Chapter 1 1.3 Hardware overview 1.3.1 ACW 443 The ACW uses the National Semiconductor 32000 chip set, including the NS32016 Central Processing Unit ( CPU),the NS32081 Floating Point Unit (FPU) and the 32201 timing and control unit (TCU). These have a 32-bit internal architecture and use a 16-bit external data bus. The Workstation also contains a 6512 processor (an enhanced version of the 6502 processor), which acts as an input/output (I/0) processor and can also be used independently. In this case the Workstation acts as a BBC model B+ microcomputer with 64 Kbytes of memory. The ACW is supplied with the PANOS operating system kernel (PANDORA) installed on the 32016 card.
This provides PANOS with an access mechanism to the various BBC filing systems in the I/0 processor. 4M bytes of internal RAM memory are provided as standard on the 32016 processor card, and a 700Kbyte 80- track floppy disc and a 20Mbyte hard disc storage is fitted on the model 443. Keyboard activity, the screen output, disc interface, network interface and other general I/O tasks are all handled by the 6512A processor, which has its own 64Kbytes of local RAM. An integral 12" medium-resolution colour monitor and a stand-alone keyboard complete the standard specification. A mouse controller, which fits inside the main case, is available as dealer installed optional upgrade.
1.3.2 Main unit The upper case, including the plastic screen surround moulding, or bezel, is removable. The chassis is of modular construction and opens to reveal a number of surfaces which can be easily serviced (See the section on disassembly for instructions) Field servicing should be on a module replacement basis, though socketed ICs may be changed whenever their breakdown is detected. The disc drives (floppy and Winchester) and the power supply module should always be replaced as a complete unit in the field. Note that the replacement of the monitor tube represents an implosion hazard and should not be undertaken in the field.
1.3.3 Power supply +5V output voltage 4.9 to 5.2V +12V output voltage 11.4 to 12.6V 1.3.4 Environmental Minimum operating temperature 0 degrees C Maximum operating temperature +37 degrees C Minimum storage temperature -30 degrees C Maximum storage temperature +60 degrees C Maximum operating humidity 80% RH at 35 degrees C Maximum storage humidity 80% RH at 55 degrees C Operating altitude 0 to 1800 metres above sea level Storage altitude 0 to 3500 metres above sea level Thermal gradient 10 degrees C per hour 6 ACW SERVICE MANUAL Issue I