The boards are described as if you were viewing them from the component side with PL4 to the right.
Note:
+ indicates the standard link connection, as supplied.
* indicates a signal is active low
Link area 1. Base Address selectionLK1H select if A4 low + LK1G select if A5 low + LK1F select if A6 low LK1E select if A7 low LK1D select if A8 low LK1C select if A9 low LK1B select if A10 low LK1A select if A11 low |
Link area 1.o A o o B o o C o o D o o E o o F o o G o o H o |
Standard jumpering as shown above gives a base address of F90 (hex) or 3984 (decimal). Note that some operating systems may not access this board at the standard address. You MUST check with the appropriate software manual.
LK1 sets up the standard base address of the SG84 in STE I/O space. The standard base address is F90 (hex). Inserting a jumper on link 1 means the board will only respond if that address line is low, omitting a jumper means the board will only respond if that address line is high.
Table 1. Address Weights
LK1 Address Hex Dec Line
H A4 10 16 G A5 20 32 F A6 40 64 E A7 80 128 D A8 100 256 C A9 200 512 B A10 400 1024 A A11 800 2048
Link 2. DATACK* to STEbus+ LK2 DATACK* goes to STEbus Remove this link only when the test connector is being used. |
Link 2.o o |
Link areas 3 and 4. Interrupt and DMA Attentlon request outputsLK3A Interrupt request output on ATNRQ0* LK3B Interrupt request output on ATNRQ1* LK3C Interrupt request output on ATNRQ2* LK3D Interrupt request output on ATNRQ3* |
Link area 3.o A o o B o o C o o D o |
LK4A2 Interrupt request output on ATNRQ4* LK4B2 Interrupt request output on ATNRQ5* LK4C2 Interrupt request output on ATNRQ6* LK4D2 Interrupt request output on ATNRQ7* LK4A1 DMA transfer request output on ATNRQ4* LK4B1 DMA transfer request output on ATNRQ5* LK4C1 DMA transfer request output on ATNRQ6* LK4D1 DMA transfer request output on ATNRQ7* |
Link area 4.o A1 o A2 o o B1 o B2 o o C1 o C2 o o D1 o D2 o |
Link area 5. On-board/external master clock+ LK5A Normal operation using the on-board oscillator LK5B Master clock from external video source |
Link area 5.o A o B o |
Note: there must always be a source of master clock, otherwise the ACRTC will be damaged.
Links 6, 7, and 8. Analogue RGB output signal terminationLK6 75R termination on analogue red signal LK7 75R termination on analogue green signal LK8 75R termination on analogue blue signal |
LK7 o o LK6 o o LK8 o o |
Link area 9. IC17 Screen blanking optionLK9A ACRTC 'flash' option blanks video output (TTL monitors) + LK9B video output blanked during palette write cycles (analogue monitors) |
Link area 9.o A o B o |
Links 10, 13, 17-19. TTL/Analogue video output to PL4LK10 PL4 pin 6 is TTL Intensity output Link areas 10-19+ LK13A PL4 pin 5 is Analogue blue output LK13B PL4 pin 5 is TTL blue output + LK17A PL4 pin 8 is HSYNC output LK17B PL4 pin 8 is CSYNC output LK17C PL4 pin 7 is CSYNC output + LK18A PL4 pin 4 is Analogue green output LK18B PL4 pin 4 is TTL green output + LK19A PL4 pin 3 is Analogue red output LK19B PL4 pin 3 is TTL red output Link areas 11,12, 15 and 16. Signal optionsLK11 Make for positive TTL Hsync pulses + LK12 Sync superimposed on analogue RGB LK15 Make to invert TTL RGBI outputs LK16 Make for positive TTL Vsync pulses Link area 14. External sync routing+ LK14A1 External sync out to PL4 + LK14A2 External sync from ACRTC LK14B1 External sync from PL4 LK1482 External sync in to ACRTC |
LK14o A1 o B1 B2 o A2 o o 15 o o 16 o o 17A o o 10 17B o o 17C o o 11 o o 18A o o o 12 18B o o o o 19A 13A o o 19B 13B o o |
The default link settings have been chosen to suit the majority of monitors. Those that have been tested with the SG84 are listed below, with link adjustments where necessary.
Analogue/Digital RGB. Accepts several different sync. standards.
Analogue/Digital RGB. Positive syncs, not superimposed on analogue RGB.
Monochrome. Composite video input.
Default Sony Philips Zenith (Analogue, multisync multimode monochrome -ve syncs) CDP-1402E CM8873 ZVM-123-E
Ana, TTL Ana, TTL LK6,7,8 - In x - x x LK10 - x In x In x LK11 - - x x - x LK12 In - - In In x LK13,18,19 A A B A B x LK15 - - - - - - LK16 - - - - - - LK17 A A A A A x
- Link out x Dont care