Turn on your WayBack machine.
to about the dawn of time...
that is, the creation of the
Microprocessor.
Just after MITS Introduced its
Altair, A company called
SouthWest Technical products Company
introduces a computer kit called,
simply enough, the SWTPC (I am not sure
if the PC in the product name meant
"personal computer".) It features a 6800
(NOT 68000)processor and an SS-50 bus for periperhals.
SS-50 (SWTPC bus) pinout:
1
D0Data Line 0
2
D1Data Line 1
3
D2Data Line 2
4
D3Data line 3
5
D4Data line 4
6
D5Data line 5
7
D6Data line 6
8
D7Data line 7
9
A15Address line 15
10
A14Address line 14
11
A13Address line 13
12
A12Address line 12
13
A10Address line 10*
14
A9Address line 9
15
A8Address line 8
16
A7Address line 7
17
A6Address line 6
18
A5Address line 5
19
A4Address line 4
20
A3Address line 3
21
A2Address line 2
22
A1Address line 1
23
A0Address line 0
24-27
GNDGround
28-30
+8VSystem Unregulated 8V power
31
-12V-12 to -15 volts @ 1 Amp
32
+12V+12 to +15 volts @ 1 Amp
33
INDEXBoard seating pin( no connection)
34
MRSTManual Reset
35
NMINon Maskable Interrupt
36
IRQInterrupt ReQest(maskable)
37
UD2User Defined
38
UD1User Defined
39
02Phase 2 system clock
40
VMAValid Memory Address flag
41
R/WRead/Write cycle flag
42
RSTsystem ReSeT
43
BAAcknowledge DMA request
44
01Phase 1 System Clock
45
HALTDMA request to CPU
46
110110 Baud X 16 clock
47
150150 Baud X 16 clock
48
300300 Baud X 16 clock
49
600600 Baud X 16 clock
50
12001200 Baud X 16 clock
*: Where is data line 11???