8-Bit Software

The BBC and Master Computer Public Domain Library

Inside The Master 128

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IC1

7406 TTL 14/0-3

IC2

7438 TTL 14/0-3

IC3

WD1770 FDC 5.25''

IC4

74LS174 TTL 16/0.3

IC5

71lLS244 LL 20/0-3

IC6

6522 VIA NM0S 1MHZ

IC7

74LS373 LL 20/0-3

IC8

6522 VIA NM0S 1MHZ

IC9

LM324 QUAD 0P AMP

IC10

71lLs259 LL 16/0.3 option 74ALS259 LL 16/0.3

IC11

6818 RTC CM0S

IC12

761189 S0UND GEN

IC13

IC LM386 AUDIO AMP

IC14

65C12 CPU CM0S 2MHZ

IC15

MSI I/0 CTRL (CF30050)

IC16

MSI KEYBD ENC (CF3001l7)

IC17

4464 DRAM 120nS 64Kx4

IC18

4464 DRAM 120nS 64Kx4

IC19

74LS14 TTL 14/0.3

IC20

MSI MEM SW (CF30058)

IC21

MSI P.B.C. (CF300119)

IC22

68115 CRTC NM0S 1MHZ

IC23

4464 DRAM 120nS 64Kx4

IC24

EROS 1MB ROM

IC25

74LS86 TTL 14/0.3 option 74ALS86 TTL 14/0.3

IC26

4464 DRAM 120nS 64Kx4

IC27

SKT IC 28/0.6 NORM

IC28

74F74 LL 14/0.3

IC29

74HCT253 CM0S 16/0.3

IC30

74LS257 LL 16/0.3 option 711ALS257 LL 16/0.3

IC31

MSI CRTC MUX (CF3001l8)

IC32

SAA5050 CHTR GEN

IC33

74HCT253 CM0S 16/0.3

IC34

74S00 TTL 14/0-3

IC35

Empty

IC36

74F00 TTL 14/0.3

IC37

SKT IC 28/0.6 NORM

IC38

74LS00 TTL 14/0.3 option 74ALS00 TTL 14/0.3

IC39

74LS02 TTL 14/0.3

IC40

CF30060

IC41

SKT IC 28/0.6 N0RM

IC42

VIDEO PROCESSOR

IC43

74S04 TTL 14/0.3

IC45

6850 ACIA NM0S 1MHZ

IC46

LM324 QUAD 0P AMP

IC48

SERIAL PROCESSOR

IC49

7002 ADC 12 BIT

IC50

3691 RS422/423 DRVR

IC51

9637A RS422/423 RCVR

Keyboard

General description:- 93 keys are provided. 92 of these are in a modified 8 x 13 matrix as shown in figure 5. A keyboard encoder, IC16 is used to scan the keyboard. During idle (free run) mode, pressing any key will cause an IRQ to be generated via the system 6522. A connection is provided from IC16 to a 6522 'CA' type connection. Hence the interrupts thus generated are controlled by the 6522 control register. Depression of either of the shift keys, or the control key does not cause an interrupt to occur.

Keys are arranged as a QWERTY style keyboard with extra keys for a numeric keypad. Ten additional 'function keys' together with cursor control buttons, etc., are provided.
The "BREAK" key will reset the CPU and abort any access to the clock/RAM chip. To prevent accidental operation, a mechanical lock is provided. This is a plastic cam which is rotated through 90 degrees to stop the keytop from being depressed.

Keyboard Operation:- During free run mode, the keyboard column lines are continually scanned by incrementing a counter, decoding its outputs and pulling low a column line. Any key depressed will cause the interrupt to be generated. A signal, KeyBoard ENable is generated to stop free running mode. The counter contents are now loaded by CPU operation to determine on which row the key was pressed. The rows are then individually selected to determine which key was pressed.

LK12

3w WAFR 0.1 ST PCB
Plug, made B (East): CSYNC/Cartridge Machine Detect.

Two position link.

Position A - This connection to the computer CSYNC line is provided for
GENLOCK purposes.

Position B - Certain hardware cartridges may need to detect whether they are plugged into a Master Series computer or an Acorn Electron. Master computers are shipped with this link in the B position, causing a logic LOW to appear on pin A10 of the cartridges. The Electron has no connection to this pin.
9 Issue 1

LK18

3w WAFR 0.1 ST PCB

plug, made West: Paged ROM/RAM Select.

Two position link.

When fitted in the West position, this link causes 16Kbyte of RAM to appear in each of the "sideways" memory "slots" 6 and 7.

When fitted in the East position, a 32Kbyte ROM occupying slots 6 and 7 may be plugged into socket labelled IC41.
10 Issue 1

LK19

3w WAFR 0.1 ST PCB
plug, made West: Paged ROM/RAM Select.

Two position link.

When fitted in the West position, this link causes 16Kbyte of RAM to appear in each of the "sideways" memory "slots" 4 and 5.

When fitted in the East position, a 32Kbyte ROM occupying slots 4 and 5 may be plugged into socket labelled IC37.

