Barq AQ-900
This page was last modified 21:27, 17 January 2022 by Mars2000you.

Contents

Description

The Barq AQ-900 is a re-branded Spectravideo SVI-838, also known as X'press 16, for the Arabic countries. Two stickers were used to hide partially the original brand. It was probably sold with an Arabic keyboard.

Although this machine is an IBM PC clone with CGA graphics, it also includes same video co-processor as MSX2 and MSX sound compatible PSG on system board. With separately sold SVI-811 Game Adapter it is possible to extend this machine to be partially MSX compatible game console. For more MSX related information, please see SVI-811 page.

Notes:

  • Specially modified GW-BASIC 3.2 (see below) was included with the system that gave somewhat limited access to extended sound and video chip capabilities.
  • Alternatively it was possible to use video co-processor VRAM as RAM disk or printer buffer by using drivers delivered with the machine.

AQ-900 peripherals

  • QS-113: Joystick
  • QS-119: Joystick
  • SVI-109P: Quickshot IX joyball
  • SVI-110P: Quickshot X joystick (probably provided with the AQ-900)
  • SVI-811: Game Adapter
  • SVI-812: Multifunction card (adds 384kB RAM, RS-232C, RTC)
  • SVI-813: Cooler
  • SVI-814: PAL RF Adapter (to color TV or RGB monitor)
  • SVI-815: Monitor cable (D15 to 21 pins adapter, to RGB monitor)
  • SVI-816: Monitor cable (D15 to 8 pins adapter, to digital/analog RGB monitor)
Brand Barq (Manufacturer: Spectravideo)
Model AQ-900
Year 1986
Region Middle East
Launch price
RAM 256kB, expandable to 640kB
VRAM 128kB for V9938, 16kB for V6355 (CGA video chip)
Media 5.25" 360kB floppy disks - With SVI-811: MSX cartridges
Video Yamaha V6355 (CGA) with superimposition over V9938 (MSX2 VDP!)
Audio AY-3-8912 28-pin PSG, PC Speaker
Chipset
Keyboard layout QWERTY/Arabic probably
Extras One or two 5.25" 360kB disk drives (or a drive and a 20MB hard disk drive), superimposing, probably Quickshot X joystick (not MSX compatible), enhanced version of GW-BASIC
Emulation SVI-838 ROM dumped, mainly for archival purposes. It is unknown if this can be emulated.

Gallery

Barq AQ-900
Barq AQ-900 back
Barq AQ-900 right side
Barq AQ-900 underside
Barq AQ-900 label
Barq AQ-900 close-up
Barq AQ-900 without front sticker

Specifications

The AQ-900 is a PC clone with an Intel 8088 CPU running at 4.77 MHz, but has also the PSG and VDP, making it a hybrid system, with even an enhanced version of GW-BASIC.

Additional or modified GW-BASIC instructions for sound and graphics

  • COLOR background color
  • NOISE channel, periode, duration to use the PSG noise channel
  • PAINT x,y, paint attribute, border color, background attribute
  • PLAY with music macro language for each of the 3 PSG channels
  • SCREEN mode, burst, active page, visible page, clear screen, superimposition
  • SOUND frequency, tempo, volume, channel
  • SOUND OFF to select the PC generator sound
  • SOUND ON to select the PSG and use PLAY in similar fashion to Tandy and PCjr computers

Connections

  • RGB connector for monitor (DB-15)
  • Analog sound & Composite video (B/W)
  • Keyboard connector
  • Centronics compatible Parallel port for a printer
  • PC Mouse / Light Pen connector
  • Game connector for the provided PC joystick
  • ISA compatible expansion slot (for SVI-811A, SVI-812 or 3rd party expansion card)

I/O Device map

I/O Device SVI-838 SVI-811
8237A-5 DMA chip 000-00F
8259A Interrupt 020-021
8253-5 Timer 040-043
8255-5 PPI 060-063
DMA Page Registers 080-083
NMI Mask Register 0A0-0AF
Game Control 200-20F
Paraller Printer 378-37F
V9938 3C0-3C3 98-9B
PSG 3C8-3CA A0-A2
V6355 3D0-3DF B0-B7
Disk 3F0-3F7

Tips n' tricks

Due to fact that CGA graphics are superimposed over V9938, in order to play Japanese/USA games on original 60Hz frequency both V9938 and V6355 need to be changed to 60Hz mode.

60Hz pseudocode:
AQ-900: OUT #3C1,#80:OUT #3C2,#89:OUT #3DD,#65:OUT #3DE,1
(SVI-811: OUT #99,0:OUT #99,#89:OUT #B5,#65:OUT #B6,0)

50Hz pseudocode:
AQ-900: OUT #3C1,#82:OUT #3C2,#89:OUT #3DD,#65:OUT #3DE,9
(SVI-811: OUT #99,2:OUT #99,#89:OUT #B5,#65:OUT #B6,8)

External links