Hardware

Ok, here's pic of the HB pcb (with flashroms instead eproms).
Works fine.. so far.



Where's the protection device?
Good question. Looks like whole system hw is one big "protection".
Probably it's the SEI300 chi near 68k (with "TAD" sticker).
It's Toshiba gate array TC25SC gate array.
TC25 features (accordig to 'CMOS ASIC Design Manual' from Toshiba) :
- embedded megacells
- analog megacells
- MPU core (Z80 compatible)

Toshiba cell lib includes:

• 16 x 16 multiplier
• 8-, 16-, 24-, and 32-bit adder/subtractors
• 32-bit, 2-operand full adder
• 32-bit, 3-operand full adder
• 16- and 32-bit barrel shifters
• 8-bit ALU
• 8-bit CLA
• CRT controller
• Direct memory access controller (DMA)
• Programmable communications interface (PCI)
• Programmable interval timer (PIT)
• 8-bit programmable peripheral interface (PPI)
• Programmable interrupt controller (PIC)
• 4-bit microprocessor slice
• Carry lookahead generator
• Microprogram controller
• Graphical memory (256 x 24)

And others. No idea whats used in SEI300.
Of course there's more custom chips on the pcb, so there's possibility that
the protection (or rather - system features (dma, mcu(?), video) is "spreaded"
across them.

Btw. would be nice to read this