> C=Y RM=80 LM=2 TM=1 BM=66 J=NTRS-80 Model 4 HD64180 and Memory Modification> C=NMOD4FIG1/TXT - Updated 01/21/87                               Fig 1               All chips are piggybacked and use Vcc & Vss on the host chip.                         |--------------|                 +5 >-----|                                  |   74LS244    |                     |----|----|  See Note 3    D0  >--------|12 Addr 16   8|---------------------|2a0 15   |     Pin 1-A8   D1  >--------|16 Addr 17   4|---------------------|5b0   d 9|---> 256K Rams  D2  >--------|3  Addr 18  17|--->        HDA16 >--|3a1   c12|---> A18A       D3  >--------|18 Addr 19   2|--->        HDA17 >--|6b1   b 4|----------|A17  D4  >--------|5  Addr 20  15|--->        HDA18 >--|13c1  a 7|-------|  |A16  D5  >--------|14 Unused=0  6|-->   BK 64 U14P-8 >-|14c0     |       |  |     D6  >--------|7  W Protect13|-->                  |  74LS157|       |  |     D7  >--------|9  Z80/MMU  11|---------------------|1M 3-U35P|       |  |                  |   1-U41P 1&19|--|             |----|10d1 Mux |       |  |                  |--------------|  |             | |--|11d0     |       |  |           ________   5-U25P        |             | |  |---------|       |  |     U50-10 Port 94 >10|----\       |             | |----------------|   |  |             __        | LS32|8-----|             *---1|----\        |   |  |     U48-4   IN >-----9|----/ OR                  |    | S08 |3------|   |  |                  |--------------|       U14P-11>-|---2|----/  AND       |  |                  |    74LS273   |                |      9-U27P          |  |     D0  >--------|13 Addr 16  12|-< U41P-8       |     |---------|      |  |     D1  >--------|14 Addr 17  15|-< U41P-4       |-----|4a    3a1|------|  |     D2  >--------|17 Addr 18  16|-< U41P-17            |      2a0|---------|     D3  >--------|18 Addr 19  19|-< U41P-2             | 4-U63P  |    ____       D4  >--------|3  Addr 20   2|-< U41P-15      +5 >--|5 LS157 7|--> ICAS       D5  >--------|4  Unused=0  5|-< U41P-6       Gnd >-|6,15   1 |   See Note 2  D6  >--------|7  W Protect 6|-< U41P-13            |-------|-|               D7  >--------|8  Z80/MMU   9|-< U41P-11                    |->Mux See Note 1 U17-8 Reset>-|1         11  |                  ____        |------------|                 |----------|---|                  MREQ        |--------|   |                   2-U37P   |     On all 157's     U38-12 >----|2 D   Q |---|     _______                |     pin 15 is to     Pclk        |6-U53P 4|--< +5   Port 94   5-U25P       |     be grounded   HD64180-64>----|2 Ck   1|--|     U50-10 >--1|----\       |                   Use Z80-6 if   |--------|  |                | LS32|------|                   the 64180 is___   S74      |     U49-4 >---2|----/                           not used.   REF U60-4 >----|      ___         OR                                                               OUT                                                                                                   |----> AD18 U37P-16                                                          |-5|-----\                                        AD19 U37P-19 >-|-----\        | LS32 |6----9|----\                                          | LS32 |3-----4|-----/       | S08 |8--> U35P-14              AD20 U37P-2  >-|-----/        7-U39P     |10|----/      Bank 64K                            7-U39P            OR      | 10-U14P                                             OR                     |     AND                            U55-18 >----1|----\                     |                                    A15          | S86 |3------12|----\     |                                             |--2|----/          | S08 |11:-*--> U27P-2                          U37-6 >--|  8-U12P     |---13|----/          Bank                           FXUPMEM        XOR      |    10-U14P                                          U37-2 MB0 >-4|----\    |       AND              The Only Cutting Needed:                  | LS32|6--|                                                     U37-5 MB1 >-5|----/           | Note 1. MUX - Cut trace from U18-7&13 to                 5-U25P            |            feed through just below U18-8                    OR             |            Connect U63P-1 to Feed through   Note 3. A8 - Remove R44 & the  | Note 2. ICAS - Cut Trace from U18-12 to     Jumper between E11 & E12. Connect a wire |  feed through under R53           from U35P-9 to E12 & also to the RAM     |  Connect U63P-7 to Feed through   side of R44 pad.                         |  under R53                            