Deramp Altair 8800c, Manual

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Altair Bus Signals
Pin Signal Description Pin Signal Description
1 +8v 51 +8v
2 +18v 52 -18v
3 XRDY Another RDY signal OR'd to 8080 53 SSWDSB* Direct sense switch input to the processor
4 VI0* Vectored interrupts 0-7 54 EXTCLR* Return all slave boards to known state
5 VI1* 55 RTC 60hz for Real-Time Clock
6 VI2* 56 STSTB* Status strobe
7 VI3* 57 DIG1 Data input gate 1 (for 8800b front panel)
8 VI4* 58 FRDY 8800b Front panel RDY to 8080
9 VI5* 59
10 VI6* 60
11 VI7* 61
12 62
13 63
14 64
15 65
16 66
17 67 PHANT* Not used in Altair
18 SDSB* Status disable (sMEMR, sWO, sM1, sINP, sOUT, sHLTA) 68 MWRT Memory Write (pWR* asserted and not SOUT)
19 CDSB* Control disable (pSYNC, pSTVAL, pDBIN, pWR, pHLDA) 69 PS* Memory protect status (out from addressed card)
20 UNPROT Front panel memory unprotect operation 70 PROT Front panel memory protect operation
21 SS Front panel single-step 71 RUN Machine is in the RUN state
22 ADSB* Address bus disable (A15-A0) 72 pRDY RDY signal OR'd with others to 8080
23 DODSB* Data Out bus disable (DO7-DO0) 73 pINT* Interrupt request to 8080
24 PHI2 Phase 2 clock 74 pHOLD* Hold request to 8080
25 PHI1 Phase 1 clock 75 pRESET* Reset line from from front panel reset switch
26 pHLDA 8080 hold acknowledge output 76 pSYNC 8080 start of machine cycle
27 pWAIT 8080 wait acknowledge output 77 pWR* 8080 write data valid
28 pINTE Asserted when the 8080 has interrupts enabled 78 pDBIN 8080 reading data bus
29 A5 79 A0
30 A4 80 A1
31 A3 81 A2
32 A15 82 A6
33 A12 83 A7
34 A9 84 A8
35 DO1 85 A13
36 DO0 86 A14
37 A10 87 A11
38 DO4 88 DO2
39 DO5 89 DO3
40 DO6 90 DO7
41 DI2 91 DI4
42 DI3 92 DI5
43 DI7 93 DI6
44 sM1 Machine cycle #1 (instruction fetch) 94 DI1
45 sOUT Write cycle for an OUT instruction taking place 95 DI0
46 sINP Read cycle for an IN instruction taking place 96 sINTA Bus cycle is interrupt acknowledge
47 sMEMR Read cycle is a memory read 97 sWO* Bus cycle is a write (memory or I/O)
48 sHLTA 8080 halt acknowledge output 98 sSTACK Bus cycle is a stack operation
49 CLOCK* 99 POC* Power on clear
50 GND 100 GND
Ground in IEEE-696 bus spec