pcjs/devices/vt100/rom

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VT100 ROMs

The VT100 used four 2Kb ROMs to store the code used by its 8080 processor. Their combined contents are stored in VT100.json.

As Trammell Hudson's VT100 Page explains:

There are four 8316E ROM chips for the 8080 CPU on the logic board. Since they are custom mask ROMs,
Digital was able to have a different chip-select bit pattern and avoided having separate NOT gates on the inputs.
Note that the schematic appears to be incorrect -- E56 is the low order, and E40 is the high order address bits.

He then describes the memory mapping as follows:

ROM chip    CS1 (20)    A11/CS2 (18)    A12/CS3 (21)    Mapped address
E40         H           H               H               0x1800
E45         H           L               H               0x1000
E52         H           H               L               0x0800
E56         H           L               L               0x0000

The above PCB chip locations correspond to the following DEC ROM dumps:

• E56: 23-061E2.bin
• E52: 23-032E2.bin
• E45: 23-033E2.bin
• E40: 23-034E2.bin

And sure enough, concatenating those DEC ROM four dumps produces a perfect match for Trammell Hudson's VT100.bin.

The VT100 also used one 2Kb character generator ROM, which is stored in 23-018E2.json.