TI99: WP and PC

<Except for a significant penalty in register access time, maybe. Could <be worth it if you expected lots of context switches. Access penalty is high as ram in '77 was slow. <Sounds to me like the 1802. Is there any shared history between them? <Were the 1802 designers consciously influenced by the TI design, or was <it derived again from scratch? Not even close. There is no shared history either as noth evolved from the larger systems each made. The registers in the 9900 were very general in use and symetrical in adressing modes. The 1802 the registers were not general. They were mostly for pointers, stacks, and maybe storage. The 1802 had the ability to use any register as the program counter (via sep and interrupts). The TI9900 the PC is one of the few hardware registers. The 1802 is a primary accumulator machine and the 9900 is anything but as all registers are the target for the result. <Hmm, 1802's were used in satellites, right? Do satellite apps need lots <of context switching? They would like that but the 1802 was used as it was available as RAD hard and CMOS (low power!). The latter is more important as 10mW is nothing compared the the ~600mW of the 9900 cpu never minding clock generation (ttl 4 phase clock generator) support. Allison