Gradiente Expert

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Gradiente Expert GPC-1
Also known asExpert XP-800
ManufacturerGradiente Eletrônica
Typehome computer
Release dateDecember 1985
Operating systemMSX BASIC, MSX-DOS, CP/M
CPUZilog Z80A @ 3.58 MHz
Memory64 KB–4096 KB (max.)
Removable storageCassette tape, cartridges, floppy discs
SuccessorExpert GPC-1

The Expert (or Expert XP-800), made by Gradiente Eletrônica (to date best known as a game console and Hi-Fi equipment company) was the second and last MSX home computer launched in the Brazilian market, in the mid-1980s.[1]

It was presented to the public at the 5th International Computing Fair, nicknamed "Informatica '85".[2] The event took place at Anhembi Convention Center in the city of São Paulo from September 23 to 29, 1985.[3] At the announcement, the computer was priced 65 ORTN s.[4]

Its market release date was 1 December 1985, one week after Epcom's Hotbit, just in time for 1985's Christmas and with a massive media campaign on magazines, newspapers and TV. In the newspapers ads the initial offer price was Cr$ 4,640,000, or US$ 470 by the value at the time,[5] or US$ 1,165 by the end of 2021.

The machine was a clone of the National CF-3000, with a computer case resembling a stereo system, a detached keyboard with a proprietary connector, no caps lock LED and no reset key,[1] although the soft-reset could be achieved by pushing in either of the cartridge slot covers.[6][7]

The Expert XP-800 was followed by the Expert GPC-1 ("Gradiente Personal Computer") in 1987, and by Expert Plus and Expert DD Plus (a system with a built-in 720 KB 312" floppy disk drive) in 1989.[8]

The Expert users waited for an MSX2 machine, but Gradiente never produced it[8] and discontinued the MSX line in 1990.

Versions XP-800/GPC-1[edit]

The two first versions had a graphite case and socketed chips, which caused a chronic problem: when the machine heated, the chips frequently pulled out and the system "froze". Also, the GPC-1, released in 1987, had a ROM slightly modified to solve an ASCII table compatibility issue with the other popular Brazilian MSX, Sharp's Hotbit.

Versions Plus/DD Plus[edit]

The last two versions had a black case and the problematic socketed chips were replaced by an ASIC. Nevertheless, the RAM was mapped to a secondary slot and, although it was straight by the MSX standards, caused a lot of crashes with programs who searched for memory in the wrong place. It did not contribute for the popularity of any of the Plus versions.[8]

These machines used the MSX-Engine T7937A instead of the Z80A CPU of previous models.

Technical specifications[edit]

CPU Zilog Z80A (XP-800 & GPC-1) @ 3.58 MHz
MSX-Engine T7937A (Plus & DD Plus) @ 3.58 MHz
Keyboard mechanic, 89 keys (with 4 cursor keys), number pad
Display text: 40×24 rows; graphics: 256×192 pixels, 16 colours, 32 sprites
Sound General Instrument AY-3-8910 (PSG), 3 voices, white noise
Ports 2 joystick connectors, TV out, RGB monitor out, sound out, tape recorder connector, parallel port, 2 cartridge slots
Storage tape recorder (1200/2400 bit/s) or one or two external floppy drives (514", 360 KB or 312", 720 KB)



  1. ^ a b "Gradiente Expert XP-800". Retrieved 2023-05-20.
  2. ^ "5ª Sucesu e 18º Cong. Nacional da Informática". Museu de Eventos - Anhembi (in Portuguese). 2015-05-18. Retrieved 2023-05-20.
  3. ^ "Uma Vitrine Renovada" (PDF). VEJA (in Portuguese). No. 891. October 2, 1985. pp. 88, 89.
  4. ^ "Informática 85: o que há de novo no setor" (PDF). Micro Sistemas (in Portuguese). September 1985. p. 36.
  5. ^ "BRENO ROSSI shop advertising". O Estado de S. Paulo (in Portuguese). No. 33.987. December 15, 1985. p. 24.
  6. ^ "Gradiente Expert XP-800". MSX Resource Center. March 8, 2023.
  7. ^ "Expert". Museu da Computação e Informática - MCI (in Portuguese). 2004.
  8. ^ a b c "GRADIENTE Expert Plus". OLD-COMPUTERS.COM.