Professional-DOS Release 2, PROM 82S123A

Contents of the PROM 82S123A (74S188), used as address decoder
with the following assignements (view schematic diagram):

A4 - address line A12 from 6502
A3 - address line A13 from 6502
A2 - address line A14 from 6502
A1 - address line A15 from 6502
A0 - address line A11 from 6502

O8 - Fetch 2MHz mode, enabling line to diode D1
O7 - Select-A[0..3|4..7]->AL, (enabling line to IC4)
O6 - ROM-Banksel, A13 line to IC8 and enabling line to IC9
O5 - ROM-/CE, enabling line to IC8
O4 - RAM-/CS1, enabling line to IC9
O3 - /EN-AL->AH, enabling line to IC7
O2 - /EN-A[4..7]->AH, enabling line to IC5, pin 1
O1 - A11-EXT, address line A11 to 6502 adaptor (external A11)

   Address  ||  stored value
   A[43210] ||     O[87654321]
============||================
 0 | 00000  ||  28 | 00011100
 1 | 00001  ||  29 | 00011101
 2 | 00010  ||  28 | 00011100
 3 | 00011  ||  29 | 00011101
 4 | 00100  ||  53 | 00110101
 5 | 00101  ||  53 | 00110101
 6 | 00110  ||  28 | 00011100
 7 | 00111  ||  29 | 00011101
 8 | 01000  ||  28 | 00011100
 9 | 01001  ||  29 | 00011101
10 | 01010  ||  28 | 00011100
11 | 01011  ||  29 | 00011101
12 | 01100  ||  13 | 00001101
13 | 01101  || 141 | 10001101
14 | 01110  ||  44 | 00101100
15 | 01111  ||  45 | 00101101
16 | 10000  ||  52 | 00110100
17 | 10001  ||  29 | 00011101
18 | 10010  ||  28 | 00011100
19 | 10011  ||  29 | 00011101
20 | 10100  ||  52 | 00110100
21 | 10101  ||  52 | 00110100
22 | 10110  ||  28 | 00011100
23 | 10111  ||  29 | 00011101
24 | 11000  ||  28 | 00011100
25 | 11001  ||  29 | 00011101
26 | 11010  ||  28 | 00011100
27 | 11011  ||  29 | 00011101
28 | 11100  ||  10 | 00001010
29 | 11101  ||  74 | 01001010
30 | 11110  ||  44 | 00101100
31 | 11111  ||  45 | 00101101