Acorn Computers Limited BBC A Hardware Manual

15, 15 discharge is hardly worth considering recent research has proved otherwise. Recent investigations have revealed that damage caused to MOS and CMOS integrated circuits may not be immediately apparent, that is to say that the device may function perfectly satisfactorily but w…

33, 33 3.13 The User and Printer Ports. IC69 is a 6522 Versatile Interface Adapter (VIA) which is used to provide both a standard Centronics parallel printer interface and the user port on the BBC Microcomputer. The printer port uses lines PA~ to PA7 of this VIA, which are buffered by an octal 3…

47, Acorn Computers Limited BBC A 47 value of 300 ns and a maximum value of 0. Any attached peripheral device should, therefore, be able to cope with this. iv) The recommended method of connecting the peripheral device to the 1MHz bus is via a 600 mm length of 34 way ribbon cable terminated at each end with a 3…

46, 46 iv) Conduct a detailed visual inspection of the PCB's paying particular attention to those areas which have a high population of discrete components such as resistors and capacitors. These areas are mainly around the UM1233 video modulator in the NORTH EAST corner of the m…

25, 25 <Figure 3.2 to go here> PALETTE 64 BJT RAM (4x16) RGB FROM SAA5050 MULTIPLEXER CURSOR CONTROL RGB out FIGURE 3.2 RGB SYNTHESIS IN VIDEO ULA A feature of the BBC Microcomputer is its ability to perform a "hardware scroll". The start-address-r…

44, 44 Depending on the particular links that are to be modified it may be necessary to remove the keyboard in order to gain access. Links S4, 58, S10, S14, S17, S18, and S30 are those in question on boards up to issue 3. Boards from issue 4 onwards also have links S35, S36, S37 and S38 beneath the…