1.Mapper bits 7 and 6 of the data must be 1 for the Mapper write.
2.Printer data-bits are connected to AY I/O port B.
3. Multiport is similar to the Gate-Array in cpc.
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|''bit 7'''||''bit 6'''||Action
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|0||0||Pen index write (note 5)
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5. If bit 3 is set, border is selected. Otherwise bits 3..0 define the pen index.
6. The number is converted by IC D62. When MAPPER is set in EXTPORT, then the numbers effectively define R,G,B with 2 bits per element, but the rom then changes the order of the bits before it gets to the hardware.
When MAPPER is not set, the number is equivalent to the CPC's Gate-Array colour value, but this is looked up in IC D62 and converted into a 2-bit per element R,G,B for the aleste video hardware.
7. bit 0,1 define the mode. The actual resolution is then dependant on bit 1 of EXTPORT.
8. bit 2 is the enable/disable for the lower rom. bit 3 is the enable/disable for the upper rom. bit 4 defines the RUS led. bit 5 defines the CAPS led.
9. The number is looked up in IC and converted into another number which is the 16K page index in the Aleste's internal 64k ROM.
10. bit 2 = enable/disable MAPMOD (changes how colour is decoded and how mapper values are decoded), bit 3 = force video to black, bit 4 = Enable 8253 timer. Any I/O write then accesses 8253 with data comming from 8255 port A. Bit A0/A1 of I/O port defines 8253 register, bit 5 = if 0, then AY is accessed when read/write to 8255 port A, if 1 then real-time clock is accessed with read/write to 8255 port A. When real-time clock is selected, bits 3..0 of PPI port C are used to define real-time clock operation. DS bit 2, AS bit 1, R/W bit 0. So combinations are 2, write address, 4 write data, 5 read data.
10. bit 2 = enable/disable MAPMOD (changes how colour is decoded and how mapper values are decoded), bit 3 = force video to black, bit 4 = Enable 8253 timer. Any I/O write then accesses 8253 with data comming from 8255 port A. Bit A0/A1 of I/O port defines 8253 register, bit 5 = if 0, then AY is accessed when read/write to 8255 port A, if 1 then real-time clock is accessed with read/write to 8255 port A. When real-time clock is selected, bits 3..0 of PPI port C are used to define real-time clock operation. DS bit 2, AS bit 1, R/W bit 0. So combinations are 2, write address, 4 write data, 5 read data.
== Technical specs ==