This is a guide
to make a homebrew A601 without the RTC circuit.
Important notice: do it at your
risk! I am not responsible for damage to your Amiga, the hack itself or broken
marriages.
This hack add 1 MB of Chip RAM to your A600, regardless of what size SIMM you add, even 128Mb ones.
I will not provide a diagram or a printed circuit board. Make this hack at your full responsibility and own risk!
72 pin Fast Page Mode SIMM 256k/512k/1M/2M/4M/8M x 32/36 bit
Pin |
Assign |
Pin |
Assign |
Pin |
Assign |
Pin |
Assign |
Pin |
Assign |
Pin |
Assign |
Pin |
Assign |
Pin |
Assign |
1 |
GND |
10 |
Vcc |
19 |
A10 |
28 |
A7 |
37 |
MP1 |
46 |
N/C |
55 |
DQ11 |
64 |
DQ31 |
2 |
DQ0 |
11 |
N/C |
20 |
DQ4 |
29 |
N/C |
38 |
MP3 |
47 |
-WE |
56 |
DQ27 |
65 |
DQ15 |
3 |
DQ16 |
12 |
A0 |
21 |
DQ20 |
30 |
Vcc |
39 |
GND |
48 |
N/C |
57 |
DQ12 |
66 |
N/C |
4 |
DQ1 |
13 |
A1 |
22 |
DQ5 |
31 |
A8 |
40 |
-CAS0 |
49 |
DQ8 |
58 |
DQ28 |
67 |
PD1 |
5 |
DQ17 |
14 |
A2 |
23 |
DQ21 |
32 |
A9 |
41 |
-CAS2 |
50 |
DQ24 |
59 |
Vcc |
68 |
PD2 |
6 |
DQ2 |
15 |
A3 |
24 |
DQ6 |
33 |
-RAS3 |
42 |
-CAS3 |
51 |
DQ9 |
60 |
DQ29 |
69 |
PD3 |
7 |
DQ18 |
16 |
A4 |
25 |
DQ22 |
34 |
-RAS2 |
43 |
-CAS1 |
52 |
DQ25 |
61 |
DQ13 |
70 |
PD4 |
8 |
DQ3 |
17 |
A5 |
26 |
DQ7 |
35 |
MP2 |
44 |
-RAS0 |
53 |
DQ10 |
62 |
DQ30 |
71 |
N/C |
9 |
DQ19 |
18 |
A6 |
27 |
DQ23 |
36 |
MP0 |
45 |
-RAS1 |
54 |
DQ26 |
63 |
DQ14 |
72 |
GND |
Notes:
MP0, MP1, MP2, MP3 are N/C on all x32 bit modules
A9 is a N/C on 256k and 512k modules
A10 is a N/C on 256k, 512k, 1M and 4M modules
RAS1/RAS3 are N/C on 256k, 1M and 4M modules
Trapdoor |
SIMM (2 & 8Mb) |
DRD0-DRD15 |
DQ0-DQ15 |
MA0-MA8 |
A0-A8 |
CASL1 |
-CAS0 |
CASU1 |
-CAS1 |
RAS0 |
-RAS0 |
RAS1 |
-RAS1 |
WE |
-WE |
+5V |
Vcc (10, 30, 59) |
GND |
Gnd (1, 39, 72) |
Trapdoor |
SIMM (1 & 4Mb) |
DRD0-DRD15 |
DQ0-DQ15 |
DRD0-DRD15 |
DQ16-DQ31 |
MA0-MA8 |
A0-A8 |
CASL1 |
-CAS0
+ -CAS2 |
CASU1 |
-CAS1
+ -CAS3 |
RAS0 |
-RAS0 |
RAS1 |
-RAS2 |
WE |
-WE |
+5V |
Vcc (10, 30, 59) |
GND |
Gnd (1, 39,72) |
A600
Trapdoor
Pin |
Function |
Pin |
Function |
Pin |
Function |
Pin |
Function |
Pin |
Function |
Pin |
Function |
Pin |
Function |
Pin |
Function |
1 |
VCC |
11 |
DRD6 |
21 |
GND |
31 |
DRA8 |
41 |
RGA8* |
51 |
D2* |
61 |
NET_CS* |
71 |
IOR* |
2 |
VCC |
12 |
DRD7 |
22 |
GND |
32 |
DRA9 |
42 |
RGA7* |
52 |
D3* |
62 |
Sp_CS* |
72 |
IOW* |
3 |
GND |
13 |
DRD8 |
23 |
DRA0 |
33 |
CASU(0)* |
43 |
RGA6* |
53 |
D4* |
63 |
INT2* |
73 |
RTC_CS* |
4 |
GND |
14 |
DRD9 |
24 |
DRA1 |
34 |
CASL(1) |
44 |
RGA5* |
54 |
D5* |
64 |
INT6* |
74 |
Sense* |
5 |
DRD0 |
15 |
DRD10 |
25 |
DRA2 |
35 |
CASL(0)* |
45 |
RGA4* |
55 |
D6* |
65 |
LEFT* |
75 |
GND** |
6 |
DRD1 |
16 |
DRD11 |
