lua-users home
lua-l archive

[Date Prev][Date Next][Thread Prev][Thread Next] [Date Index] [Thread Index]

Really, happy days ...

Did you said 256K? Lucky you ... We started with 32K and then 64K.

My master's degree project was to develop part of a node for REDPUC, an experimental pre-Ethernet packet network.

We've developed it all from scratch: hardware, BIOS, multiprogramming core and OSI protocol up to level 2.

With a huge team of one person (Me) ...

Em 2019-11-02 19:16, Tim Hill escreveu:
On Oct 31, 2019, at 6:58 PM, Fernando Jefferson
<> wrote:
At PUC-Rio we did reverse-engineering of CP/M 80, obtained a source
file, first in assembler and then in "C". And even we´ve developed
a CP/M 86, with the providential help of Roberto Ierusalimschy (my
colleague in the master's degree), who developed a genial
interpreter for the 8085 CPU, running on the Intel 8086. Mapping
registradors from one CPU to another!

Ah good memories. I did a similar thing for a commercial computer
system way back, which allowed us to move to x86 systems but still run
all the 8-bit 8080 software(quite a lot at the time) on the newer
machines. It really wasn’t that difficult as the x86 used a similar
model for flags, so it was really a matter of decoding the 8080
instruction and then mapping it to the equivalent 8086 instruction(s).
As I recall, the emulator run at about the same speed as the real
hardware. The OS mapping was equally simple, as CP/M and CP/M 86
mapped 1:1 for OS calls.

Happy days .. when 256K was a LOT of RAM :)


Fernando Jefferson
CCE-PUC-Rio - Professor
Projeto UpLua - Coordenador
Cel: +5521-99763-2135