A Confidence RAM Test for Apple IIIs is on the Confidence Disk and the Dealer
Diagnostic Disk. With this test, you can locate bad chips on a 12-volt board.
--> NOTE: Before running the Confidence RAM test, remove all peripheral cards
from the Apple III, especially any ProFile interface cards and
Grappler printer cards.
The test results show the bank, address, and test expectations and actual
performance. For example, after the test, say the console displays:
BNK 82, ADR 67AF, EXP 40, GOT 48.
To locate the bad chip, you must translate these results into a map that
corresponds to the 3 banks of 16 chips on the memory board.
1. The bad chip is in bank 2. The bank number comes from the last digit of
the BNK field.
BANK: 0 x x x x x x x x x x x x x x x x
BANK: 1 x x x x x x x x x x x x x x x x
BANK: 2 X X X X X X X X X X X X X X X X
2. The bad chip is in the right side of the bank. The side is determined by
the range that the address, 67AF, the number in the ADR field, falls
into.
ADDRESS RANGE: ADDRESS RANGE:
2000-3FFF 4000-7FFF
8000-9FFF
BANK 0 x x x x x x x x x x x x x x x x
ADDRESS RANGE: ADDRESS RANGE:
0800-0FFF 0000-07FF
1800-1FFF 1000-17FF
C000-C7FF A000-BFFF
D000-D7FF C800-CFFF
E000-FFFF D800-DFFF
BANK 1 x x x x x x x x x x x x x x x x
ADDRESS RANGE: ADDRESS RANGE:
2000-5FFF 6000-9FFF
BANK 2 x x x x x x x x X X X X X X X X
3. The bad chip is in location number B5. The bad chip shows up in the
comparison of the binary representation of the hexidecimal values in the
fields EXP and GOT, which contain the test expectations and performance.
Any difference between the two is a map of where to find the bad chip or
chips.
hexidecimal binary hexidecimal binary hexidecimal binary
0 0000
1 0001 6 0110 B 1011
2 0010 7 0111 C 1100
3 0011 8 1000 D 1101
4 0100 9 1001 E 1110
5 0101 A 1010 F 1111
EXP = 40 (hexadecimal) = 01000000 (binary)
GOT = 48 (hexadecimal) = 01001000 (binary)
EXP = 40 (hexadecimal) = 0 1 0 0 0 0 0 0 (binary)
GOT = 48 (hexadecimal) = 0 1 0 0 1 0 0 0 (binary)
ok ok ok ok ! ok ok ok
ADDRESS RANGE:
6000-9FFF
BANK 2 x x x x x x x x x x x x X x x x
In the chip location number B5, the letter comes from the letter of the
banks of chips on the memory board:
LETTER: D
BANK: 0 x x x x x x x x x x x x x x x x
LETTER: C
BANK: 1 x x x x x x x x x x x x x x x x
LETTER: B
BANK: 2 x x x x x x x x x x x x X x x x
The number comes from the number of the chip on the memory board:
NUMBER: 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2
LETTER: D x x x x x x x x x x x x x x x x (BANK 0)
C x x x x x x x x x x x x x x x x (BANK 1)
B x x x x x x x x x x x x X x x x (BANK 2)
Replace the bad memory chip(s) and run the test again. If the system fails the
memory board test, exchange the memory board itself. If that dosen't help,
exchange the main logic board.