26 |
DRA3 |
36 |
CASU(1) |
46 |
RGA3* |
56 |
D7* |
66 |
RIGHT* |
76 |
VCC |
7 |
DRD2 |
17 |
DRD12 |
27 |
DRA4 |
37 |
RAS0 |
47 |
RGA2* |
57 |
A1* |
67 |
14.3 MHz |
77 |
GND |
8 |
DRD3 |
18 |
DRD13 |
28 |
DRA5 |
38 |
RAS1 |
48 |
RGA1* |
58 |
A2* |
68 |
TEST* |
78 |
GND |
9 |
DRD4 |
19 |
DRD14 |
29 |
DRA6 |
39 |
WE |
49 |
D0* |
59 |
A3* |
69 |
CCK* |
79 |
+12V* |
10 |
DRD5 |
20 |
DRD15 |
30 |
DRA7 |
40 |
ROE* |
50 |
D1* |
60 |
A4* |
70 |
RESET* |
80 |
-12V* |
*Pins
not used in this hack.
**Pin
75 is grounded via one 470W resistor (low wattage).
The connector could be made from a PCI slot
“taked” from a PC (finally something good to do with one ;-) ). Count 40 (80)
pins and cut (in the side with all pins, obviously). Or buy new Digikey
(1-145154-2) or Farnell (1144437) PCI slot.
If you want to put the SIMM in a SIMM socket,
scavenge one from the same old-dead pc or buy Digikey (5822134-3-ND) or Farnell
(1101362) angled SIMM socket.
Note: use one 10~47μF capacitor in each +5V wire to
decouple the lines (avoid fluctuations). Common capacitors are not needed, if
the SIMM have them.
When using 4 and 16Mb simms for A600
chipram, you have to connect databus together for 16bit mode: D0 to D16, D1 to
D17, ..., D15 to D31! Or it will not work.
The printed circuit board (for those who
wants to make one), must be dual layer.
My best wishes to people who want to make his/her own board! I just
solder a bit of board to provide support to the memory SIMM and do the rest
with wire. Ugly as hell, but works!
Pin descriptions:
VCC:
+5V
GND:
GND
N/C:
not connected
DRD:
DRAM Data Bus
DRA:
DRAM Address Bus
CAS:
DRAM Column Address Strobe*
RAS:
DRAM Row Address Strobe
WE:
DRAM Write Enable
ROE:
DRAM Output Enable
RGA:
Custom Chip Register Address Bus
Dx:
CPU Data Bus
Ax:
CPU Address Bus
NET_CS:
I/O select (Gayle pin 14)
Spare_CS
(Sp_CS): spare I/O select (Gayle pin
15)
INT2 e
INT6: Interrupt Request
LEFT
& RIGHT: directly connected to Paula audio channels
14,3MHz:
system clock
CCK:
Color Clock (3.58 MHz)
RESET**:
SYSTEM RESET
TEST:
Special Function, probably equivalent to some TP1 pin from A1200.
IOR:
I/O Read RTC
IOW:
I/O Write RTC
RTC_CS:
RTC Chip Select
Sense
???
ATENTION:
only the CAS(1) pins are utilized! The CAS(0) are only used in the INTERNAL
memory of A600.
**
This is the “external” RESET pin from A600. Not tested by me.
Thanks to:
Vitaly Grebennik (author of the original hack)
LordVader/nedoPC (Russian translation help)
Dieter Marno (for the help in schematics)
Nivardo Cavalcante (for the pinouts of Amiga 600)
Ian Stedman (for useful suggestions)
To everybody who have encourage me to keep going with this hack!
Rogério Kauer
January 2008