Contents |
Description
The Expert GPC-1 was the second MSX1 model made by Gradiente, which fixed some issues of the previous model XP-800 (see Specifications section). GPC means 'Gradiente Personal Computer'.
Following the release of the GPC-1 on the market, Gradiente issued a free recall called "Conversion from 1.0 to 1.1", asking to owners of Expert XP-800 to take their machines to a service center. In a few minutes the EPROM and the 9 keys were substituted, free for the user.
Because of this, most of Expert XP-800 are found showing a 1.1 ROM version and modified keyboard.
| Brand | Gradiente |
| Model | Expert GPC-1 |
| Year | ??/1987 |
| Region | Brazil |
| Launch price | |
| RAM | 64kB in slot 2 |
| VRAM | 16kB |
| Media | MSX cartridges |
| Video | Texas Instruments TMS9128NL |
| Audio | PSG |
| Chipset | none (separate IC's) |
| Keyboard layout | QWERTY with a "ç" key + numeric keypad |
| Extras | built-in speaker with volume control, RGB output, demo cartridge called "Ligue-se ao Expert" |
| Emulation | ROM dumped and emulated. The shared 2nd cartridge slot with the rear expansion port is handled like a single MSX cartridge slots. |
Pictures
Specifications
The Expert GPC-1 is a rather complete MSX1, with full 64KB of RAM in slot 2. It has a Z80A from Zilog.
Slot Map
| Slot 0 | Slot 1 | Slot 2 | Slot 3 | ||||
|---|---|---|---|---|---|---|---|
| Page C000h~FFFFh | Cartridge Slot 1 | 64kB RAM | Cartridge Slot 2 + Expansion Bus | ||||
| Page 8000h~BFFFh | |||||||
| Page 4000h~7FFFh | Main-ROM | ||||||
| Page 0000h~3FFFh |
Connections
- RF output (PAL-M)
- Video composite (PAL-M) and analog sound output
- Monochromatic video output
- RGB video output (DIN8, non-standard)
- non-standard keyboard connector
- non-standard Data Recorder connector
- non-standard Centronics compatible Parallel port for a printer
- 2 general connectors (Joysticks, Mouse, Paddle controlers, etc)
- 2 cartridge slots
- 1 expansion bus slot (that shares slot 3 with the second cartridge slot)
- 2 switched AC sockets
Modifications by comparison with the XP-800
Hardware Modifications
No modification was made to the digital PCB, but there are batches with IC sockets just for RAMs and LSI chips, and batches with no IC sockets at all.
The TA-1 TV adapter was embedded onto the machine case, meaning that the analog PCB was changed to provide a composite video output (PAL-M standard) and a RF output (VHF channel 3 or 4).
They also added a 6VDC supply output to power the DR-1 data recorder.
Software Modifications
The way of typing accented letters was changed to be exactly as like in a typewriter. And the codes of the Portuguese accented characters were changed to match a specification called "Brazilian ASCII", or BRASCII.
These modifications in ROM led to the version to be changed to 1.1. But this computer is known and often called by brazilian MSX users as "Expert 1.1" due to the hardware modifications.
Keyboard Modifications
Also, the positions of the accents and some characters were changed in keyboard layout, leading to 9 different keys between the layouts of the keyboard of XP-800 and GPC-1.
The issue of wearing-off the painted letters of the keyboard remained.