6502 in 28-pin packages
These are just a standard 6502 silicon die in a 28-pin package
to save cost and PCB space. They were not very common. If you
need one, it is easier to get hold of an ordinary 6502 and wire
up an adapter board.
6504 / 6507 CPU
These chips can only access 8K of memory.
Pinout
| !res |
--> |
1 |
--6507-- |
28 |
--> |
clk2 |
| gnd |
-- |
2 |
27 |
<-- |
clk0 |
| rdy |
--> |
3 |
26 |
--> |
r/!w |
| vcc |
-- |
4 |
25 |
<-> |
d0 |
| a0 |
<-- |
5 |
24 |
<-> |
d1 |
| a1 |
<-- |
6 |
23 |
<-> |
d2 |
| a2 |
<-- |
7 |
22 |
<-> |
d3 |
| a3 |
<-- |
8 |
21 |
<-> |
d4 |
| a4 |
<-- |
9 |
20 |
<-> |
d5 |
| a5 |
<-- |
10 |
19 |
<-> |
d6 |
| a6 |
<-- |
11 |
18 |
<-> |
d7 |
| a7 |
<-- |
12 |
17 |
--> |
a12 |
| a8 |
<-- |
13 |
16 |
--> |
a11 |
| a9 |
<-- |
14 |
15 |
--> |
a10 |
|
Variants:
|
The 6507 was used in the Atari 2600 video game controller and
Atari 1050 disk drive.
The 6504 was used in some of old Commodore printers.
The !irq signal is arguably more useful than rdy.
6503 / 6505 / 6506 CPU
More pinout variations. An extra control signal is available,
the address lines shuffled one pin along, and A12 has been
removed. These chips can only access 4K of memory.
Pinout
| !res |
--> |
1 |
--6503-- |
28 |
--> |
clk2 |
| gnd |
--- |
2 |
27 |
<-- |
clk0 |
| !irq |
--- |
3 |
26 |
--> |
r/!w |
| !nmi |
--> |
4 |
25 |
<-> |
d0 |
| vcc |
--- |
5 |
24 |
<-> |
d1 |
| a0 |
<-- |
6 |
23 |
<-> |
d2 |
| a1 |
<-- |
7 |
22 |
<-> |
d3 |
| a2 |
<-- |
8 |
21 |
<-> |
d4 |
| a3 |
<-- |
9 |
20 |
<-> |
d5 |
| a4 |
<-- |
10 |
19 |
<-> |
d6 |
| a5 |
<-- |
11 |
18 |
<-> |
d7 |
| a6 |
<-- |
12 |
17 |
--> |
a11 |
| a7 |
<-- |
13 |
16 |
--> |
a10 |
| a8 |
<-- |
14 |
15 |
--> |
a9 |
|
Variants:
| Pin |
6503 |
6505 |
6506 |
| 3 |
!irq |
rdy |
clk1 |
| 4 |
!nmi |
!irq |
!irq |
|
Of these chips, the 6503 has the most useful signals.