On 18.08.24 07:04, Steve Litt wrote:

> Hendrik Boom said on Sat, 17 Aug 2024 09:32:30 -0400

>

> >If my memory is still good, the first certified ADA compiler was

> >written by a friend ot mine, Robert Dewar.

>

> It's a small world, Hendrik. At Illinois Institute of Technology in 1970

> I had to drop Dr. Dewar's assembler class because I couldn't understand

> indirect addressing, double indirect addressing, or stacks. Keep in

> mind I was only 20 and was smoking weed every other day and drinking

> the other days, and I figured I'd get shot dead in a rice paddy in

> Vietnam so I didn't give a flying flamingo anyway.

...

It'll be the flamingo, I figure. It's taking a keen interest which gives

learning wings. (Mind you, haven't tried weed, so have much to learn

there.) Here in Australia, we had a conscription exemption for uni students, AFAIR, so were spared from "Going All The Way With LBJ."

In 1973, before even the Intel 8080 appeared in Australia, as a second

year student, I programmed an HP2100A 16 bit minicomputer in assembler.

(It was a boxful of TTL chips and ferrite core memory boasting a 980 nS

cycle time, write-back being needed after the destructive read.) It

quickly taught indirect addressing, as there was no subroutine return

instruction, only an indirect jump. A subroutine call saved the return

address in the location before the subroutine entry point, allowing

return via IJMP (Call_Address - 1). That was elegant simplicity - so

long as reentrancy was not needed.

The HP2100A had a display register, made of illuminated pushbuttons,

a bit toggling each time its button was pushed. It took a long time for

me to accept hexadecimal notation after the ease of binary/octal. Even

half a century later, 0b11111111 is 0377 before it is 0xFF in my mind.

If you overwrote the (paper tape reading) bootloader in the top 64 words

of memory, you had to re-input the thing via the display register, LOAD,

and ADDR_INC buttons. We dreamt of one day possibly owning an ASR33

teletype and a Pertec tape drive. (I have one of the latter - will have

to find a home for it before my program terminates.)

Erik