🇬🇧 BBC Master Compact: Part 1 (Dusting it off) [TCE #0541]
52The BBC Model B was the first vintage computer system that I was really interested in (apart from the Amstrad CPC series), but they are yet to feature on the channel! I have a bunch of Model Bs and just one Master system ... a Master Compact.
00:00 ... Intro
02:33 ... Checking the ports
04:30 ... Checking the motherboard
07:10 ... Initial power on check - NOK
10:00 ... Closer look at the motherboard
12:58 ... Checking the Service Manual
15:15 ... Yeah, you can skip this
17:00 ... Checking the 16MHz oscillator
20:32 ... Crystal replaced, dodgy RCA connector
21:02 ... Power on test again
22:40 ... Channel outro & thanks
The Master Compact is a cutdown version of the Master 128 that had the computer contained within the keyboard and a separate unit containing the 3½" drive and power supply. The keyboard was connected to the unit by a 5V power cable and a DB25 cable for the disk drive.
Some further info here:
https://chrisacorns.computinghistory.org.uk/Computers/MasterCompact.html
You can run the machine with just a +5VDC power supply with 2.1mm plug (centre positive) - probably a modern USB charger is enough.
The major chips on the board:
6522: Versatile Interface Adaptor (VIA)
VC2069: Video ULA (or VIDPROC)
HD6845: CRT controller (CRTC)
SAA5050: Teletext character generator
CF30048: CRTC Multiplexer
CF30049: Peripheral Bus Controller
CF30050: I/O Controller
CF30058: Memory Controller (socketed)
WD1772: Floppy Drive Controller (FDC)
65C12: CPU
PCD8572: 1Kbit (128x8bit) EEPROM (socketed)
There are some empty sockets for the RS232 serial support. ECONET support comes via a daughterboard that plugs into the motherboard.
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