Difference between revisions of "Aleste 520EX"

Revision as of 04:19, 11 February 2010

Aleste 520EX - a CPC clone housed in a case with MSX keyboard

The Aleste 520EX is a clone of the Amstrad CPC 6128 developed 1993 Patisonic in Omsk (Siberia). The Aleste is rare, according to Patisonic themselves, they "produced several dozens of the model, some of them was in 'kit' form".

Additionally to the standard CPC6128 features, it includes a number of extra features: 64-color palette, double color depth in slightly decreased horizontal resolution mode (eg. 16 color at 256x200 resolution), battery-backed Real Time Clock chip, 512Kbyte RAM (of which 192K can be accessed as on 64K CPC with 128K dk'tronics memory expansion), 8bit printer port, expanded keyboard matrix with 10 additional keys, two software controlled LEDs, extended Expansion Port (with additional pins for DMA support).

The computer works with Amstrad CP/M and MSXDOS as well (note: MSXDOS is a CP/M clone, which uses a FAT filesystem, as used on MSX and MS-DOS computers, instead of the normal CP/M filesystem).

Technical

• Aleste 520EX - I/O Ports - I/O Ports, Memory, etc.
• Aleste 520EX - Schematics - Schematics, Chipset, etc.
• Aleste 520EX - Expansions - Hardware Expansions, External Connectors, etc.
• Aleste 520EX - Software - Amstrad CPC and MSXDOS Software
• Aleste 520EX - Misc - Unsorted Notes

Amstrad Mode

Differences:

- Interrupts can't be manually cleared. This was possible on the CPC by writing to the Gate Array with data bit 7 set 1, bit 6 set to 0 and bit 4 set to 1. In the Aleste this bit is controls an LED.

- Decoding of it's equivalent of the Gate-Array is based on A15 only.

- The Aleste uses a patched CPC6128 Operating System ROM. It is patched to use the Aleste's 8-bit printer port and has a different startup message.

Special Mode

At this mode computer have different memory manager. The manager seems same like MSX mapper and could swicth ON any 16KB page of whole memroy at the any of 16KB page of CPU memory.

The mode have different color coding system. It has the color lookup table (CLUT) or another name pallette. That is dual port memory one prot for coversion pixel's color number to RGB levels. But second for CPU acccess. There is 2 bits for each channel at the pallette present, then it lets to have 64 colors.

The mode have two additional modes with 32KB of video memory. Pixel encoding the same as at Amstrad mode but each line has twice more bytes (and pixels). Two 16KB pages transfer to output, one buffer for odd and second even lines of screen.

The computer have also mc146818 compatible RTC and a 8251 compatible serial. A serial mouse can be used.

The 8253 timer is used to generate transmit and receive clock for serial. In addition the CURSOR output of the CRTC is connected as a trigger which is then connected to the colour hardware. So the CRTC cursor can be used to switch colours by the hardware.

Aleste ROM is 64KB:

• page 0 is modified Amstrad CPC6128 OS ROM
• page 1 is Amstrad BASIC
• page 2 is AMSDOS (Amstrad DOS)
• page 3 is Boot Rom, BIOS Setup, MSXDOS boot loader

The BIOS SETUP lets control over: date and time, boot drive, RAM disk, screen mode and style, printer, serial port, and mouse.

At the boot time computer loads BIOS and MSXBDOS (BIOS for Disc BIOS) from a bood disc. After that COMMAND.COM (MSXDOS). Computer can bott from RAM disc as well. Computer go to AMSTRAD mode when "Shift" is pressed while reset.

Pictures

• Pictures from http://aleste520.narod.ru
• 

  PCB and Keyboard

• 

  PCB top (component side)

• 

  PCB bottom (solder side)

• 

  PCB illustrated

The above photos are showing a more or less fully assembled Aleste (the LEDs are missing, and, more important, there is no connection for an internal or external power supply attached to the mainboard - unless the owner used the Expansion Port connector to inject power supply voltages).

• Pictures from http://www.zonadepruebas.com
• 

  PCB and Keyboard

• 

  PCB only

• 

  Rear-connectors

• 

  Bottom

This version has 7pin+7pin sockets for printer (normal would be 5pin+7pin, though the extra pins are most probably left unused).

Documents

• Media:Aleste-Programming-Manual-English.txt - original programming manual (english version, ported to ASCII format)

Technical specs

• CPU: Z80
• Clock: 4Mhz (CPC mode derived from a 16Mhz crystal), 3.2Mhz (Aleste mode derived from a 13Mhz crystal)
• Memory manager: Dk'Tronics compatible memory mapper (CPC mode), msx-mapper (Aleste mode)
• Memory: 512КБ (up to 2МБ)
• Audio: AY8910
• Graphics:
  • 256x212:16 colors
  • 512x212:4 colors
  • 320x200:16 colirs
  • 640x200:4 colors
  • 640x400:4 colors interleaved
  • Palette 64 colors
  • Hardware scroll (standard CRTC hardware scroll)
• Floppy disk 3.5"
• Mouse
• RTC (mc146818 compatible)
• Expansion slot
  • 19 address lines
  • DMA to whole memory
  • External board MagicSound
    • 4 channels
    • 8 bits per channel
    • Stereo output
• Touch screen (only prototype)
• Light-Processor with D54

Weblinks

• http://aleste520.narod.ru - site dedicated to aleste (mainly english, plus some russian docs)