Chapter 1: Overview; Key Features - Sinclair Q68 User Manual

Chapter 1: Overview

Key Features

The Q68 mainboard is a medium-performance Sinclair QL successor mainboard. It is based on a speciali-
zed chip, which includes both the CPU and the system controllers on a single integrated circuit. This chip
includes a 68000 compatible microprocessor, video controller and most system components.
Like the original QL mainboard, the Q68 is a complete solution including graphics, peripherals and sound.
It can be fitted into an available case. The Q68 does not need any parts from an existing QL, nor QL ex -
pansion or speedup cards.
Instead of the traditional QL mass storage devices, the Q68 has two SDHC card drives. The graphics re-
main compatible to the original QL, but add high colour and high resolution modes. Video output is suita -
ble for contemporary monitors. Peripherals are modernized, while the overall system maintains a high de-
gree of QL compatibility.
CPU
The microprocessor inside the Q68 is code compatible to the 68000, and runs at 40 MHz clock rate. In ad-
dition to the higher clock rate, many instructions are executed in less cycles than by a 68000. Unlike the
68000, it has a 32-bit address bus. If desired, the Q68 can slow down the system speed by hardware.
RAM
The Q68 has 32 MB of on-board synchronous dynamic RAM (SDRAM). 4 MB of this memory is dedicated
screen memory and not available for other purposes. Additionally, it has a small 12 KB static RAM
(SRAM) area which runs at higher speed.
ROM
The Q68 has a 96 KB ROM area at the start of the address range. This area is used by the integrated
bootloader, and also as ROM emulation for a loadable operating system.
Graphics
The Q68 has an integrated graphics controller with 16 bit colour and highspeed FIFO RAM. It works non-
interlaced in all modes, using dual / triple scan for the low resolutions.
Video modes
0. Standard QL MODE 8 256x256 pixel (8 colours)
1. Standard QL MODE 4 512x256 pixel (4 colours)
2. Q40/Q60 highcolour mode 512x256 pixel (65536 colours)
3. Q40/Q60 highcolour mode 1024x512 pixel (65536 colours)*
4. High resolution QL MODE 4 1024x768 pixel (4 colours)
5. Aurora mode 1024x768 pixel, 256 (colours)*
6. Medium resolution highcolour mode 512x384 pixel (65536 colours)
7. High resolution highcolour mode 1024x768 pixel (65536 colours)*
In all of the above modes, the output on the VGA connector is provided as a 1024x768 VESA standard si-
gnal for maximum PC compatibility.
Note: Due to memory bandwidth limitations, using the video modes 3, 5 and 7 slows down the system si-
ginficantly. The loss of speed is approximately 37%, 28% and 56%. These modes are not recommended
when speed is relevant.
For full speed, use the Standard QL video modes 0 or 1. In the remaining modes 2, 4 and 6 only a mini -
mal speed loss occurs in benchmark figures. This is not noticeable during normal use. These modes are
recommended as a compromise between colours / resolution and work speed.