin serial ports (including one intended for a Xerox 620 or 630 printer or compatible) and two optional parallel ports which could be added via an internal pin header with either an official Xerox cable or one's own modification.
Keyboard: The keyboard was a bulky 96-character ASCII with a 10-key numeric keypad and a cursor diamond which otherwise defaulted to control characters 'A-D. It also included "Help" and "Line Feed" keys, and attached to the back of the CRT unit with a thick cable.
Software: An example 820-II would come with a copy of CP/M 2.2, a diagnostic disk, a copy of MicroPro's WordStar suite, and Microsoft's BASIC-80.
Although it may be confusing to users of modern computers, the CRT unit contained the processor, and a large port on the back connected via heavy cable to a disk drive, allowing a wide variety of configurations. Disk drives could even be daisy-chained to each other via a port on the back of a unit.
主要参数编辑本段回目录
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| NAME | 820-II |
| MANUFACTURER | Xerox |
| TYPE | Professional Computer |
| ORIGIN | U.S.A. |
| YEAR | 1983 |
| END OF PRODUCTION | 1985 |
| BUILT IN LANGUAGE | Basic 80 delivered on disk |
| KEYBOARD | AZERTY/QWERTY, full-stroke keyboard with separated keyboard, 74 keys |
| CPU | Z80A |
| SPEED | 4 Mhz |
| RAM | 64 kb |
| ROM | 8 kb |
| TEXT MODES | 80 x 24 (character matrix : 5 x 7) 12'' black & white monitor |
| COLORS | Black & white |
| SIZE / WEIGHT | Main unit / monitor : 32,8 x 38,1 x 34,3 cm / 13,6 kg |
| I/O PORTS | Serial 9600 bauds, Internal Expansion Slot, External Floppy Connector |
| BUILT IN MEDIA | one 8'' disk-drive (DD/DS) (320 KB) and one 8'' hard-disk (10MB). |
| OS | CP/M 2.2 |
| POWER SUPPLY | Built-in PSU |
| PERIPHERALS | Additional disk-drives, printer, modem, 16-bit board |
| PRICE | 9832  (France, 83) |
