On Fri, 3 Dec 2004, ben franchuk wrote: Yes, but no 8x300... clearly, www isn't the only source of data, just the most convenient :-) As always, it's a matter of how important it is to me, whether I'll go scare up a manual. I'll probably just 'keep my eyes open' rather than turn it into A Project -- I have enough of those! But I am getting a bit obsessed with subroutine-call mechanisms so I might make the effort.

On Fri, 3 Dec 2004, Peter C. Wallace wrote: Well yes, strictly speaking it doesn't really support subroutines. The mechanism WAS clumsy, and there were a limited number of "returns" available due to the jump table business (basically copies a number from the table to the "PC"). If I could find so much as the instruction set I could re-create it. Well Microchip's PICs are CISC relative to the SMS/Signetics thing. Seven? instructions, 16 special registers. The code I worked on was a real-time video processor, written by a Real Programmer named Cal Hawke or Hawkes (Avco-Everett Research Lab, my one sole defense job). He was a grad student? maybe 3 yrs older than me. There was a CCD camera mounted on a gymbal looking out the side of a Boeing 707 or something. It flew around looking for objects reentering the atmosphere, incandescing. The 8x300 code was meant to (...) generate X, Y data to feed the error loop of the servo driving the gymbal. The code centroided a blob/bright spot and output coords in some local system. Cal had also encoded a debugger! into the code so that you could talk to it with a serial port as it worked. There was 2K of data and over 1K of code, I think, with complex and dangerous (to the programmer's brain) bank-switching using ports. Code was tested by burning $20 bipolar fuse PROMs. It ran at 4MHz, one instruction per clock. THe code was spectacularly intricate, it's hard to explain just how weird it was with all the interleaved user interface and the video code. No stack, no interrupts, just one long thread of code. I could barely hang on. Cal was leaving (as all grad students do) and I took over maintaining it. Back to the point, it used a lot of "subroutines". Like a PIC, the instructions were wider (16?) than the data buss (8 bits). The instructions I remember are: XMT r "transmit" a constant to reg r (same as movlw), also does "jump" ADD r aux + r --> aux XEC ? execute instruction as "one instruction subroutine" not sure arg Well that's about half of them!

On Fri, 3 Dec 2004, Brad Parker wrote: yup. Now I never met him, of course, but he's pretty roundly reviled. I'm reading the Babbage Inst's reprint and even there, it states that though Aiken was a lecturer, that 'he largely seemed unaware of the importance of what was being discussed [fully electronic stored-program...] and delved in deeply to the workings of his relay calculators' (paraphrase from memory) Apparently working in his shop was like slavery. I've not read one account that actually liked the guy. Overbearing empire-builder and Spender of Govt Money. Nice calculators though. (The arch ref is that the relay calc programs were stored on very wide punched tape, external to data storage. They were truly significant machines of great power and complexity (logical error-checking, remote consoles, skip-to-next-queued-up-program-on-error, all sorts of nicities. He simply was an unpleasant person.) TO be honest I don't know much about all the parallel processing stuff; so they were somewhat silly?

Your loss! I bought my first airplane as a result of a TMI stock deal. ----- Original Message ----- From: "Brad Parker" <brad(a)heeltoe.com> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org> Sent: Friday, December 03, 2004 5:31 PM Subject: Re: Signetics 8x300 instruction set