🚀 go-pugleaf

In Message-ID: <15...@bfmny0.BFM.COM>, Tom Neff posted
>YES!  Crusty elders like David seem to have about 5 years on me -- I
>started programming in 1971 -- but the nice thing about colleges is that
>yesterday's technology is usually still around. :-)  We had those damn
>Wangs with the card reader.  KEE_RIST what lousy hardware we used to
>make do with!  That's what the microcomputer revolution REALLY did:
>banish things like the Wang "Computer cluster"
>and the 1130 to the junkyard where, ultimately, they belonged.
 ^^^^^^^^^^^^

Ahem!  I take objection to that!
The 1130 is a fine machine for learning machine architecture.
It had a very thoughtful interrupt structure and a front panel that
let you see that machine's state all over.

I know, there are now emulators that show you more, but they're NOT REAL!
Are you going to believe a software simulator that tells you the
accumulator contains "f001" or the panel lights?

I have pieces of the 1130 all over my workshop,
including the emergency pull switch.

The "mode" switch was the most important debugging tool.
"RUN" ran at full speed.
"INT" caused an interrupt after every instruction
	(level 5 - the lowest priority)
	This allowed you to activate a routine for tracing, etc.

	I don't recall having any debuggers that used this, but
	in this very newsgroup we've heard about lots of later machines
	that did NOT offer single step ability and all the tricks
	needed to get around that shortcoming.
"SI" (Single Instruction) stopped at every instruction
"SMC" (Single Memory Cycle) stopped after every memory cycle
	(opcode fetch, etc).
"SS" (Single Step) stopped at every clock cycle
	(there were usually 8 clock cycles per memory cycle).
	This let me see the operations going across the registers
	one bit at a time.

The manuals gave the flowcharts for EVERY instruction.
Use SS and follow along with the machine!

The Monitor didn't pretend to be an OS.  It just loaded programs from the
disk and let you run.  The runtime libraries overlaid the monitor.
If the program didn't fit into the memory, then just declare some
subroutines LOAD ON CALL and the linker automatically did the overlays
as they were called.  Still not enough room?
Use SOCALS: System Call Load On Call.
The non-interrupt driven code could be loaded on call, but this
degraded performance so it was the second tier of load on call.

Did the PC DOS loader offer this flexibility?  NO!
Somebody at Microsoft didn't learn.

-- 
Jeffrey Jonas
jeffj@synsys.uucp