trunk/src/emu/cpu/tms7000/tms7000.c
| r31431 | r31432 | |
|---|
| 25 | 25 | * - TMS70x1/2 serial port and timer 3 |
| 26 | 26 | * - TMS70C46 DOCK-BUS comms with external pins |
| 27 | 27 | * - TMS70C46 external memory mode is via "E" bus instead of configuring IOCNT0 |
| 28 | | * - TMS70C46 clock divider (don't know which part of the memorymap is slow) |
| 28 | * - TMS70C46 clock divider |
| 29 | 29 | * - TMS70C46 INT3 on keypress |
| 30 | 30 | * - when they're needed, add TMS70Cx2, TMS7742, TMS77C82, SE70xxx |
| 31 | 31 | * |
| r31431 | r31432 | |
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| 924 | 924 | // d5: enable external databus |
| 925 | 925 | if (~m_control & data & 0x20) |
| 926 | 926 | m_io->write_byte(TMS7000_PORTE, 0xff); // go into high impedance |
| 927 | | |
| 928 | | // d4: enable clock divider when accessing slow memory |
| 929 | | // d0-d3: clock divider |
| 927 | |
| 928 | // d4: enable clock divider when accessing slow memory (not emulated) |
| 929 | // known fast memory areas: internal ROM/RAM, system RAM |
| 930 | // known slow memory areas: system ROM, cartridge ROM/RAM |
| 931 | |
| 932 | // d0-d3(all bits?): clock divider when d4 is set and addressbus is in slow memory area |
| 933 | // needs to be measured, i just know that $30 is full speed, and $38 is about 4 times slower |
| 930 | 934 | m_control = data; |
| 931 | 935 | } |
| 932 | 936 | |
| r31431 | r31432 | |
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| 936 | 940 | |
| 937 | 941 | READ8_MEMBER(tms70c46_device::dockbus_status_r) |
| 938 | 942 | { |
| 939 | | // d0: slave HSK low |
| 940 | | // d1: slave BAV low |
| 943 | // d0: slave _HSK |
| 944 | // d1: slave _BAV |
| 945 | // d2: unused? |
| 941 | 946 | // d3: IRQ active |
| 942 | 947 | return 0; |
| 943 | 948 | } |
| 944 | 949 | |
| 945 | 950 | WRITE8_MEMBER(tms70c46_device::dockbus_status_w) |
| 946 | 951 | { |
| 947 | | // d0: master HSK low (setting it low(1) also clears IRQ) |
| 948 | | // d1: master BAV low |
| 952 | // d0: master _HSK (setting it low(write 1) also clears IRQ) |
| 953 | // d1: master _BAV |
| 954 | // other bits: unused? |
| 949 | 955 | } |
| 950 | 956 | |
| 951 | 957 | READ8_MEMBER(tms70c46_device::dockbus_data_r) |