18 Nov
2003
18 Nov
'03
1:23 a.m.
Holger wrote:
The HP41 is rather moderate in speed, with a clock of
300kHz and an
instruction cycle length of 56 bits, so it is no problem at all to
write a precise emulator with one or two modern microcontrollers
(you wouldn't just take the lowest level choice like a PIC which is
too inferior for this, but maybe a 16 bit controller like an MSP 430).
Actually the PIC is ideally suited to this, because what you need is
high speed, not 16-bit wide or fancy instructions.
I got the HP-45 microcode running on a PIC-based emulator about eight
years ago. The first-generation HP calculator chipset had a similar
architecture in most regards to the later chipset used in the HP-41C,
but ran at 196 KHz (still with 56 bit times per instruction cycle).
I wasn't trying for cycle accuracy or electrical compatability,
though that wouldn't have been too difficult if it had been my objective.
Eric