CHA256B
COPIED VERBATIM FROM THE CHA256 ENTRY, NEEDS TO BE CHECKED
C ROMs
Up to 8 * 32Mbit ROMs (27C322) can be used for a maximum of 256Mbit. 27C800/27C160 can also be used depending on jumper configuration.
The size of largest ROM is selected using a pair of jumpers. The rest should be left unconnected.
| Largest C ROM | Jumper set |
|---|---|
| 1MiB | J5+J6 |
| 2MiB | J7+J8 |
| 4MiB | J9+J10 |
A NEO-273 and a LS74 are used to address C ROM. The LS74 provides the 2 most significant bits. The LS139 enables one of four pairs of C ROMs using 2 address inputs depending on which 2 jumpers are connected.
AES version
| C ROM type | Jumper set |
|---|---|
| <4MiB | J15+J16+J17+J18 |
| 4MiB | J11+J12+J13+J14 |
| M1 ROM size | Jumper set |
|---|---|
| 64KiB | J1+J4 |
| 128KiB | J2+J3 |
| EVEN delay | Jumper set |
|---|---|
| 1 gate | J19 |
| 2 gates | J20 |