On 06/02/2018 03:33 PM, Antonio Carlini via cctech wrote:
On 02/06/18 15:17, allison via cctech wrote:
It was my understanding from using the 730 that there was
(really limited) microcode
enough to load the WCS as the tu58 was a serial device
and the 730 had to
unpack and stuff the WCS. You need little to do that but
far from even
PDP11 instruction set.
The Microcode was loaded was the "what made it a VAX stuff".
Well something has to load the ucode but whether that's a
fixed part of ucode itself or whether
it's a hardware state machine (or something) that feeds
the loaded ucode into the appropriate
RAM, I don't know. I've never delved that deeply into the
relevant FMP sets.
Actually, the 8085 could load a small bootloader from 8085
ROM to the 730 microcode. That would be the most logical
way to do it, assuming the microcode bootloader was really
The IBM 360/25 had all microcode in the top 16K of main core
memory, and the emulator of your choice could be loaded from
binary punch cards. The microcode bootloader was
hand-loaded through the front panel switches, and occupied
16 16-bit words.