MD1

MODUL UHF PAL WB E36

PAL/NTSC encoded, UHF carrier On channel 36 with 1.5mV into 75 ohm.

For use with NTSC, the modulator. has to be changed from UM1233/E36 to a VHF equivalent. Provision is made for selection of either one of two channels with V.H.F. A Molex type link has to be inserted for this.

PSU

The power supply unit is connected to the main circuit board by seven push-on connectors which must be unplugged. Three screws on the underside of the case are undone allowing the unit to be removed. On reassembly, ensure that the same type of screw is used (M3x6mm).

IDC Connectors
All IDC connector pins are numbered in this way:

PL1

34w HDR IDC RA 4 WALL 2
Disc Drive
1 0V 2 (notS/SEL 8'' )
3 0V 4 (notINX 8'')
5 0V 6 NC
7 0V 8 notINX 5 1/4"
9 0V 10 notS0
11 0V 12 notS1
13 0V 14 NC
15 0V 16 notMOTOR
17 0V 18 notDIR
19 0V 20 notSTEP
21 0V 22 notW/DATA
23 0V 24 notWR/EN
25 0V 26 notTK0
27 0V 28 notWR PCT
29 0V 30 notR/DATA
31 0V 32 notS/SEL 5 1/4"
33 0V 34 (notRDY 8")

PL3

26w HDC IDC RA 4 WALL
Printer
1 STB 2 0V
3 PA0 4 0V
5 PA1 6 0V
7 PA2 8 0V
9 PA3 10 0V
11 PA4 12 0V
13 PA5 14 0V
15 PA6 16 0V
17 PA7 18 0V
19 ACK 20 0V
21 NC   22 0V
23 NC   24 0V
25 NC   26 NC

PL4

20W HDC IDC RA 4 WALL
User Port
1 +5V 2 CB1
3 +5V 4 CB2
5 0V 6 PB0
7 0V 8 PB1
9 0V 10 PB2
11 0V 12 PB3
13 0V 14 PB4
15 0V 16 PB5
17 0V 18 PB6
19 0V 20 PB7

PL5

34w HDR IDC RA 4 WALL 2
1MHz Bus
1 0V 2 R/notW
3 0V 4 1E
5 0V   6 notNMI
7 0V   8 notIRQ
9 0V   10 notPGFC
11 0V 12 notPGFD
13 0V   14 notRS
15 0V   16 audio in/out (see LKl)
17 0V   18 D0
19 D1   20 D2
21 D3   22 D4
23 D5   24 D6
25 D7   26 0V
27 A0   28 A1
29 A2   30 A3
31 A4   32 A5
33 A6   34 A7

PL6

110w HDR IDC RA 4 WALL
Tube
1 0V   2 R/notW
3 0V   4 2E 5 0v
6 notIRQ 7 0V
8 notTUBE 9 0V
10 notRS 11 0V
12 D0   13 0V
14 D1   15 0V
16 D2   17 0V
18 D3   19 0V
20 D4   21 0V
22 D5   23 0V
24 D6   25 0V
26 D7   27 0V
28 A0   29 0V
30 A1   31 +5V
32 A2   33 +5V
34 A3   35 +5V
36 A4   37 +5V
38 NC   39 +5V
40 NC

PL8

3w WAFR 0.1 ST PCB

PL9

2W WAFR .1 RA PCB

PL10

5W WAFR 0.1'' RA 11PIN

PL17

TAB 6.3mm ST PCB

PL18

TAB 6.3mm ST PCB

PL19

TAB 6.3mm ST PCB

PL20

TAB 6.3mm ST PCB

PL21

TAB 6.3mm ST PCB

PL22

TAB 6.3mm ST PCB

PL23

TAB 6.3mm ST PCB

RL1

RLY 1P C0 5V 50R PCB
Cassette Relay

SK1

12W SKT HSNG 0.1 PCB
Expansion Board Slot

SK2

12W SKT HSNG 0.1 PCB
Expansion Board Slot

SK3

12W SKT HSNG 0.1 PCB
Cartridge Slot

SK4

12W SKT HSNG 0.1 PCB
Cartridge Slot

SK5

19w SKT HSNG 0.1 PCB
Econet Board Slot

SK6

5W SKT HSNG 0.1 PCB
Econet Board Slot

SK7

5W SKT DIN RA PCB
Econet Din Plug
Econet Plug

SK8

BNC SKT 75R PNL
BNC Video Out

SK9

6w SKT DIN RA PCB
RGB
RGB Socket

SK10

5W SKT DIN RA D0M
RS423
RS423 Socket

SK11

7w SKT DIN RA PCB
Cassette
Cassette Socket

SK12

15W SKT D RA E2.84
Analogue in
Analogue in Socket

1 +5V
2 0V
3 0V
4 CH3
5 analogue ground
6 0V
7 CH1
8 analogue ground
9 light pen strobe (notLPSTB)
10 digital switch input (I1)
11 voltage reference (VREF)
12 CH2
13 digital switch input (IO)
14 voltage reference (VREF)
15 CH0

SK13

PHONO SKT RA PCB
Audio Out

PSU

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